o
OJ
Q:
Q.
a I B R.AR.Y
OF THE
UN I VERSITY
Of ILLI NOI5
590-5
FI
Return this book on or before the
Latest Date stamped below.
Theft, mutilation, and underlining of books
arc reasons for disciplinary action and may
result in dismissal from the University.
University of Illinois Library
MOV 1 1 19f7
L161 O-1096
EVOLUTION OF
NEOTROPICAL CRICETINE RODENTS
(MURIDAE)
WITH SPECIAL REFERENCE TO THE
PHYLLOTINE GROUP
PHILIP HERSHKOVITZ
FIELDIANA: ZOOLOGY
VOLUME 46
Published by
CHICAGO NATURAL HISTORY M! S
DECEMBER 20, W&2
CORRIGENDA
FIBLDIANA: ZOOLOGY
VOLUME 46
Page 84, footnote 1: Add to subgenera of Oryzomys, the following, Macruroryzo-
mys, Microneclomys^
Page 97, caption for figure 18B, third line: Read confluence for "coalescence."
Caption for figure 18C, third line: Read confluent for "coalesced."
Page 117, line 16 from bottom: Read ectolophid for "ectoloph."
Page 153, line 13 from bottom: Read provenance for "precedence."
Page 346, line 12 from bottom: Read 14 for "12."
Line 3 from bottom: Read 13 for "12."
Page 347, line 7 from top: Read 11 for "10."
Page 357, in column under "tail pilosity:" Insert X for Urco, and read 14 for "13."
Page 403, on map: Read BRAZIL for "BOLIVIA."
ai 21, 22, InUruhaag* vor4 ltttrgr*d (Ut>
with ord itrtyffl (liM 22).
139, fi* 36, pq^ttilar length is from honwtUun as
1 1 slat >I Ion th nho-il-t ho fr-t '
or front of iuci ,or ,.
FIELDIANA: ZOOLOGY
A Continuation of the
ZOOLOGICAL SERIES
of
FIELD MUSEUM OF NATURAL HISTORY
VOLUME 46
CHICAGO NATURAL HISTORY MUSEUM
CHICAGO, U.S.A.
1962
EVOLUTION OF
NEOTROPICAL CRICETINE RODENTS (MURIDAE)
WITH SPECIAL REFERENCE TO THE
PHYLLOTINE CROUP
3
:
C8
S ca
Ml
3
Be
**p2
2 *^ ^a
C ^ ^5j
3 o ^e
OH W CL,
QP..-2 ft
3 o.
6
-
3 01
03 *
EVOLUTION OF
NEOTROPICAL CRICETINE RODENTS
(MURIDAE)
WITH SPECIAL REFERENCE TO THE
PHYLLOTINE GROUP
PHILIP HERSHKOVITZ
Curator, Division of Mammals
FIELDIANA: ZOOLOGY
VOLUME 46
Published by
CHICAGO NATURAL HISTORY MUSEUM
DECEMBER 20, 1962
Preparation of the manuscript was aided by a grant (G-10753) from the
National Science Foundation.
Library of Congress Catalog Card Number: 62-22372
PRINTED IN THE UNITED STATES OF AMERICA
BY CHICAGO NATURAL HISTORY MUSEUM PRESS
CONTENTS
PAGE
LIST OF ILLUSTRATIONS . 9
PRELIMINARY REMARKS
Introduction 13
Material 15
Acknowledgments and Abbreviations 15
Measurements 16
GENERAL DISCUSSION
Origin, Evolution and Dispersal 16
Classification and Interrelationship 19
Adaptive Radiation '25
Juvenal Characters and Development 27
Reproduction 28
Pocket Populations 28
Sympatry and Allopatry 31
Crop Variation 36
Niche Variation 38
Sociability 41
Ratadas and Plant Fruiting Cycles 42
Hibernation 46
Enemies 46
Ectoparasites 47
SOME SPECIAL EXTERNAL AND CRANIAL CHARACTERS
Feet 51
Tail 53
Bony Palate 54
Supraorbital Region 57
Baculum 58
DENTAL CHARACTERS AND EVOLUTION
Enamel Folds in Rodent Molar Evolution 69
Procingulum and Postcingulum 74
The Mesoloph in the Pentalophodont and Tetralophodont Patterns ... 76
The "Pseudomesoloph" and the Dental Pattern in Cricetine Systematics 80
Dynamics of Rodent Molar Evolution 82
Plication 83
Planation 86
Hypsodonty
Lamination 92
Involution 93
Triangulation 95
Fusion . 97
4 CONTENTS
PAGE
Cylindrification 98
Differential Evolutionary Rates in Upper and Lower Molars 99
Third Molar 100
Molar Roots 101
Upper Incisor 101
Lower Incisor 107
Incisor Indices 107
SYSTEMATIC REVISION OF PHYLLOTINES
Characters of the Phyllotine Group of Cricetine Rodents 116
Key to Genera and Species 118
Calomys Section
Genus Calomys Waterhouse 123
Diagnostic Characters and Key to the Species of Calomys 137
Calomys sorellus Thomas 137
Calomys laucha Olfers 142
Calomys laucha laueha Olfers 149
Calomys laucha lener Winge 157
Calomys lepidus Thomas 160
Calomys lepidus lepidus Thomas 162
Calomys lepidus ducillus Thomas 163
Calomys lepidus argiirus Thomas 164
Calomys lepidus carillus Thomas 164
Calomys callosus Rengger 165
Calomys callosus callosus Rengger 171
Calomys callosus expulsus Lund 174
Genus Eligmodontia F. Cuvier 175
Eligmodontia typus F. Cuvier 183
Eligmodontia typus typus F. Cuvier 184
Eligmodontia typus puerulus Philippi 186
Genus Zygodontomys J. A. Allen 196
Zygodontomys brevicauda cherriei J. A. Allen 203
Zygodontomys brevicauda ventriosus Goldman 204
Zygodontomys brevicauda seorsus Bangs 204
Zygodontomys brevicauda sanctaemartae J. A. Allen 204
Zygodontomys brevicauda brunneus Thomas 204
Zygodontomys brevicauda punctulatus Thomas 204
Zygodontomys brevicauda stellae Thomas 205
Zygodontomys bretncauda thomasi J. A. Allen 205
Zygodontomys brevicauda brevicauda J. A. Allen and Chapman .... 205
Zygodontomys brevicauda microtinus Thomas 205
Zygodontomys lasiurus fuscinus Thomas 205
Zygodontomys lasiurus pixuna Moojen 206
Zygodontomys lasiurus lasiurus Lund 206
Zygodontomys lasiurus brachyurus Wagner 206
Zygodontomys [tlasiurus] lenguarum Thomas 206
Zygodontomys [tlasiurus] tapirapoanus J. A. Allen 207
Phyllotis Section
Genus Pseudoryzomys Hershkovitz 208
Pseudoryzomys wavrini Thomas 215
CONTENTS 5
PACK
Genus Phyllotis Waterhouse 1217
Phyllotis danrini Complex 234
Phyllotis haggardi Thomas 256
Phyllotis andittm Thomas 260
Phyllotis danrini Waterhouse 269
Phyllotis danrini posticalis Thomas 282
Phyllotis danrini magister Thomas 288
Phyllotis danrini definitus Osgood 296
Phyllotis danrini limatus Thomas 299
Phyllotis danrini ntpestris Gervais 302
Phyllotis danrini danrini Waterhouse 320
Phyllotis danrini fulrescens Osgood 325
Phyllotis danrini xanthopygus Waterhouse 327
Phyllotis danrini caprinus Pearson 330
Phyllotis danrini wolffsohni Thomas 339
Phyllofis osilae J. A. Allen 344
Phyllotis osilae osilae J. A. Allen 380
Phyllotis osilae phaeus Osgood 384
Phyllotis osilae tucumanus Thomas 388
Phyllotis osilae nogalaris Thomas 390
Phyllotis micropus Waterhouse 391
Phyllotis pictus Thomas 404
Phyllotis boliviensis Waterhouse 410
Phyllotis boliviensis boliriensis Waterhouse 416
Phyllotis boliviensis flavidior Thomas 419
Phyllotis sublimis Thomas 419
Phyllotis sublimis sublimis Thomas 427
Phyllotis sublimis leucurus Thomas 428
Phyllotis gerbillus Thomas 430
Phyllotis amicus Thomas 438
Phyllotis griseoflarus Waterhouse 441
Phyllotis griseoflavus griseoflavus Waterhouse 451
Phyllotis griseoflarus domorum Thomas 458
Phyllotis edithae Thomas 461
Phyllotis hypogaeus Cabrera 462
Genus Galenomys Thomas 464
Galenomys garleppi Thomas 468
Genus Andinomys Thomas 473
Andinomys edax edax Thomas 481
Andinomys edax lineicaudatus Yepes 482
Genus Chinchillula Thomas 485
Chinchillula sahamae Thomas 490
Genus Euneomys Coues 493
Euneomys chinchilloides chinchilloides Waterhouse 498
Euneomys chinchilloides petersoni J. A. Allen 499
Euneomys noei Mann 499
Euneomys mordax Thomas 500
Euneomys catenatus Ameghino 500
?Euneomys fossor Thomas 500
6 CONTENTS
PAGE
LITERATURE CITED 503
INDEX . .511
TABLES OF MEASUREMENTS AND COMPARISONS
1. Comparative size of bacula in the Phyllotis ssp 65-68
2. Calomys sorellus Thomas 189
3. Calomys laucha laucha Olfers 190
4. Calomys lepidus Thomas 191
5. Calomys callosus callosus Rengger 192
6. Calomys callosus expulsus Lund 193
7. Eligmodontia typus typus F. Cuvier 194
8. Eligmodontia typus puerulus Philippi 195
9. Zygodontomys lasi ur us Lund and Z. bretricaudaJ. A. Allen and Chapman . 207
10. Pseudoryzomys wavrini Thomas 215
11. Phyllotis haggardi Thomas and P. fuscus Anthony 260
12. Phyllotis haggardi Thomas 261
13. Phyllotis andium Thomas and P. darwini posticalis Thomas from Casa-
palca, Lima, Peru 264
14. Phyllotis andium Thomas 267, 268
15. Phyllotis darwini Waterhouse, breeding data 278-281
16. Phyllotis darwini posticalis Thomas 286, 287
17. Phyllotis darwini magister Thomas and sympatric series of P. d. rupestris
Gervais 291
18. Phyllotis darwini magister Thomas and P. d. rupestris Gervais, altitudinal
distribution 294
19. Phyllotis darwini magister Thomas 295
20. Phyllotis darwini definitus Osgood 297
21. Phyllotis darwini limatus Thomas 301
22. Phyllotis darwini rupestris Gervais from successively higher altitudes . . 307
23. Phyllotis darwini rupestris Gervais 312-317
24. Phyllotis darwini darwini Waterhouse 324
25. Phyllotis darwini fulvescens Osgood 326
26. Phyllotis darwini xanthopygus Waterhouse 328
27. Phyllotis darurini caprinus Pearson 338
28. Phyllotis darwini wolffsohni Thomas 342
29. Ph yllotis osilae J. A. Allen, breeding data 356
30. Comparisons of sympatric series of Phyllotis osilae J. A. Allen and P. dar-
wini Waterhouse 357
31. Comparison of Phyllotis osilae osilae J. A. Allen from Arapa, Puno, Peru,
with sympatric P. darwini rupestris Gervais 359
TABLES OF MEASUREMENTS AND COMPARISONS 7
PAGE
32. Comparison of Phyllotis osilae osilae J. A. Allen from Asillo, Puno, Peru,
with sympatric P. d. rupestris Gervais 360
33. Comparison of Phyllotis osilae osilae J. A. Allen from Chucuito, Puno,
Peru, with sympatric P. darwini rupestris Gervais 361
34. Comparison of Phyllotis osilae osilae J. A. Allen from Huacull-mi, Pun:>,
Peru, with sympatric P. darwini rupestris Gervais 362
35. Comparison of Phyllotis osilae osilae J. A. Allen from Juli, Puno, Peru,
with sympatric P. darwini rupestris Gervais 363
36. Comparison of Phyllotis osilae osilae J. A. Allen from Occomani, Puno,
Peru, with sympatric P. darwini rupestris Gervais 364
37. Comparison of Phyllotis osilae osilae J. A. Allen from Pairumani, Puno,
Peru, 13,500 ft., with sympatric P. darwini rupestris Gervais .... 365
38. Comparison of Phyllotis osilae osilae J. A. Allen from Pairumani, Puno,
Peru, 13,000 ft., with sympatric P. darwini rupestris Gervais . . 366, 367
39. Comparison of Phijllotis osilae osilae J. A. Allen from Pomata, Puno, Peru,
with sympatric P. darwini rupestris Gervais 368
40. Comparison of Phyllolis osilae osilae J. A. Allen from Puno, Puno, Peru,
5 km. W., with sympatric P. darwini rupestris Gervais 369
41. Comparison of Phyllotis osilae osilae J. A. Allen from Puno, Puno, Peru,
15 km. W., with sympatric P. darwini rupestris Gervais 370
42. Comparison of Phyllotis osilae osilae J. A. Allen from Umayo, Puno, Peru,
with sympatric P. darwini rupestris Gervais 371
43. Comparison of Phyllotis osilae osilae J. A. Allen from Yunguyo, Puno,
Peru, with sympatric P. darwini rupestris Gervais 372
44. Comparison of Phijllotis osilae osilae J. A. Allen from Huaracondo, Cusco,
Peru, with sympatric P. darwini poslicalis Thomas 373
45. Comparison of Phyllotis osilae osilae J. A. Allen from Ollantaytambo,
Cusco, Peru, with sympatric P. darwini posticalis Thomas 374
46. Comparison of Phyllotis osilae osilae J. A. Allen from Hacienda Urco,
Cusco, Peru, with sympatric P. darwini posticalis Thomas .... 375
47. Comparison of Phyllotis osilae phaeus Osgood from Limbani, Puno, Peru,
13,000 ft., with sympatric P. darwini posticalis Thomas 376
48. Comparison of Phyllotis osilae phaeus Osgood from Limbani, Puno, Peru,
11,000 11,500 ft., with P. darwini posticalis Thomas from Limbani,
15,000 ft 377,378
49. Comparison of Phyllotis osilae osilae J. A. Allen from Choro, Cocha-
bamba, Bolivia, with P. darwini posticalis Thomas from Palmira,
Apurimac, Peru 379
50. Phyllotis osilae osilae J. A. Allen 382, 383
51. Phyllotis osilae phaeus Osgood 387
52. Phyllotis osilae tucumanus Thomas 389
53. Phyllotis micropus Waterhouse 400
54. Phyliotis pictus Thomas .409
55. Phyllotis bolirienxis bolitriensis Waterhouse 418
56. Phyllotis boliviensis flavidior Thomas 418
57. Phyllotis sublimis sublimix Thomas and P. s. leucurux Thomas .... 429
58. Phyllotis gerbillus Thomas . . 433
8 TABLES OF MEASUREMENTS AND COMPARISONS
PAGE
59. Phyllotis amicus Thomas 440
60. Phyllotis griseoflavus Waterhouse, sex ratios and reproduction 450
61. Phyllotis griseoflavus griseoflavus Waterhouse 456, 457
62. Phyllotis griseoflavus domorum Thomas 460
63. Andinomys edax edax Thomas 483
64. Andinomys edax lineicaudatus Yepes 483
65. Chinchillula sahamae Thomas 491
66. Nominal forms of Euneomys 502
LIST OF ILLUSTRATIONS
Habitats of phyllotines in Peru Frontispiece
PACK
1. Map showing distribution of phyllotine rodents in South and Central
America 14
2. Chart showing interrelationship of phyllotines and other American crice-
tines 22
3. Hind feet of phyllotine rodents 52
4. Hard palates in Muridae 55
5. Glandes pene and bacula of cricetines; simple and complex types ... 59
6. Bacula of phyllotines 60
7. Bacula of Phyllotis darwini complex 63
8. Bacula of Phyllotis andium 64
9. Enamel pattern of the molars of Muridae 71
10. Evolution of the occlusal surface of a generalized cricetine molar . 77
11. Molars of Aporodon tenuirostris and Reithrodontomys fulvescens .... 79
12. Lower first molar of Peromyscus truei gilberti 81
13. Upper second molar of the Eocene Theridomys 85
14. Molar planation 87
15. Hypsodonty in rodents 91
16. 17. Lamination and involution in rodent molars 94, 96
18. Fusion and cylindrification in rodent molars 97
19. Forms of incisors in phyllotines 103
20. Types of incisors in rodents 105
21. Incisive and molar planes 108
22. Skull, showing cranial measurements used in text 109
23. Murid skull, dorsal aspect Ill
24. Murid skull, ventral aspect 112
25. Murid skull, lateral aspect 113
26. Murid mandible . . 115
27. Map showing distribution of the genera of the Calomys section in South
America and Panama 122
28. Map showing distribution of the species of Calomys 125
29. Skulls of Calomys lepidus lepidus, C. laucha laucha, C. sorellus, and C. cal-
losus callosus 131
30. Skulls and mandibles of Calomys lepidus lepidus, C. laucha, C. sorellus
and C. callosus callosus 132
31. Skulls of Baiomys taylori and Calomys laucha 133
10 LIST OF ILLUSTRATIONS
PAGE
32. Palate of Baiomys taylori, Calomys laucha and C. sorellus 134
33. Molars of Calomys sorellus, C. laucha, C. lepidus and Baiomys taylori . . 135
34. Skulls of Zygodontomys brericauda, Calomys callosus and Phyllotis griseo-
flavus 136
35. Map showing distribution of Calomys sorellus 139
36. Skull of Calomys sorellus 141
37. Map showing distribution of the subspecies of Calomys laucha .... 145
38. Head and feet of Calomys laucha 146
39. Map showing distribution of the subspecies of Calomys lepidus . . . .159
40. Skulls of Calomys lepidus 161
41. Map showing distribution of the subspecies of Calomys callosus .... 167
42. Skulls of Calomys callosus callosus 168
43. Palate and molars of Calomys callosus 169
44. Molars of Calomys callosus, Zygodontomys bretricauda and Phyllotis griseo-
flarus 170
45. Map showing distribution of the subspecies of Eligmodontia typus . . . 177
46. Skulls of Eligmodontia typus 178
47. Palate, skull and mandible of Eligmodontia typus 179
48. Molars of Eligmodontia typus 180
49. Stages of molar planation shown in Zygodontomys, Eligmodontia and
Phyllotis amicus 181
50. Map showing type localities of the nominal subspecies of Zygodontomys
brericauda and Z. lasiurus 197
51. Skull and mandibles of Zygodontomys brevicauda 200
52. Map showing distribution of the genera of the Phyllotis section .... 209
53. Plantar surface of right hind foot of Pseudoryzomys wavrini and Oryzomys
palustris 210
54. Skulls of Pseudoryzomys waerini, Calomys callosus and Oryzomys palustris 212
55. Skulls and mandibles of Pseudoryzomys wavrini and Oryzomys palustris . 213
56. Molars of Pseudoryzomys warrini, Calomys callosus and Oryzomys palus-
tris 214
57. Map showing distribution of the species of Phyllotis 218
58. Skulls of Phyllotis griseoflarus, P. pictus, P. darmni, P. micropus, P. sub-
limis and P. amicus 224
59. Skulls of Phyllotis griseoflarus, P. darmni, P. micropus, P. sublimis,
P. pictus and P. boliriensis 225
60. Mandibles of Phyllotis griseoflavus, P. darmni, P. micropus, P. sublimis,
P. pictus, P. boliriensis and Mystromys albicaudatus 226
61. Skulls of Phyllotis darmni, Galenomys garleppi, Andinomys edax, Chin-
chillula sahamae and Euneomys chinchilloides 227
62. Skulls of Phyllotis darmni, Galenomys garleppi, Chinchillula sahamae and
Euneomys chinchilloides 228
63. Mandibles of Phyllotis darmni, Galenomys garleppi, Andinomys edax,
Chinchillula sahamae and Euneomys chinchilloides 229
64. Skulls of Mystromys albicaudatus and Phyllotis darwini 230
LIST OF ILLUSTRATIONS 11
PAGE
65. Skulls of Mystromys albicaudatus and Phyllotis darwini 231
66. Palate and molars of Zygodontomys brevicattda, Mystromys albicaudatus
and Phyllotis darwini 231
67. Molars of Mystromys albicaudatits, Phyllotis griseoftavus, I', darwini,
P. micropits, P. pictus, P. sublimis and P. amicus 232
68. Molars of Phiillotis darwini and P. micropus 233
69. Molars of Phyllotis darunni, Galenomys garleppi, Andinomys edajc, Chin-
chillula sahanuie and Euneomys chinchilloides 233
70. Map showing distribution of the subspecies of Phyllotis darwini . . . 235
71. Map showing distribution of Phyllotis haggardi and P. andium in Ecua-
dor 239
72. Map showing distribution of Phyllotis andium, P. haggardi and the
subspecies of Phyllotis darunni in Peru 240
73. Map showing distribution of the subspecies of Phyllotis darwini in south-
ern Peru 243
74 Map showing distribution of the subspecies of Phyllotis darwini and
P. osilae in southern Peru, Bolivia, Argentina and Chile 245
75. Map showing distribution of the subspecies of Phyllotis danvini in Ar-
gentina and Chile 249
76. Map showing contact between Phyllotis osilae and P. darwini posticalis
and probable origin of P. osilae from ancestral form of P. darwini posti-
calis 252
77. Map showing distribution of the subspecies of Phyllotis osilae and P. dar-
wini in southern Peru, Bolivia, northern Argentina and Chile. . . . 253
78. 79. Skulls of Phyllotis haggardi and P. darwini rupestris 272, 273
80. Abnormal skulls of Phyllotis darwini 274
81. Left molars of Phyllotis darwini 275
82. Age-size variation in Phyllotis darwini limatiis 298
83. 84. Skulls of Phyllotis darwini caprinus and P. d. wolffsohni . . . 332, 333
85. Upper molars of Phyllotis darwini caprinus and P. d. wolffsohni . . . . 334
86. Comparisons of Phyllotis osilae and P. darwini 349
87. 88. Skulls of Phyllotis darwini and P. osilae 354, 355
89. Map showing distribution of Phyllotis micropus 393
90. Skulls of Phyllotis micropus 396
91. Molars of Phyllotis micropus 397
92. Map showing distribution of the subspecies of Phyllotis pictus . . 403
93. Skulls of Phyllotis pictus 406
94. Map showing distribution of the subspecies of Phyllotis bolipienxi* . 411
95. Skulls of Phyllotis boliviensis
96. Molars of Phyllotis boliviensis .414
97. Map showing distribution of subspecies of Phyllotis sublimis . . 420
98. Skull of Phyllotis sublimis 423
99. Molars of Phyllotis sublimis 424
100. Map showing distribution of Phyllotis gerbillus and P. amicus
101. Skulls and molars of Phyllotis gerbillus and P. amicus 436
12 LIST OF ILLUSTRATIONS
PAGE
102. Skulls and molars of Phyllotis amicus and P. gerbillus 437
103. Map showing distribution of the subspecies of Phyllotis griseoflavus . . 443
104. 105. Skulls of Phyllotis griseoflavus 444, 445
106. Molars of Phyllotis griseoflavus 447
107. Molars of Phyllotis hypogaeus 463
108. Map showing type localities of Galenomys garleppi, Phyllotis hypogaeus,
and P. edithae 465
109. 110. Skulls of Galenomys garleppi and Phyllotis sublimis 467, 469
111. Molars of Galenomys garleppi and Phyllotis sublimis 470
112. Map showing distribution of the subspecies of Andinomys edax . . . 472
113. Skulls of A ndinomys edax 475
114. Molars of Phyllotis griseoflavus and Andinomys edax 476
115. 116. Molars of Neotoma (Hodomys) alleni, Neotoma (Teonoma) cinerea,
Neotoma (Neotoma) mexicana, Andinomys edax and Phyllotis griseo-
flavus 478, 479
117. Map showing distribution of Chinchillula sahamae 484
118, 119. Skulls of Chinchillula sahamae 487
120. Molars of Chinchillula sahamae 488
121. Map showing type localities of the subspecies of Euneomys chinchilloides 492
122. Skulls of Euneomys chinchilloides 495
123. Molars of Euneomys chinchilloides 497
Evolution of Cricetine Rodents
INTRODUCTION '
Phyllotines are grazing, or pastoral, cricetines confined to the
Neotropical region. They may be as small as house mice or as large
as Norway rats. Their ancestors, along with other grazing and
aquatic mice, were among the first cricetines to invade South Amer-
ica over the Panamanian land bridge. Today, nearly every impor-
tant grazing and grazing-browsing range of the Neotropical region
from Costa Rica south to the Straits of Magellan, from sea level to
more than 5000 meters above, or to the highest points capable of
sustaining mammalian life, is occupied by one or more species of
1 This paper was submitted for publication in 1956 and was in galley proof when
a published revision of the genus Phyllolis by Oliver P. Pearson came to hand in
December, 1958. Pearson's work includes many advances over our erstwhile
knowledge of the systematics and ecology of the species and subspecies included
by me in the Phyllotis darwini complex. Many of Pearson's contributions are
based on a considerable amount of material studied and collected in the field by
the author himself. A part of this collection, totaling approximately 400 specimens
including the bacula of 113, has since been made available to me by Dr. Seth B.
Benson and Dr. Oliver P. Pearson of the Museum of Vertebrate Zoology, Uni-
versity of California. I am particularly grateful to them for their kindness. My
study of this material has resulted in an interpretation of the inter-relationship of
the members of the Phyllotis darwini complex which differs in some ways from
Pearson's own.
A number of other important contributions to our knowledge of cricetine
morphology and phylogeny also have appeared since 1956. Those pertinent to
the present study have been taken into account either in the text or in footnotes.
A series of short papers by Vorontsov (1957, 1959a, b, 1960a, b) on the anatomy
of soft parts, zoogeography, adaptive radiation and systematics is of particular
interest. Unfortunately, Vorontsov's documentation in support of his generaliza-
tions and broad conclusions is sparse. The number of specimens dissected is not
given and the variety of New World cricetines examined is small. Strangely,
Vorontsov gives no indication that he is familiar with the bulk of the recent litera-
ture on New World cricetines published in North and South America. Finally,
on March 1, 1962, I received the second part of Dr. Angel Cabrera's Catalog dc
los mamiferos de America del Sur. His classification of the species of I'hyllotix is
that of Pearson. His treatment of the genera Calomyx and Eligmodontia may re-
flect the content of some of the correspondence between him and me and, possibly,
my determinations of a number of cricetines in the collection of the Buenos Aires
museum. Other revisions made by Cabrera were not anticipated and correspond-
ing changes in the text could not always be made at this date except by way of
footnotes.
13
14
FIELDIANA: ZOOLOGY, VOLUME 46
90
70
50
20
20
40
i i
PHYLLOTIS SECTION
20
20
40
90
70
50
30
FIG. 1.- Map of South and Central America showing distribution of the
phyllotine rodents.
phyllotines (fig. 1). Rapid and pervasive dispersal of the group was
promoted by the availability and abundance of natural pastures, by
the absence of predatory insectivores, and by the paucity of small,
grazing competitors. Man-made pastures and settlements in erst-
while forest country are also being added to the range of phyllotines.
Phyllotis darwini and P. micropus have followed man's clearings along
river borders and through forests of Chile and western Argentina.
Zygodontomys is rapidly becoming the common plague rodent in trop-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 15
ical regions where previously forested areas have been transformed
into pastures. Individuals of Phyllotis darwini, P. griseoflarm and
the Mws-like Calomys callosus and C. laucha have invaded man's
habitations. These species compete with introduced murines in
farms, villages and even in large metropolises. They are among
the most successful of indigenous mice and are abundant, often ex-
cessively so, throughout their extensive range. One of them, Calo-
mys laucha, has been accidentally imported into the tropical coastal
areas of northern South America where it is now well established.
This is an extension of range far removed from the natural habitat
of the species in the temperate zones of southern South America.
MATERIAL
Approximately 2500 specimens of phyllotines were examined. Of
these, 2308 are formally listed. The remainder represent Zygodontoniys,
a genus not revised to the subspecies level, though a provisional clas-
sification of its nominal subdivisions is given. Characterization of
the non-phyllotine Euneomys, included in this monograph, is based
on 20 specimens.
Present material represents all but 5 of the 132 described forms
of phyllotines. These 5, and 16 uncritically listed named forms of
Zygodontomys, are included in the total of 60 species and subspecies
recognized as valid. New names have not been proposed here.
\CKNOWLEDGMENTS AND ABBREVIATIONS
Thanks are expressed to the authorities of the institutions listed
below for permission to study and report upon the specimens of
phyllotines in their charge. The following abbreviations for the
names of the institutions are used in the text and lists of specimens
examined.
A MNH = American Museum of Natural History
BM = British Museum (Natural History)
CNHM = Chicago Natural History Museum
LAC M = Los Angeles County Museum
RNHL=Rijksmuseum van Natuurlijke Historie, Leiden
MACN=Museo Argentine de Ciencias Naturales, Buenos Aires
MCZ= Museum of Comparative Zoology, Harvard University
MVZ= Museum of Vertebrate Zoology, University of California
A critical reading of a draft of this manuscript by Professor
Bryan Patterson is gratefully acknowledged. I am specially thank-
16 FIELDIANA: ZOOLOGY, VOLUME 46
ful to Staff Artists E. John Pfiffner and Marion Pahl and Photog-
raphers John Bayalis and Homer V. Holdren for the illustrations.
MEASUREMENTS
All measurements in the tables are given in millimeters. Figures
in parentheses are the extremes, the mean precedes the parentheses,
and the number of samples measured follows.
Cranial terms and measurements are explained in figures 22-26.
Except as noted, external measurements are those of the collectors
and are not uniformly comparable. Unless otherwise indicated,
measurements of "hind foot, dry," include the longest claw and were
taken by the author.
Ordinarily, altitudes and distances are given in the universal
metric system. However, measurements recorded in feet and miles
on specimen labels and in published descriptions have not been
changed in the following lists of localities. Some collectors and
authors have perversely converted into the English system altitudes
and distances originally or officially recorded in the metric system.
To reconvert such measurements here would compound errors of
arithmetic and errors of judgment.
ORIGIN, EVOLUTION AND DISPERSAL
The earliest New World cricetines may have appeared during
early Oligocene or even late Eocene. They may have originated in
Eurasia and ranged into North America, or they may have arisen in
North America and extended into the Old World. Whatever the
place of origin, modern Old World cricetines are relatively few in
kind, specialized in form, and pastoral in habitat. American species,
on the other hand, are highly varied and occupy a diversity of pas-
toral and sylvan niches.
The ancestral form was essentially terrestrial and, judged by pres-
ent habitats of cricetines with unmodified molars, a forest dweller.
Its diet consisted mainly of succulent herbs, fruits, fungi, soft seeds,
shoots, exposed roots, insects, and other small invertebrates. The
molars were characterized by low crowns, a double row of moder-
ately raised and rounded cusps, and three connecting crests, or lophs.
These are the pentalophodont molars described in detail elsewhere
(p. 76). They are designed for efficient mastication of food chiefly
by crushing and pounding motions of the lower jaws. Other char-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 17
acters of the ancestral species include a Mus-tike form and size, tail
approximately equal to combined head and body length, toes well
developed, sole and tail coarsely scutellated, skull delicate and gen-
erally smooth, rostrum moderately elongated, hard palate wide,
comparatively short and unfurrowed, upper incisors simple, slender
and recurved. A Juvenal pelage distinguishable from that of the
adult by its darker color and finer texture is another character of
archaic sylvan cricetines. Although the first cricetines (or nearly
related contemporaries) are not known, they may have been very
much like modern representatives of Thomasomys, or typical Pero-
myscus.
The evolution of cricetines resembles that of horses in several
important respects. Both categories began as forest dwellers in early
Tertiary and both succeeded in spreading over most of the Holarctic
region by late Tertiary. Where rainfall failed and forests were re-
placed by savannas, progressive forms of early equids and cricetines
gradually changed into grazers. The transition from sylvan to pas-
toral life was made possible by the transformation of crested, low-
crowned molars into plane, high-crowned molars capable of with-
standing the attrition of hard grasses and associated grit. In crice-
tines, the higher the molars, the earlier their eruption and function.
This correlation corresponds to the presence and use of milk pre-
molars by young ungulates. Shortening of the nestling stage and
suppression of the distinctive Juvenal pelage in pastoral cricetines
are other adaptive characters. These compare with adaptations of
colts and other new-born grazing mammals which permit them to
fend almost entirely for themselves in competition with adults. 1
1 Vorontsov (1960b, p. 155) believes that the transition from sylvan to pas-
toral habits is also "expressed ecologically in the reduction of the animals' mobil-
ity, in the increase of the total volume of food consumed, in the transition from
nocturnal to 24-hour activity, in the disappearance of the instinct of food pro-
vision. . . . Morphologically, this transition is revealed in the reduction of the
organs of sense (smell, sight, taste), in the simplification of the organs of move-
ment, in the reduction of olfactory lobes of the cerebrum and cerebellum . . .
and essential transformation in the alimentary system."
There is no evidence that the locomotory organs of New World pastoral crice-
tines are less versatile than those of their comparably specialized sylvan counter-
parts. The contrary may even be true in specific cases. All cricetines are nocturnal
and some species are also diurnal. Stresses and environmental pressures frequently
cause diurnality in otherwise nocturnal species. Undoubtedly, pastoral species,
because they are more frequently and easily observed by man, appear to be more
commonly diurnal than sylvan species. Vorontsov's statement that pastoral spe-
cies are losing their instinct for food hoarding must be a mistake of the translator
(I have not seen the original paper in Russian, if published). Pastoral species are,
of course, more regular and consistent storers than sylvan species. Vorontsov him-
self (1960a, p. 983), speaking of Palearctic cricetines, emphasizes that the "features
of their winter biology (food storage and hibernation) permit the present hamster
18 FIELDIANA: ZOOLOGY, VOLUME 46
New World grazing, or pastoral cricetines emerged in three cen-
ters. The first was in the western United States during the Oligo-
cene. Eumys Leidy and Leidymys Wood are two noteworthy products
of the center. The same or similar genera may have migrated into
the second center in Middle America when grasslands were estab-
lished there, not later than early Pliocene. It is more likely, however,
that the Middle American forms arose independently from the same
generally distributed sylvan stock. No fossil records exist to throw
light on this subject. The third center of origin of pastoral cricetines
is in South America, beginning in late Pliocene or early Pleistocene.
The order of invasion of South America by cricetines was determined
by the normal sequence of ecological succession on the Panamanian
land bridge. The first cricetine habitats established were pastoral,
specifically aquatic and palustrine. Savannas, then forests, each with
its fauna, followed. It is significant, then, that the progressive and
specialized pastoral, rather than the archaic and sylvan cricetines
were the first to enter South America. The highly specialized,
aquatic ichthyomyines may have been in the vanguard of the inva-
sion. As forests superseded the grasslands of the Andean and coastal
regions of northwestern South America, pastoral cricetines (except-
ing aquatic forms like Rheomys and Ichthyomys, whose habitats and
modes of life were least affected) were pushed into the savannas of
the Guianas and into the punas and pampas of the southern half of
the continent.
Pastoral cricetines of the Guianan region (including northeastern
Brazil) are the phyllotine Zygodontomys, the sigmodonts, Sigmodon
and Holochilus, and the relict akodonts, Chalcomys, Microxus and
the oxymycterine Podoxomys. All Patagonian cricetines, except the
ubiquitous Oryzomys (Oligoryzomys) nigripes (=longicaudatus), are
pastoral.
Each modern phyllotine species probably originated somewhere
within its present range. The ancestral phyllotine was almost cer-
tainly Middle American in origin. Its identity with Pleistocene (and
late Pliocene?) fossils of the United States, recorded under such phyl-
lotine names as Hesperomys (=Calomys) and Eligmodontia, cannot
to survive. . . ." Differences in the sense organs and central nervous system cer-
tainly exist between many species of cricetines, but a cleavage in these respects
between New World sylvan and pastoral forms has not been shown. Evolution
of a two-chambered stomach in Old World pastoral species from a primitive sac-like
structure such as occurs in New World sylvan Nectomys squamipes was demon-
strated by Vorontsov (1957, p. 526). On the other hand, the stomach of Old World
pastoral Calomyscus and nearly all New World pastoral forms examined by Voront-
sov remains single-chambered.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 19
be demonstrated. What appears, nevertheless, is that molars of pas-
toral cricetines are remarkably similar in all geographic centers of
origin, whether New World or Old World.
CLASSIFICATION AND INTERRELATIONSHIP
Cricetines, including phyllotines, are here regarded as a subfamily
of Muridae. Differences between the Murinae and Cricetinae are
weak and depend almost entirely on whether or not stylar processes
on the inner side of the upper molars are hypertrophied into func-
tional cuspules. The addition of one or more such cuspules results
in the complicated triserial tubercular pattern characteristic of
Murinae as distinguished from the primitive biserial pattern retained
in the Cricetinae. Actually, the difference is no more significant
than the dental ones separating such cricetines as Oryzomys, Pero-
myscus (s.s.), Thomasomys and Aporodon, all with a functional meso-
loph fused with the mesostyle, from other cricetines such as Neotouia,
Sigmodon, Hypsimys, Ichthyomys, etc., without mesoloph and meso-
style. Indeed, the Murinae and all other supergeneric groups of liv-
ing Muridae, save some Malagasy species, diverged from a cricetine
stock in which the mesoloph was being eliminated. Notwithstand-
ing gross differences between the extremes of the groups concerned,
the record of change from species to species, genus to genus and sub-
family to subfamily, is still preserved in Recent forms.
Perhaps more basic than the structure of the molars as a criterion
in the classification of myomorph rodents is the design of the baculum
and glans penis. Two basic types of penes in the Cricetinae, and
possibly in the Muridae as a whole, have been demonstrated by
Hooper (1959, 1960) and Burt (1960). The simple type of penis con-
tains a baculum made up of a bony shaft and a single cartilaginous
segment at the tip. The baculum of the complex type is composed
of a bony shaft with three osseous, cartilaginous or soft tissue finger-
like processes attached to the tip (fig. 5). According to Hooper (1960,
p. 17) the complex or quadripartite baculum with its correspondingly
complex glans penis "is the common and geographically widespread
one. It is predominant in cricetids (sensu Simpson, 1945) in both
the Old and New Worlds, and likely it is typical of murids. It occurs
in Mus, Rattus, Apodemus, Micromys, Acomys, Arvicanthis, NcKokia,
Meriones, Rhambomys, Cricetus, Cricetulus, Mesocricetus, most if not
all microtines, and most if not all South American cricetines [except
Aporodon and Tylomys].
20 FIELDIANA: ZOOLOGY, VOLUME 46
"While the complex plan is widespread, both taxonomically and
geographically, the simple type is restricted to a few North American
kinds. Of the 50 or more genera studied to date, the following twelve
are characterized by simple glandes and bacula; Peromyscus, Reithro-
dontomys [including Aporodon], Neotomodon, Ochrotomys, Onycho-
mys, Baiomys, Scotinomys, Nelsonia, Neotoma, Xenomys, Ototylomys
and Tylomys." This assemblage of genera, concludes Hooper (1960,
p. 19), "has the aspect of a distinct natural unit, of subfamily or fam-
ily rank, which like the Heteromyidae and Geomyidae, is endemic to
the New World. The possibility that it is a natural group now requires
intensive investigation, utilizing all pertinent anatomical data."
That these twelve or thirteen genera comprise a natural group
distinct from other cricetines seems to be confirmed by their cranial,
dental and external characters. The differences between the genera
inter se are typical of radiating forms and each genus could have
diverged from a common Peromyscus-like ancestor. As a result of
convergence, sylvan and pastoral peromyscines strongly resemble
their ecological equivalents among South American cricetines. The
similarities between sylvan Peromyscus of the simple penis group
and sylvan Thomasomys of the complex penis group, however, may
be more than superficial. These genera occupy a position very near
the point of dichotomy between their respective phyletic lines and
their kinship is correspondingly close. On the other hand, resem-
blances between pastoral Baiomys with simple penis and pastoral
Calomys with complex penis are superficial and clearly the result of
convergence. The trenchant differences between these two genera
are discussed elsewhere (p. 126).
The systematic value of the structure of the cricetine penis can-
not yet be fully appreciated or properly interpreted. The penes of
the vast majority of the species and genera remain to be studied and
critically compared and there is no fossil record. What is known of
the differences between the two types of bacula and their glandes is
not imposing. Conceivably, if not predictably, the two types may
prove to be fully intergrading. No other basic anatomical character
absolutely distinguishes any one supergeneric group of murids from
another. Nevertheless, such characters are important and those of
the penis or its parts may be transcendental.
The taxonomic significance of the structure of the cricetine ali-
mentary tract, particularly of the stomach, has been examined by
Vorontsov (1957, p. 526). This investigator demonstrated the pres-
ence of a two-chambered stomach in representatives of all Palearctic
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 21
Cricetinae except Calomyscus. Among New World cricetines he
found a simple sac-like stomach in Nectomys squamipes, Sigmodon
hispidus, Reithrodontomys megalotis and, from published data, in
Peromyscus leucopus, Neotoma floridana and Oxymycterus rujus. In
addition, Vorontsov noted the tendency for the formation of a three-
chambered stomach in Haplomylomys californicus and that the sin-
gle-chambered stomach of Nectomys squamipes most nearly resembled
the postulated primitive cricetine condition (see also footnote, p. 18).
From the foregoing, it is presumed that microtines and South
American cricetines, both with complex glans penis, and peromys-
cines, with simple glans penis, arose independently from a common
cricetine ancestor. The ancestral type may have been very much
like modern Thomasomys with the complex glans penis and a single-
chambered stomach. Presumably, most New World cricetines,
whether sylvan or pastoral, retain the simple stomach. Old World
cricetines and murines may have diverged from a common stock
which, in turn, was itself an independent offshoot from the original
thomasomyine stock. Only Calomyscus among Old World murids
has kept the structurally simple stomach.
Widest cleavage among South American cricetines exists between
forest, or sylvan, forms and their progressive pastoral relatives (fig. 2) .
Morphological differences between the two divisions are of the same
order, though weighed on finer scales, as those distinguishing prim-
itive browsing horses from their grazing descendants. In the case of
murids, however, it is common for certain primitive ancestral stocks
to exist contemporaneously with their modern specialized descend-
ants and connecting relatives.
The older sylvan division includes thomasomyines (Nyctomys, Oto-
nyctomys, Phaenomys, Rhipidomys, Thomasomys [Wilfredomys Avila
Pires, a synonym]) and oryzomyines (Oryzomys [sensu lato], Neso-
ryzomys, Neacomys, Scolomys, Megalomys). In these, each tooth of
the molar series is pentalophodont, i.e., with mesoloph (-id) present
and fused with mesostyl(id) (figs. 4, A; 10, A; 11, A, B; 13). Sylvan
cricetines are primarily inhabitants of broad-leaf forests (selva). The
terrestrial species habitually nest on the ground or in dry burrows.
They may forage in trees, streams and lakes as well as on the forest
floor. Arboreal cricetines nest, feed and breed in trees but some-
times descend for food and water. Semi-aquatic forms nest on the
banks of streams or lakes. There are no fossorial sylvan cricetines.
The pastoral division includes akodonts, phyllotines, sigmodonts,
ichthyomyines, oxymycterines and every other South American crice-
PASTORAL
CHINCHILLULA
' ANDINOMYS
GALENOMYS \
PHYLLOTIS \
^'T V-
ENTALOPHODONT SYLVAN CRICETiNES
FIG. 2.- Interrelationship of the phyllotine genera and their morphological and
ecological relationship to certain other South American cricetines. The progressive
pastoral forms with tetralophodont molars evolved from sylvan pentalophodont
stock. Cricetines with a simple type of penis probably evolved from a sylvan
pentalophodont stock with the complex type of penis.
22
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 23
tine not named above as a member of the sylvan division. Their
molars are simplified, i.e., with mesoloph absent, or, if present, re-
duced and never fused with the mesostyle. The mesolophid is uni-
versally absent or obsolete. The molar pattern is tetralophodont, or
may be reduced to trilophodont, bilophodont or cylindrodont (figs. 4,
B-D; 10, B-F; 11, C, D). Pastoral cricetines inhabit pampas, punas,
llanos, savannas, tundras, scrublands, rock lands, deserts and other
types of grazing and grazing-browsing habitats. They also occur in
thick second-growth woodlots during early serai stages, and in narrow
leaf, or coniferous forests. Most pastoral species are terrestrial and
nest on the ground or in burrows. Semiaquatic forms shelter along
the banks of watercourses. A few species are fossorial and certain
scansorial species have acquired arboreal nesting habits in scrub
country subjected to periodic inundations and destruction of ground
cover usually by burning.
A number of sylvan cricetines may be excurrent elements in pas-
toral regions, especially along streams and gallery forests. Con-
versely, pastoral species may be incurrent in forests where water-
ways, grassy banks or deforestation provides avenues of ingress.
Sylvan and pastoral members of the peromyscine group differ in
the same way as the corresponding divisions of the South American
cricetine group. In some cases, however, species or even subspecies
notably of the genus Peromyscus (cf. Hooper, 1957) appear to be
intermediate between pastoral and sylvan divisions in habitat and
molar design. They are best included in the pastoral division toward
which they are evolving rather than with the sylvan group whence
they departed. Certain other species, such as the woodrat (Neotonia
floridana), with dentition highly specialized for pastoral life, have
acquired sylvan habits in parts of their range.
All microtines and Old World cricetines are pastoral. Their habi-
tats and habits are similar to those of South American pastoral crice-
tines and their dental evolution has followed parallel lines.
Phyllotines belong to the pastoral division of South American
cricetines. They may be recognized chiefly by their generally Mus-
or vole-like appearance, light or moderately heavy skull without
salient modifications, long Oryzomys-Yike palate with conspicuous
posterolateral pits, long slender incisive foramina, and tetralophodont
molars, i.e., molars with mesoloph (-id) obsolete or absent (fig. 4, B).
Phyllotines probably evolved from the same line that gave rise to
akodont rodents. The sigmodonts (Sigmodon, Reithrodon, N colo-
ny s, Holochilus) are more specialized but appear to be progres-
24 FIELDIANA: ZOOLOGY, VOLUME 46
sive offshoots from the main phyllotine line. The Neotropical fish
eaters typified by Ichthyomys and Rheomys, also with basic tetra-
lophodont molars, are highly specialized derivatives of pastoral forms.
The insectivore-like oxymycterines represent still another radiation
of basic pastoral stock (fig. 2).
Phyllotines are separable into two sections. The more primitive
Calomys section includes the buno-brachyodont Calomys, Eligmo-
dontia and Zygodontomys. The Phyllotis section, with high-crowned,
terraced or planed molars (fig. 14), consists of Phyllotis, Pseudory-
zomys, Galenomys, Andinomys and Chinchillula. The Mus-\ike
Calomys sorellus and C. laucha are the most generalized and smallest
members of the phyllotine group. The microtine and hamster-
like Andinomys and Chinchillula, respectively, are the most special-
ized and largest. External and cranial differences between the ex-
tremes are hardly more trenchant than those separating species and
subgenera. On the other hand, dental differences between Calomys
and either Andinomys or Chinchillula are of the same order as those
distinguishing a browsing buno-brachyodont ungulate of the Oligo-
cene from its modern grazing platy-hypsodont descendant. In phyl-
lotines, however, evolution in dental topography from low crown to
high crown, from crested to plane, from tetralophodont to bilo-
phodont (fig. 10), can be traced as a gradual transition through
living species.
Besides the generalized tetralophodont dental pattern, the species
of Calomys exhibit in their crania the two basic supraorbital types
(fig. 23) found in cricetines. One is with parallel- or concave-sided
supraorbital region, the other with divergent-sided supraorbital
region. All generalized external characters of phyllotines are found
in Calomys. It may be assumed, therefore, that the pre-phyllotine
ancestor differed little in external and cranial characters from such
forms as Calomys sorellus and C. laucha. The ancestral molars, how-
ever, must have been marked by the presence of a well-developed
mesoloph. This is requisite for derivation of phyllotines from the
basic pentalophodont cricetine stock.
The remarkable resemblance between Calomys and the distantly
related tetralophodont Baiomys of North America is principally
superficial and appears to be the result of convergence (cf. p. 126).
Certain gross resemblances between phyllotines and South African
Mystromys (cf. p. 221) are obviously the result of parallel develop-
ment of widely separated lines of murids.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 25
The most specialized phyllotines grade into the sigmodont group
(for characterization see Hershkovitz, 1955, p. 640).' Molars of
sigmodonts are, in general, more advanced, with the enamel folds
more compressed and tending toward lamination. The palate and
the pterygoid region are more complicated, the zygomatic plate ex-
tremely developed. Externally, sigmodonts, which have developed
such well-defined vole-like, aquatic, and leporine types, may be
nearing the end of their adaptive radiation.
External, cranial and dental criteria for classification of the
cricetines mentioned above are discussed under separate headings
below.
ADAPTIVE RADIATION
The repeated establishment of meadows, prairies, tundras and
coniferous forests in the wake of the several glacial retreats in the
northern hemisphere provided the stages for explosive developments
of pastoral murids from sylvan stock. With the close of the last
glacial period, pastoral forms diversified into many types, each
adapted to a special niche.
Notwithstanding differences in general environment, diet and
masticatory systems, adaptive radiation in pastoral species was
remarkably similar to that of sylvan species where newly invaded
habitats resembled sylvan habitats. In the case of Neotropical
cricetines, the semiaquatic, pastoral marsh rat, Holochilus, is almost
indistinguishable in external and cranial characters from its sylvan
counterpart, the oryzomyine rat, Nectomys squamipes. Pastoral
but semiarboreal Phyllotis griseoflavus mimics its sylvan opposite
numbers among scansorial or more or less arboreal species of Thoma-
somys, Peromyscus (Megadontomys) and Oryzomys (Oecomys) concolor.
Not only do these species agree in body size, proportionate tail
length and limb modifications; they have also developed a broad,
divergent-sided supraorbital region. Truly arboreal pastoral forms
comparable to sylvan Rhipidomys, Nyctomys and Tylomys do not
exist. Among hystricomorph rodents, however, the grazing-brows-
ing species of Dactylomyinae nest and feed in the evergreen pastures
of bamboo grove canopies; presumably, the ancestral dactylomyines
left the ground when their terrestrial habitat was subjected to pro-
tracted floodings or was choked by superseding forests. The most
1 In the description of the cranial characters of the sigmodont rodents, the
anterior border of the zygomatic plate is said to be "convex" (loc. cit., last line).
The term should read "concave." See plate 29 of the cited work.
26 FIELD IANA: ZOOLOGY, VOLUME 46
common pastoral cricetine types are vole-like phyllotines, akodonts,
etc. The sylvan counterpart is Oryzomys caliginosus. Perhaps be-
cause of the abundance of moist, dark cover on forest floors or
because of periodic flooding in many parts of their range, sylvan
cricetines have not become specialized for subterranean life. At
best they are weak burrowers. In contrast, the pastoral akodont
Notiomys, with stout limbs, long claws, minute ears, and thick coat,
is well adapted for a burrowing life. Pastoral Oxymycterus, Thap-
tomys, and Bolomys are subfossorial, and Blarinomys is the extreme
example of talpine form and habits among cricetines.
The majority of phyllotines are generalized pastoral types. None
is fossorial, although most phyllotines do occupy, whether for refuge
or nesting, burrows made by other animals. Only the monotypic
phyllotine Pseudoryzomys is sufficiently modified for aquatic life for
comparison with such semiaquatic cricetines as Oryzomys palustris
Zygodontomys, notably in its fan-shaped hind foot, also bears some
resemblance to large palustrine types of oryzomyines. Zygodonto-
mys, however, is basically vole-like and apt to be confused with the
similarly vole-like Sigmodon, with which it shares habitats where the
ranges of the two overlap. Indeed, the microtine or hamster-like
form has been the principal evolutionary line of adaptation followed
by phyllotines. Phyllotis sublimis, P. boliviensis, Galenomys garleppi
and tiny Calomys lepidus, all of the Andean highlands, are short-
tailed vole-like inhabitants of grass and rock communities. The last
species superficially resembles species of Old World Cricetulus. The
most remarkable hamster-like phyllotine is the large, heavy-bodied
and variegated Chinchillula sahamae, of the same habitat.
Eligmodontia typus has radiated in a direction unique among
phyllotines and New World cricetines in general. It is remarkably
gerbil-like in color, size, shape of body, specialization of hind legs
and feet, and choice of habitat. The Piura desert mouse, Phyllotis
gerbillus, is similar in size, color and habitat but its limbs are not
gerbil-like.
A third type of adaptive radiation among phyllotines is the semi-
arboreal. Phyllotis griseoflavus has already been mentioned as the
example. This species nests on and above the ground but is pri-
marily a ground feeder. Ability to climb is in itself a generalized
phyllotine character.
The vaulted skull and proodont upper and procumbent lower
incisors found in the vole-like phyllotine Galenomys garleppi of the
high Andes are characters pointing to leporine habits. Similar char-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 27
acters exist in the Arctic hare, Lepus arcticus. The habitats of both
animals are also similar.
JUVENAL CHARACTERS AND DEVELOPMENT
In grassland cricetines the first post-natal pelage is essentially
as in adults, though it is usually thinner, paler, and more grizzled on
the upper parts and sides of the head and body. Molt from Juvenal
pelage to typically adult pelage is generally unmarked by lines of
transition and is completed during an early stage of development,
possibly at weaning.
Growth of tail, hind foot, and ear in young individuals is faster
than growth of head and trunk. After sexual maturity, the extrem-
ities have attained almost maximum size and their rate of growth
declines sharply. Growth of head and body, on the other hand, con-
tinues apace throughout life. Measurements reveal that in any one
population extremities of juvenals and subadults are proportionately
larger than in adults of the same population, and that differences in
skull lengths between young and extremely old adults are greater
than between young adults and weaned juvenals.
Breeding begins at a growth stage when cranial characters would
be subadult or even Juvenal. Sexual maturity precedes anatomical
maturity in all mammals but pastoral mice are particularly pre-
cocious breeders.
The braincase is proportionately larger, the supraorbital region
broader in juvenals. In some phyllotines, notably Phyllotis griseo-
flavus, Calomys callosus and Zygodontomys, the broad Juvenal supra-
orbitals have been retained in the adult and have developed beaded
projecting ledges.
The young of most phyllotines acquire a fully erupted and func-
tional set of molars while still suckling. This phenomenon provides
maximum molar surface in response to an early need for grinding
siliceous grasses and other harsh, highly cellulose plants. The newly
erupted hypsodont or subhypsodont molar is pyramidal in form. As
a consequence the grinding surface of the tooth increases with wear
concurrently with the growth of the mouse and its need for more
food. Some dental elements, such as the mesoloph, normally absent
in the adult molars of phyllotines, may be present, though weakly
developed, in the newly erupted third molar. Conversely, dental
characters of a caenogenetic nature may also appear in the unworn
or unerupted third upper molar. Some such characters are ephe-
28 FIELDIANA: ZOOLOGY, VOLUME 46
meral and of no significance beyond the brief span of their existence.
Others may have some selective value and may develop into impor-
tant factors in the economy of the adult.
The fully adult pelage and dentition acquired at an early age by
juvenals of most phyllotines contrast sharply with the distinctively
dark pelage and retarded last molar in juvenals of forest-dwelling
cricetines with the primitive, or pentalophodont, type of molars.
REPRODUCTION
In Neotropical regions with well-defined seasonal fluctuations in
temperature, breeding activity among cricetines is greatest in sum-
mer (December-March) and least in winter (June-September).
Breeding becomes more nearly uniform throughout the year in
latitudes nearer the equator. Here, too, some periodicity may be
maintained locally, but mating does not take place at the same time
in all localities. In effect, reproduction, like molt, is uninterrupted
in species occupying geographic ranges which embrace highly diversi-
fied but locally constant climates.
The condition of the mammae in skins of specimens examined
indicates that from two to at least four litters are produced annually
by the adult female of all species of Phyllotis. According to col-
lectors' data, a litter contains from three to ten young. Litter sizes
and reproductive rates in phyllotines are comparable to those of
cricetines of the Temperate Zone of North America.
Data on sexual behavior, compiled from the literature, are given
in the accounts of individual species.
POCKET POPULATIONS
Small mammals of a sedentary nature, such as most phyllotines,
are often distributed in pockets, when their population is at mean or
low levels. A pocket is a small isolated ecological community in-
habited by an inbreeding population, or colony, of animals. The
pocket ordinarily contains all elements needed for maintaining its
resident population and is usually sufficiently diversified ecologically
to include a number of niches. A desert oasis and an alpine meadow
are examples of pockets in so far as concerns the small mammals
restricted to each. A bamboo grove or a wood-lot surrounded by
grassland or swamp or, conversely, a pasture or swamp surrounded
by forest, each with its special complement of resident animals,
are also examples of pockets.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 29
The actual size of a pocket is related to the size and mobility of
its residents. A pocket in terms of a cricetine rodent is not a pocket
in terms of a large ungulate or carnivore. On the other hand, micro-
scopic organisms infesting a pocket of mice are also residents of pre-
cisely the same pocket. Here the focus of infection and the pocket
are identical and the parasites are subject to the same dynamics of
the pocket as their hosts.
The size of the population depends on the carrying capacity of
the pocket. Usually, fluctuations in population are directly related
to fluctuations in food supply. Rate of reproduction, predation, dis-
ease, seasonal changes in climate and terrain are controlling factors.
At times of extraordinary abundance of food the population of a
pocket may grow to exceed by several times the ordinary carrying
capacity of the range. With swift termination of the special food
supply most of the population erupts into the inhospitable country-
side in search of nourishment. Nearly all migrants die within days
(see ratadas, p. 42). A few return to their original pocket. Others
may breach barriers and find other pockets where they may either
be absorbed by established colonies, if any, or start new colonies.
The stability of a pocket population is relative. Its isolation may
break down during population explosions or other crises. Floods not
only have the power to destroy but may also be the agents for trans-
porting individuals from one pocket to another or for seeding new
pockets. Predators or disease may wipe out the population of a pocket
and fires may destroy the pocket as well as its population. Pockets
themselves may be early serai stages and each major change in suc-
cession often involves the displacement or replacement of the earlier
pocket population. Cultivation of land by man regularly results in
the establishment of new pockets and the destruction or modification
of old ones. As pockets expand their populations expand. Two or
more pockets which grow and join to form one large subclimax or
climax merge their populations into one race. Secondary fragmen-
tation of the climax redivides the racial population into relict pocket
populations.
The pocket population is the basic stock for experiments in evo-
lution and the pocket is the primary testing laboratory. The pop-
ulation of a relict pocket is, perhaps, the most stable for experimental
purposes and the relict pocket itself provides the most uniform selec-
tive pressures for testing new characters or new combinations of char-
acters. When the population is low and the reproductive rate high,
the establishment of a trait throughout the pocket population can
30 FIELDIANA: ZOOLOGY, VOLUME 46
be rapid. When the population is at an eruptive peak, diffusion of
the trait throughout the range of the race or species becomes possible.
The rate of evolution is measured in generations, not calendar
years. Pocket populations of small rodents such as phyllotines breed
early, usually within one month of birth, and several times each year.
The average life span of the individual, however, is less than 6 months.
This combination of fecundity and longevity results in rapid popu-
lation turnovers with a minimum of ancestral genetic drag.
The diagnostic characters of old established neighboring pocket
populations may be concordant where ecological conditions are sim-
ilar, discordant where they are notably different, or clinal where they
are varied or intermediate. Differences between allochronic but
sympatric populations may be of the same order as differences be-
tween synchronic but allopatric populations.
Montane mammalian populations that occupy pockets at the
highest altitudinal levels may be called pinnacle populations. They
are derived from and may retain their connection with the mass of
the species population at lower levels. Pinnacle populations of the
same mountain system generally develop along parallel or convergent
lines but the relationship between them is through the parental stock
at lower levels. Where the parental stock has disappeared each pin-
nacle population becomes a relict evolving along independent lines.
Oasis populations are usually of waif or accidental origin and
their superficial characters are generally concordant, their under-
lying ones usually discordant.
Peripheral pocket populations inhabit the outer borders of the
range of the species or subspecies. The diagnostic characters of these
populations are apt to be clinal, with each population, in the case of
subspecies, interbreeding almost or quite continuously with the neigh-
boring populations of the same or related subspecies.
A species or subspecies generally includes a number of discordant
as well as concordant and clinal pocket populations. There are,
nevertheless, valid subspecies and even species (cf . Phyllotis gerbillus)
with their respective geographic ranges restricted to a single pocket.
Basic data for these generalizations on pocket populations are
contained in the following accounts of variation between the sub-
species of Phyllotis darwini, P. osilae and others. The habitats of
local populations of Phyllotis described by Pearson (particularly in
his section on sympatry (1958, pp. 397-405) are, in many instances,
examples of pockets.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 31
SYMPATHY AND ALLOPATHY
The practical concept of sympatric is taxonomic, not biogeo-
graphic. The word, however, can refer to any and all organisms
occupying a common geographic area. In order to conserve and em-
phasize the taxonomic sense of sympatric, a restricted form of the
term must be used for representatives of sibling species or different
subspecies of the same species whose trails cross during the course
of their ordinary movements. A more precise term for this form of
sympatric relationship is synecetic, proposed by Harper, et al. (1961,
p. 211). Thus, all synecetic representatives of species or subspecies
are sympatric but all sympatric representatives of species or subspe-
cies are not synecetic. Two mammalian subspecies with ranges which
interdigitate but do not overlap may be regarded as sympatric but
cannot be classified as synecetic. The geographic ranges of fossorial,
terrestrial, aquatic and arboreal species of mammals may all over-
lap) actually they would form a mosaic but if the animals them-
selves do not ordinarily cross trails they are not synecetic.
Sympatry, when it occurs, follows divergence of the species or
subspecies in geographic isolation. Sympatry may endure for the
life of all but one of the coexisting taxons, or it may be cyclical or
ephemeral. The spatial ebb and flow of otherwise geographically
contiguous or narrowly separated taxons may result in periodic or
rare overlappings in range. Migratory species coexisting transitorily
with closely related forms are not true sympatriants. A misleading
simulation of sympatry may result from the mingling, during an
eruption, of two or more well-defined and erstwhile geographically
isolated pocket populations.
Sympatric taxons may or may not be reproductively isolated
but synecetic taxons are necessarily so. Sympatry, or syneceticity
between two or more taxons, is generally regarded as prima facie
evidence for their specific separation. There are, however, notable ex-
ceptions among mammals, including the rodents under consideration.
Allopatric, the antonym of sympatric, could be correspondingly
restricted to geographically contiguous sibling (cognate) species or
subspecies. Use of the term for widely separated taxons of any
grade dilutes or nullifies its special taxonomic implications.
The intimately related and similar-appearing members of the
Phyllotis darwini complex offer prime examples of the significance of
sympatry and allopatry in taxonomy. All other phyllotines can be
classified on the basis of morphology alone.
32 FIELDIANA: ZOOLOGY, VOLUME 46
The northernmost member of the Phyllotis darwini group is Phyl-
lotis haggardi of the Ecuadorian Andes. It is treated as a full species
on the basis of seemingly trivial yet consistent characters which dis-
tinguish it from its nearest geographic ally, Phyllotis andium. Pres-
ent data indicate that haggardi and andium are completely allo-
patric (fig. 72), but the nearer they are geographically the more
similar they appear to be. Whether the cline is a product of con-
vergence or of intergradation is a question that cannot be answered
conclusively without the test of sympatry.
In contrast with the above, specific separation of Phyllotis andium
from P. darwini depends entirely on evidence of sympatry. The
former is recorded as coexisting in central Peru with three subspecies
of the latter. The differences between P. andium and sympatric
populations of P. darwini limatus, and sympatric and at least one
synecetic population of P. d. posticalis are not impressive. They
may be greater than between some allopatric populations of the same
taxons including P. andium and less than others including P. andium.
On the other hand, P. andium differs grossly from P. darwini defi-
nitus with which it coexists in the only locality where the latter is
known to occur. Whatever the nature of the differences, where an-
dium and darwini are sympatric they do not intergrade and where
they are allopatric they cannot interbreed.
Two subspecies of the same species, P. darwini rupestris and
P. d. magister, coexist in southwestern Peru without intergradation
(fig. 73). Unlike the preceding example, where these races are
allopatric they can and do intergrade through an intermediate sub-
species. The larger race, Phyllotis darwini magister, is a poorly de-
fined, questionably separable western Andean extension of P. darwini
posticalis. P. d. rupestris also seems to stem from posticalis stock
but it has spread southward along the eastern slope of the moun-
tains and has become significantly smaller and paler. Where rupestris
meets magister, differentiation of the former already has reached the
point of reproductive isolation from the latter. Inasmuch as both
rupestris and magister grade into posticalis, all are regarded as con-
specific.
On the opposite side of the Andes in southern Bolivia and north-
ern Argentina, Phyllotis darwini rupestris and P. d. caprinus are fully
intergrading, though their ranges may overlap at some points. The
available evidence, meager and unverified as it is, indicates that the
two races are not synecetic (figs. 74, 77).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 33
The most interesting and perplexing case of sympatry among
phyllotines is that between Phyllotis darwini and P. osilae. The
range of osilae extends as a narrow band along the eastern Andes
from central Cusco, Peru, in the north to southern Catamarca,
Argentina, in the south (fig. 74). Representatives of osilae and
darwini are recorded as sympatric in 25 localities distributed over
the entire length of this range. Two subspecies of P. osilae and
four of P. darwini are involved. Whether or not the two species
are actually synecetic in any one locality is moot. Pearson (1958,
p. 399) believes that "sympatry of these morphologically similar
forms is based upon different habitat preferences." 1 If this is true,
the case for regarding osilae and darwini as distinct species rather
than sympatric subspecies is considerably weakened.
The greatest number of sympatric series are concentrated in the
Lake Titicaca drainage basin in Puno, Peru. They represent sub-
species Phyllotis osilae osilae and P. darwini rupestris. The number
of specimens in the sympatric pairs ranges from one osilae and two
rupestris from Puno, Puno, to eighteen osilae and three rupestris from
Pairumani. The best numerical representation of the two species is
the series from Chucuito, which consists of five osilae and eight
rupestris. In no case are the sympatric series large enough to use
for calculating the full range of their respective variation. The dif-
ferences between the species are subtle, and the larger the sympatric
series of osilae and rupestris the fewer and narrower the differences
become. In any case, sympatric populations of osilae and rupestris
are more nearly alike than allopatric members of the same races.
Differences between P. osilae osilae and P. darwini posticalis re-
corded from three sympatric localities in Cusco, Peru, are fine enough
to be overlooked or dismissed as insignificant by the unwary taxono-
mist. Differences between allopatric populations of these subspecies
are of the same order or greater, never less.
P. osilae pkaeus is easily distinguished from a peripheral series of
P. darwini posticalis and the differences between allopatric popula-
tions may be greater or less.
1 This statement appears to be based on impressions of random trapping results
rather than on a scientifically conducted census. Pearson does not relate his catch
to the number of trap nights or supply information regarding his trapping methods.
The reader is left to believe that other conclusions might be reached by other col-
lecting methods or by other collectors. Judged by data on the labels of his speci-
mens, Pearson's trapping consisted of one or two night stands in each of the vast
majority of localities worked. The trapping sites were generally along highways or
railways in areas with ecologies repeatedly disturbed and constantly controlled by
man during one or two millenniums.
34 FIELDIANA: ZOOLOGY, VOLUME 46
The third concentration of sympatric localities is in central Bo-
livia, where the range of the localized Phyttotis darwini wolffsohni
sprawls over a section of the range of P. o. osilae. The sympatric
populations of the two forms are similar superficially but differ in
size and in cranial and dental characters. The differences between
the two species here are greater than elsewhere irrespective of the
races compared or their geographic relationship. Nevertheless, the
tendency toward convergence in sympatry is so strong among phyllo-
tines that P. darwini wolffsohni more nearly resembles sympatric
populations of the species P. osilae than it does the nearest geo-
graphic representatives of the subspecies Phyllotis darwini rupestris
with which it intergrades through P. d. caprinus.
Not one of the characters that serve to separate sympatric repre-
sentatives of osilae from darwini is valid for distinguishing all osilae
from all darwini. The differences between sympatric populations are
of the same order as differences between pocket populations and sub-
species of either species. There is no evidence of intergradation be-
tween osilae and darwini where they are sympatric, and there is no
evidence that a population of one species of a sympatric pair inter-
grades with an allopatric (i.e., contiguous) population of the other
species (cf. Tables 30-49).
Where sympatric osilae and darwini are most nearly alike, their
resemblance suggests either a recent and comparatively slight diver-
gence from a common ancestor or a convergence in sympatry after
initial differentiation in geographic isolation. Absence of inter-
grades or hybrids points to the latter explanation as more plausible
if not most probable.
Representatives of the two species that differ most in sympatry
occur at the far extremes of their respective geographic ranges.
Their greater divergence involved movements over greater distances
through more diversified environments during longer periods of time.
Nevertheless, where they meet, the species tend to converge in super-
ficial characters at least.
All the foregoing runs counter to character displacement defined
by Brown and Wilson (1956, p. 63) as "the situation in which, when
two species of animals overlap geographically the differences between
them are accentuated in the zone of sympatry and weakened or lost
entirely in the parts of their ranges outside this zone. The charac-
ters involved in this dual divergence-convergence pattern may be
morphological, ecological, behavioral, or physiological. Character
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 35
displacement probably results most commonly from the first post-
isolation contact of two newly evolved cognate species. Upon meet-
ing, the two populations interact through genetic reinforcement of
species barriers and /or ecological displacement in such a way as to
diverge farther from one another where they occur together. Ex-
amples of the phenomenon, both verified and probable, are cited for
diverse animal groups [none mammalian] illustrating the various
aspects that may be assumed by the pattern."
Divergence in allopatry, i.e., in different but contiguous ecologies,
and convergence in sympatry, i.e., in the same broad ecology, are an
evolutionary pattern quite the reverse of "character displacement."
This pattern is not peculiar to members of the Phyllotis darwini com-
plex. It is common among closely related mammals of all orders.
As a rule, convergent characters in sympatry are superficial, usually
adaptive, and superposed on the valid diagnostic characters of the
species. They are, in effect, similar, if not identical, responses of
closely related species to the same environment. On the other hand,
truly distinctive specific characters are those which evolve in allo-
patry as unique responses of the organism to its peculiar environment.
The degree of divergence depends on the period and circumstances
of geographic isolation and not at all on a mechanism which is trig-
gered by the first post-isolation contact as suggested by Brown and
Wilson. Divergent populations which make contact on common
ground after reproductive isolation has been attained, may continue
to diverge, and they probably do in some respects. The more im-
portant and stronger tendency, however, is toward convergence. 1
The basic specific characters, which evolved in allopatry, become
stabilized in sympatry.
The great amount of variation and the instability of the charac-
ters or combination of characters distinguishing sympatric popula-
tions of osilae and darwini suggest that the species themselves are
not stable. It is not improbable that future collecting will reveal
the existence of one or more intergrading populations. Meanwhile,
Phyllotis osilae is regarded as something less than a full species but
more than the conventional subspecies; hence the binomial. Its posi-
tion as an infraspecific category, however, coordinate with the com-
1 This statement is not to be interpreted as a denial of the fact that many sib-
ling species do differ most in sympatry. I myself (1960, p. 529 and pi. 5) pointed
out that sympatric representatives of the cricetines Oryzomys (Oecomys) concolor
and O. (O.) bicolor are easily recognized, but that some allopatric individuals of the
same species may be indistinguishable. Additional examples among mammals can
be cited, but nothing known of the evolution of these paired species supports the
concept of "character displacement."
36 FIELDIANA: ZOOLOGY, VOLUME 46
parably ill-defined Phyllotis andium and P. haggardi, is indicated by
inclusion of osilae in the Phyllotis darwini complex.
Sympatry also occurs between Phyllotis darwini and its most
nearly related congeners outside the complex. The range of the
western Peruvian Phyllotis amicus overlaps that of P. darwini pos-
ticalis, but nothing is known of the habits of the latter. The mor-
phology of P. darwini and P. griseoflavus suggests some ecological
segregation where they are sympatric. The two species, however,
are evidently synecetic, and individuals of both have even been found
in the same burrow. P. darwini has also been found in common col-
lecting localities with the Patagonian P. micropus but it is assumed
this occurs where man has altered the habitat of the second to per-
mit invasion by the first.
Calomys, the only other undoubted polytypic phyllotine genus,
comprises four species. Where their ranges overlap, C. laucha is
the pampa mouse, while the larger C. callosus is restricted to gallery
and scrub forests. Calomys sorellus and the smaller, shorter-tailed
C. lepidus have been taken in the same localities in Peru. It is
virtually certain that they, too, are ecologically segregated.
CROP VARIATION
No two generations of a population develop in the same way and
at the same rate. Most common differences between generations, or
crops, are in size, weight, pelage, color, reproductive rate, and
population density. Such differences between generations, or sea-
sonal crops, of the same population are expressions of crop variation.
The young of grazing cricetine rodents, including phyllotines,
acquire adult characters and habits precociously as compared with
the young of forms that undergo a prolonged development in the
comparatively stable environment of maternal nest, den or burrow.
Phyllotines born during the dry season are promptly exposed to
rigorous living conditions. Available food may be barely sufficient
to supply the young animal with energy needed for foraging and for
maintaining body weight commensurate with increasing size. On
the other hand, phyllotines born in the rainy season may be literally
bedded in an abundance of tender shoots of succulent plants. The
quantity and quality of such food, combined with the ease with which
it is taken and eaten by the mouse, must contribute to development
of potential maximum in size of skeletal and dental parts. Thus, an
individual born and developed during the fruitful rainy season may
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 37
be larger, and, because of less molar abrasion, erroneously adjudged
younger, than a comparably aged product of the barren dry season.
When phyllotines of one local crop survive several seasons no
doubt they tend to appear like old adults of other crops of the same
locality. Few small rodents, however, live through the combined
life spans of two or more successive crops. The average life span of
cricetines in nature is less than six months. Blair (1948) calculated
the longevity of wild living individuals of comparable Michigan
Peromyscus maniculatus, P. leucopus, and Microtus pennsylvanicus,
as varying from four to five months. Snyder (1956, p. 27), using
finer methods, determined the average life span of Peromyscus
leucopus as five months. Hence, a phyllotine may be born, reach
sexual maturity, reproduce and die during the three to six months
duration of a normal dry or rainy season anywhere within its range.
No field studies of crop variation in phyllotines have been made.
However, results of an 11-year investigation of cyclical fluctuations
in the cotton rat (Sigmodon hispidus) population of a fallow field in
Georgia, are pertinent. The investigator, Odum (1955) found that
"cotton rats appear on the runways when a week or less old . . . and
begin to breed when two months or less in age. . . . Since few indi-
viduals may be expected to live more than six months, the population
turnover may often be complete every six months. With a species
such as the cotton rat which begins to breed at an early age and
rarely lives long enough to reach maximum size it is clear that
average measurements of 'adults' will vary according to the stage in
the population oscillation. . . . Therefore, size should not be used as
a criterion for the establishment of geographic races or subspecies
unless the sample is very large and the stage in the population cycle
from which it was taken is known."
A study by Martin (1956, p. 388) of a Kansas population of the
prairie vole (Microtus ochrogaster Wagner) revealed that during an
unusually dry summer reproduction was inhibited, adult voles lost
weight, and young born in the spring ceased to grow. Fitch and
Rainey (1956, p. 528) conducted a similar study of the eastern
woodrat (Neotoma floridana Ord) and found that "growth rate and
adult weight are influenced to a large extent by season." They did
not overlook the importance of individual differences as controlling
factors.
In the works cited above, organic variations are correlated with
population cycles, and with seasonal changes in the quantity and
quality of the food supply, temperature, and rainfall. The impor-
38 FIELDIANA: ZOOLOGY, VOLUME 46
tance of food alone among wild brown rats (Rattus norvegicus
Berkenhout) was determined experimentally by Calhoun (1949,
pp. 1113-1122). The rats were kept in a specially designed pen.
Those born near the abundant and continuously maintained food
supply grew more rapidly, attained larger size, and were higher in
the social order than those born farther away.
Other field studies of less nearly related mammals support the
concept of crop variation. Scheffer (1955, pp. 493-513) was pri-
marily concerned with the relationship between body size and nu-
merical abundance in seals. He also reviewed some of the literature
regarding the same relationship in the brown rat, house mouse, vole,
muskrat, gray squirrel, raccoon, deer, and man. As a corollary,
Scheffer noted (op. cit., p. 513) that "body size is, of course, not only
a genetic product but a quantitative measure of environmental
response. When certain body characters vary significantly in size
from those of the generation closely removed, it may be argued that
here are members of two 'races' separated only by a thin partition
of time. The argument is unrealistic but it does make a point:
where slight differences are critical, the systematist should choose
samples for comparative study taken from similar population density
environments. This precaution extends the meaning of Cazier and
Bacon (1949 [Bull. Amer. Mus. Nat. Hist., 93: 343-388]): The
specimens should be from similar climatic, edaphic, and biotic
situations . . . taken within a limited range of time so as to preclude
possible confusion resulting from contamination by seasonal vari-
ance.' ' Here I must interpose that the systematic mammalogist
can deal only with the material at his disposal and has little or no
knowledge of particular habitats or population densities. He need
only learn to discount crop and other levels of intraspecific variation
in evaluating the taxonomic status of the sample.
Environmental factors that combine to modify each crop are
separated in time from those modifying the next crop. Modifications
within a crop produced by environmental factors separated in space
are discussed under the next heading.
NICHE VARIATION
Differences between individuals living in one section of the range
of a population and individuals of the same species inhabiting
another section of the same range are expressions of what is here
termed niche variation. Calhoun's experiment with brown rats,
cited above as an illustration of crop variation, is also a valid demon-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 39
stration of one kind of niche variation. Likewise, individuals or
small colonies of phyllotines living nearest the best food supply can
reasonably be expected to be better developed than their neighbors
not as favorably stationed. Certain phyllotines, notably Phyllotis
darwini and Calomys laucha, reside in human dwellings, storehouses,
well-watered gardens, refuse dumps and similar habitats with a
suitable and permanent food supply. Inhabitants of such special
niches can acquire somatic characters that distinguish them from
members of the same population, or crop, living in natural and less
favored surroundings of the immediate vicinity. Some of the strik-
ing morphological differences distinguishing neighboring colonies of
tuco tucos (Ctenomys) and similar burrowing rodents (Thomomys,
Tachyorycles, etc.) may be no more than manifestations of niche
variation.
An investigation of house mice (Mus musculus} inhabiting four
different environments revealed manifestations of niche variation.
It was shown by Laurie (1946) that the mice in cold stores where
the temperature never exceeded 15 F. lived normally, bred and
produced regularly the year round, had more embryos, and were
larger and heavier than mice of the other three habitats. The cold
store mice ate meat exclusively. Mice of corn ricks had the highest
rate of productivity, while those of urban habitats had the lowest.
Mice living in flour depots were average producers. Their food
consisted of white flour only. This diet may have been the cause of
a skin condition characterized by thin pelage, bald patches, and
torn and crumpled ears. A minority of the mice was affected and
most of them lived in the same depot. The mice of the four environ-
ments were taken from a number of places in London, Oxford and
other localities. For all taxonomic purposes, however, the environ-
mentally different habitats could have been adjacent rooms in a
building in Oxford where most of the urban rats were trapped.
Striking differences in color may also be manifestations of niche
variation. The unusually pale color in two species of bats, Tadarida
brasiliensis and Myotis velifer, living in certain Texas caves is the
result, according to Constantine (1957, p. 465), of the bleaching effect
of environmental ammonia gas and water vapor. Later Constantine
(1958, p. 513) confirmed his conclusions by reproducing experimen-
tally the bleaching effect of ammonia and high humidity on live
Tadarida.
The distinction between crop and niche variation is blurred or
erased in nearly all experiments in which attempts are made to deter-
40 FIELDIANA: ZOOLOGY, VOLUME 46
mine the effects of environment on organic growth and development.
Nevertheless, such experiments often produce significant differences
between the test animals and sometimes suggest the kinds of differ-
ences which might exist in nature between groups of individuals of
the same population separated in time or space. In one experiment,
Ogle (1934a, p. 628) found that female white laboratory mice sub-
jected to a warm (31-33 C.), humid (75%) environment had fewer
fertile matings, smaller litters and less viable offspring than mice of
the same strain kept in a uniformly cool (17.8 C.) environment.
The males (Ogle, 1934b, p. 635) in the warm moist room developed
very short and slender bodies but the tails of each were 1 cm. longer
than combined head and body length. Males acclimated in the cool
room increased in body weight and length at practically the same
rate as the control mice kept at 21-27 C. Their tails, however,
were 1 cm. shorter than combined head and body length. In a sim-
ilar experiment by Biggers, Ashoub, McLaren and Michie (1958,
p. 144), who used different hot and cold environmental temperatures,
the results were generally the reverse. Females in hot (28.09 C.,
87% humidity) and cold (4.78 C., 77.48% humidity) environments
had a higher mortality of prenatal and postnatal young than females
in the temperate or control (21 C., 69.03% humidity) environment.
Furthermore, "no significant differences in rate of growth or develop-
ment were found between the mice in the hot and temperate environ-
ments. Both growth and development were markedly retarded in
the cold."
Changes in the gross appearance and chemical composition of the
teeth of rats may also be induced by chronic exposure to adverse en-
vironments. Harris, Mefferd and Restivo (1960, p. 476) showed that
the incisors in rats acclimated for 3 to 6 months at a temperature of
36 C. usually acquired a heavy reddish-brown deposit. The incisors
in rats maintained at a high altitude (380 mm. Hg.) remained normal.
Food intake, hence masticatory activity, was approximately the
same in the heat and altitude groups. Rats exposed to a combina-
tion of heat and high altitude revealed significantly reduced concen-
trations of calcium, phosphate and magnesium in their incisors.
As a final example, Harrison (1958, p. 892) investigated such
characters as longer tails, larger feet, thinner pelage, smaller body
size and general acclimatization of mice (Mus musculus) subjected
to a hot environment by a number of experimenters including Ogle
(1934b, p. 635), mentioned above. Harrison concluded (p. 900) "that
at least some of the changes, both physiological and morphological,
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 41
which occur when mice are reared at high temperatures, are in their
over-all effect adaptive."
Trapping of mice for taxonomic studies is almost always limited
in time and restricted in place. The sampling of any species thus
secured is often representative of only one crop and /or niche. Some-
times a few survivors of an older crop, or strays from a different
niche, may be included in the sampling. Such individuals help form
a more nearly exact concept of variation within the species. Occa-
sionally crop and niche variants are mistakenly adjudged distinct
species or perhaps sympatric(!) subspecies.
SOCIABILITY
Most phyllotines are social or gregarious and many are commen-
sal as well. Darwin (in Waterhouse, 1839, p. 44) reported that six
specimens of the type series of Hesperomys bimaculatus (= Calomys
laucha) were discovered in the same burrow. The social and gre-
garious habits of Phyllotis sublimis were observed by Pearson (1951,
p. 147), and Thomas (1900, p. 467) noted that the type and eight
topotypes were dug out of one hole. Because of their preeminently
grazing habits, populations of species of Phyllotis, Andinomys edax,
Chinchillula sahamae and, possibly, Galenomys garleppi, tend to con-
centrate in the midst of localized stands of the more succulent grasses.
In some cases, sociability develops into colonialism through
commensal ism. Small populations of Phyllotis darwini become inte-
grated with colonies of tuco tucos (Ctenomys) or cavies (Cavia, Galea,
and others) by sharing their living quarters and feeding grounds. In-
dividuals of Phyllotis darwini have also been found in the same bur-
rows with Octodon degus, 0. bridgesi, Abrocoma bennetti, Akodon oliva-
ceus, Abrothrix longipilis, Oryzomys longicaudatus, Rattus rattus, and
Marmosa elegans (fide Wolffsohn in Thomas, 1927, p. 556). Pearson
(loc. cit.) noted Phyllotis boliviensis living in a viscacha colony and
P. sublimis sharing homes with nearly every other cricetine of the
same region in the Peruvian altiplano. De la Barrera (1940, p. 572)
records Phyllotis griseoflavus and P. darwini each living together
with Microcavia australis in burrows of the latter in Mendoza,
Argentina.
Sociability in phyllotines is not restricted to natural habitats.
Phyllotis darwini, P. griseoflavus, Calomys laucha and C. callosus are
common tenants of man's habitations, where they compete success-
fully with the introduced commensals Rattus and Mus.
42 FIELDIANA: ZOOLOGY, VOLUME 46
Nothing is known of the habits of the highly localized Piura
desert mouse Phyllotis gerbillus. The ease with which the collector
Celestino Kalinowski secured a series of 17 topotypes suggests, how-
ever, that this species is gregarious, like most of its relatives. On
the other hand, there is nothing in the records of Eligmodontia typus
to indicate that this gerbil-like mouse is anything but solitary out-
side the breeding periods.
RAT AD AS AND PLANT FRUITING CYCLES
Devastations of cultivated fields and store rooms and invasions
of human habitations and villages by inordinately large numbers of
hungry rodents are termed ratadas in most parts of rural South
America. The expression rat plague refers to the same phenomenon
but has been used interchangeably with the differently meaning
bubonic plague. Ratadas are commonplace in South America and a
number of them have been recorded. Only exceptionally were the
rodents involved identified. It is certain, however, that phyllotines,
notably the ubiquitous species of Phyllotis and Calomys, are among
the anonymous "mice" of many ratadas mentioned in the literature.
Ratadas originate in restricted localities when an extraordinary
surplus of natural food, usually the fruit of one or two kinds of plants,
occurs together with ideal cover and nesting sites for mice. In this
environment multiplication of the population of one or a few species
of mice assumes explosive proportions, and the number of individuals
soon exceeds by many times the ordinary carrying capacity of the
range. With termination of the fruiting season and deterioration of
protective cover, the hungry, exposed rodents break out into the
surrounding countryside. By the time a new balance is reached
between the individual and its range, there has been a precipitous
drop in the rodent population and considerable destruction of the
cultivated crops in the overrun area. The many dead mice often
observed after a ratada peak are the victims of exposure, hunger,
thirst, abnormally vicious inter- and intra-specific competition,
cannibalism, and wholesale killing by man and predator. Some-
times disease strikes the rodents with catastrophic effects. Another
cause of high mortality may be the radical change in diet for the
generations of mice that developed chiefly, if not entirely, after
weaning, on one plant food.
In many parts of South America ratadas are correlated with the
fruiting of diverse species of bamboo. One of the earliest recorded
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 43
took place in Valdivia, Chile, in 1780. This ratada is cited by
Philippi and Landbeck (1858, pp. 81-82) from a manuscript written
by the historian and naturalist Claudio Gay. The manuscript adds
that periodic plagues of pericotes (native name for small rodents in
general, and often for Phyllotis darwini and Rattus in particular)
scourged all parts of Chile. The ratadas were known to occur in
cycles of 17 to 20 years that coincided with the cyclic fruiting and
dying of the "coligue," a bamboo used by the Indians for lance
shafts. Philippi and Landbeck (op. cit.) also mention a sudden out-
break of rats in the Araucanian districts of southern Chile, in 1681.
No explanation is given for the ratada and no source for the reference.
However, in 1869 or 1870, Philippi (1879) observed a ratada in
Valdivia, where he was in residence. On that occasion all the
"coligue" bamboos of the province produced seed at the same time
and died immediately thereafter. Philippi noted also that ratadas
occur "sometimes in the south of Chile, Araucania, Valdivia, and
Llanquihue, when the coligue and other species of Bambuseae have
flourished and fructified, an occurrence which happens every 15-20
years." The common native mice that might have participated in
these ratadas are species of Phyllotis, Akodon and Oryzomys nigripes
(= longicaudatus) . According to Schneider (1946, p. 77), Oryzomys
nigripes was probably the species which devastated the fields of Con-
cepcion Province, Chile, during the notorious ratada of July, 1877.
The best account on the subject of the correlation between
ratadas and the fruiting season of certain species of bamboos was
provided by Orville A. Derby (1879, p. 65): "From time to time in
all parts of Brazil the plantations are subject to the depredations of
armies of rats that issue from the forests and consume everything
edible that comes in their way. During a recent excursion in the
province of Parana Mr. Derby found an almost universal lack of
corn throughout the province, due to such invasion of rats, by which
almost the entire crop of last year had been destroyed. This in-
vasion, or plague as it is called, is said to occur at intervals of about
thirty years, and to be simultaneous with the drying of the taquara,
or bamboo, which everywhere abounds in the Brazilian forests. The
popular explanation is that every cane of bamboo sprouts with a
grub, the germ of a rat, within it, and that when the bamboo ripens
and dies the germ becomes a fully-developed rat and comes out to
prey on the plantations. An educated and observant Englishman,
Mr. Herbert H. Mercer, who has resided a number of years in the
province and had an opportunity of studying the phenomenon,
44 FIELDIANA: ZOOLOGY, VOLUME 46
furnished Mr. Derby the following rational and curious explanation :
The bamboo arrives at maturity, flowers and seeds at intervals of
several years, which doubtless vary with the different species. The
period for the species most abundant in Parana is thirty years.
The process, instead of being simultaneous, occupies about five
years, a few of the canes going to seed the first year, an increased
number the second, and so on progressively, till finally the remaining
and larger portion of the canes seed at the same time. Each cane
bears about a peck of edible seed, resembling rice, which is very fat
and nourishing, and is often eaten by the Indians. The quantity
produced is enormous, and large areas are often covered to a depth
of five or six inches. After seeding the cane dies, breaks off at the
root and falls to the ground, the process of decay being hastened by
the borings of larva which live upon the bamboo and appear to be
particularly abundant at seeding time. These larva have doubtless
given rise to the story of the grub developing into a rat. New canes
spring up from the seed, but require seven or eight years to become
fit for use, and thirty to reach maturity. With this sudden and
constantly increasing supply of nourishing food for a period of five
years, the rats and mice, both of native and imported species, in-
crease extraordinarily in numbers. The fecundity of these animals
is well known, and the result after four or five years of an unusual
and constantly increasing supply of excellent food and in the absence
of enemies of equal fecundity, can readily be imagined. The last
of the crop of seed being mature and fallen to the ground, the first
rain causes it to decay in the space of a very few days. The rats,
suddenly deprived of food, commence to migrate, invading the
plantations and houses and consuming everything that does not hap-
pen to be repugnant to the not very fastidious palate of a famishing
rodent. If this happens at the time of corn planting, the seed is
consumed as fast as it can be put into the ground. Mr. Mercer, who
plants annually about fifty acres of corn, replanted six times last
year, and finally gave up in despair. The mandioca is dug up; the
rice crop, if it happens to be newly sown or in seed, is consumed, as is
also everything in the houses in the way of provisions and leather,
if not carefully guarded in tin trunks."
The 30-year blooming cycle of the taquara and its correlation
with ratadas was corroborated by Pereira (1941). The plant was
identified as the taquara lixo (rough bamboo, Merostachys fistulosa
Doell). Pereira also reviewed part of the history of ratadas in
southern Brazil, beginning with a citation of observations made by
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 45
the French botanist, August St. Hilaire, in 1832 (Voyage dans
1'interieur du Bre"sil). Giovannani, Vellozo and Kubiak (1946)
continued the investigation of ratadas in Parand. This time the
outbreak was correlated with the fruiting of the taquara lisa (smooth
bamboo, Merostachys sp.). Here, again, exhaustion of their food
supply in the bamboo groves obliged the mice to erupt into the
neighboring cultivated fields. The species involved in this ratada
included the phyllotine Calomys laucha tener Wagner, and Oryzomys
nigripes Olfers (Oryzomys eliurus Wagner), Holochilus brasiliensis
leucogaster Brandt and Akodon nigrita Lichtenstein (the rato pitoco).
Crespo (1944) studied a ratada of Calomys laucha laucha Olfers
and Akodon benefactus Thomas that developed in fallow fields on the
outskirts of Buenos Aires, Argentina. In this case, prolonged warm
weather and heavy rainfall stimulated superproduction of natural
food and heavy growth of cover favored by the mice. An abrupt
change to abnormally dry, cold weather destroyed forage and cover,
and obliged the rodents to invade adjoining cultivated fields.
A ratada in south coastal Peru was investigated by Gilmore
(1947). Though the affected area lies within the range of Phyllotis
darwini, Gilmore found that only the rata-muca (Oryzomys xanthae-
olus ica Osgood) was involved. The cause for the outbreak was
not determined.
I have found the phyllotine Zygodontomys brevicauda in near
plague numbers in some northern Colombian localities. I also en-
countered other South American rodents, notably the forest dwelling
Oryzomys laticeps and Oryzomys caliginosus, some species of Thoma-
somys, the spiny rat Proechimys guyannensis, and the grassland
Heteromys anomalus and Sigmodon hispidus, in excessive numbers.
The history of ratadas of marsh rats (Holochilus) was recorded else-
where (Hershkovitz, 1955, p. 655).
The meager data in literature, and personal observations in the
field, indicate that fluctuations in populations may be as drastic in
tropical and south temperate latitudes as in Arctic and north tem-
perate ones. Ratadas in the Neotropical region are usually composed
of one, sometimes two, rarely more, species of the local rodent fauna.
Environmental conditions that promote the production of a ratada
of one species may not alter significantly the population of another
species living in the same area. The one or two species least affected
by adverse conditions in a given locality are most likely to become
plagues during optimum conditions. Species able to thrive in newly
invaded territory are also notoriously ratada-prone.
46 FIELDIANA: ZOOLOGY, VOLUME 46
HIBERNATION
Hibernation, or aestivation, as a regular seasonal function, has
not been positively demonstrated in any South American mammal.
There are suggestions, however, that sloths and certain small Patago-
nian marsupials, bats, a marmoset 1 and rodents may become torpid at
irregular intervals. The mouse opossums, Marmosa pusilla (=ele-
gans) and Dromiciops australis, store fat in their bodies, notably at
the base of the tail, in advance of winter and become lethargic during
particularly cold spells. Some phyllotines are also prone to torpidity
when the outside temperature is low. One of the lauchas secured by
Thomas (1916b, p. 184) in Buenos Aires province during the winter
month of June, 1896, is said to have been "dug up, semi-torpid, in
very cold weather, from about 6 inches below the surface of the
ground." The species (described as Hesperomys murillus, a synonym
of Calomys laucha laucha) is not a burrower and Thomas does not
explain its presence underground or state that he himself found it
there. Henry Durnford (in Thomas, 1898a, p. 210) observed that
whereas Phyllotis griseoflavus was excessively numerous and overran
the Colony in Chubut, Argentina, during the summer, it disappeared
in the wintertime. Durnford believed that the animal became dor-
mant. Pearson (1951, p. 147) also puzzled over the sudden disap-
pearance of Phyllotis sublimis Thomas from the Peruvian altiplano
during the rainy season months of October, November and Decem-
ber. However, in regions where the most drastic environmental
change is in rainfall, not temperature, absence of trap or sight records
need not be the result of hibernation. A lush growth of food cover
plants during the rainy season makes mice sedentary, less exposed
to predators and less, if at all, trap prone (see also discussion of
Ratadas, p. 42).
ENEMIES
Phyllotines, together with Akodon (sens, lat.), are the dominant
mammals of the grasslands, scrublands and deserts of South Amer-
ica. As such they are basic food for the carnivores living in the same
range. The most important predators include the weasel (Mustela
frenata), the huron (Grisonella) , species of foxes and wild cats, owls
and hawks. In tropical savannas inhabited by Zygodontomys, snakes
feed largely on small rodents.
1 Callithrix jacchus, in captivity (Kraft, 1957, Saugeth. Mitt., 5: 175).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 47
Precocious development and the short suckling period of young
phyllotines help reduce loss of population to nest-raiding predators.
ECTOPARASITES
The distributional patterns of ectoparasites often provide im-
portant clues to the origin and phylogeny of their mammalian hosts.
Modern parasitologists explore this relationship, and notable contri-
butions on the subject have already been made by many investi-
gators. In addition to those cited below, the works of Hopkins and
Rothschild (1953-56) and Johnson (1957) on fleas (Siphonaptera) may
be consulted to advantage. Ferris and Stojanovich (1951) mono-
graphed sucking lice (Anoplura) and Vanzolini and Guimaraes (1955)
have discussed the geographic distribution and host associations
from a historical point of view.
Few studies have been made of the ecological relationship be-
tween disease-transmitting ectoparasites and Neotropical rodents.
The most outstanding are those of de la Barrera. One of his works
on sylvatic plague and life histories of rodent vectors is cited below;
others are mentioned in the present account of Phyllotis griseoflavus
(pp. 441-461).
A list of some of the fleas, lice, mites, ticks and staphylinid
beetles infesting phyllotines is given herewith. The authorities for
published records are shown in parentheses following the name of the
parasite. Heretofore unpublished records of specimens in Chicago
Natural History Museum are distinguished by the symbol CNHM.
The identifications were made by Dr. Rupert Wenzel, Curator of
Insects of this institution, who also checked the nomenclature of all
parasites listed. An interrogation (?) sign before the name of a para-
site means that the host association is doubtful.
Host names given below are those recognized in the revision.
For concordance between host names originally used by the para-
sitologists cited and those adopted here, see the synonymies and
geographical distributions in the text that follows.
GALOMYS Section
Calomys sorellus Thomas
Tick
Ixodes (Eropalpiger) andinus Kohls (CNHM)
Calomys laucha Olfers
Fleas
48 FIELDIANA: ZOOLOGY, VOLUME 46
Polygenis rimatus Jordan (Costa Lima and Hathaway, 1946)
Craneopsylla minerva wolffhuegeli Rothschild (Hopkins and Rothschild, 1956)
Calomys lepidus lepidus Thomas
Fleas
(l)Plocopsylla pallas Rothschild (Hopkins and Rothschild, 1956)
(l)Tetrapsyllus bleptus Jordan and Rothschild (Traub, 1952)
(l)Neotyphloceras crassispina crassispina (CNHM)
(l)Agastopsylla nylota (CNHM)
C!)Sphinctopsylla inca Rothschild (Hopkins and Rothschild, 1956)
(l)Dysmicus danger Rothschild (Johnson, 1957)
Calomys callosus Rengger
Lice
Hoplopleura hesperomydis Osborn (Hopkins, 1949; Ferris, 1919-35)
Hoplopleura nesoryzomydis Ferris (Hopkins, 1949)
Hoplopleura affinis Burmeister (Ferris, 1919-35)
Flea
Craneopsylla minerva wolffhuegeli Rothschild (Hopkins and Rothschild, 1956)
Calomys callosus expulsus Lund
Flea
Polygenis bohlsi bohlsi Wagner (Costa Lima and Hathaway, 1946)
Zygodontomys lasiurus Lund
Louse
Hoplopleura affinis Burmeister (Hopkins, 1949)
Zygodontomys brevicauda J. A. Allen and Chapman
Louse
Hoplopleura nesoryzomydis Ferris (Hopkins, 1949)
PHYLLOTIS Section
Phyllotis haggardi Thomas
Flea
Nosopsyllus londiniensis Jordan (Johnson, 1957)
Phyllotis andium Thomas
Flea
Craneopsylla minerva minerva Rothschild (CNHM)
Tick
Ixodes (Exopalpiger) andinus Kohls (CNHM)
Beetle
Amblyospinus ancashi Seevers (Seevers, 1955)
Phyllotis darwini posticalis Thomas
Fleas
(l)Plocopsylla pallas Rothschild (Hopkins and Rothschild, 1956)
(t)Dysmicus claviger Rothschild (Johnson, 1957)
Neotyphloceras crassispina crassispina Rothschild (CNHM)
(l)Agaslopsylla nylota Traub (Traub, 1952)
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 49
(l)Tetrapsyllus bleptus Jordan and Rothschild (Traub, 1952)
Cleopsylla townsendi Rothschild (CNHM)
Tick
Ornithodoros sp., larvae (CNHM)
Phyllotis darwini rupestris Gervais
Fleas
Delostichus phyllotis Johnson (Johnson, 1957)
Neotyphloceras crassispina crassispina Rothschild (CNHM; Traub, 1952;
Costa Lima and Hathaway, 1946)
Tetrapsyllus bleptus Jordan and Rothschild (CNHM)
(l)Polygents bytunis Jordan and Rothschild (Costa Lima and Hathaway, 1946)
Plocopsylla inti Johnson (Johnson, 1957)
Sphinctopsylla inca Rothschild (Johnson, 1957)
Louse
Hoplopleitra affinis Burmeister (Hopkins, 1949)
Mite
Euschongastia phylloti Wharton (Wharton, 1948)
Tick
Ornithodoros sp., larvae (CNHM)
Phyllotis darwini darwini Waterhouse
Fleas
Neotyphloceras crassispina chilensis Jordan (Costa Lima and Hathaway, 1946)
Plocopsylla wolffsohni Rothschild (Costa Lima and Hathaway, 1946; Hopkins
and Rothschild, 1956)
Cleopsylla townsendi Rothschild (Johnson, 1957)
Phyllotis darwini xanthopygus Waterhouse
Fleas
Plocopsylla chiris Jordan (Costa Lima and Hathaway, 1946; Hopkins and
Rothschild, 1956)
Plocopsylla achilles Rothschild (Costa Lima and Hathaway, 1946)
Tiamastus subtilis Jordan and Rothschild (Costa Lima and Hathaway, 1946)
Craneopsylla minerva wolffhuegeli Rothschild (Hopkins and Rothschild, 1956)
(l)Polygenis by turns Jordan and Rothschild (Johnson, 1957)
Tiamastus subtilis Jordan and Rothschild (Johnson, 1957)
Phyllolis osilae J. A. Allen
Flea
(l)Polygenis thurmani Johnson (Johnson, 1957)
Phyllotis micropus Waterhouse
Lice
Hoplopleura affinis Burmeister (Hopkins, 1949)
Hoplopleura reducla Ferris (Hopkins, 1949)
Phyllotis boliviensis Waterhouse
Flea
Cleopsylla townsendi Rothschild (Johnson, 1957)
Neotyphloceras crassispina crassispina Rothschild (CNHM)
50 FIELDIANA: ZOOLOGY, VOLUME 46
Louse
Hoplopleura affinis Burmeister (Hopkins, 1949)
Phyllotis sublimis Thomas
Flea
Craneopsylla minerva minerva Rothschild (Johnson, 1957)
Beetle
Amblyopinus sp. (Seevers, 1955)
Phyllotis pictus Thomas
Fleas
(l)Agastopsylla pearsoni Traub (Traub, 1952)
(l)Plocopsylla enderleini Wagner (CNHM)
Cleopsylla townsendi Rothschild (CNHM)
Sphinctopsylla inca Rothschild (CNHM)
Neotyphloceras crassispina crassispina Rothschild (CNHM)
Ectinorus ineptus Johnson (Johnson, 1957)
Louse
Hoplopleura affinis Burmeister (Hopkins, 1949)
Tick
Ixodes sp. nymphs (CNHM)
Phyllotis griseoflavus griseoflacus Waterhouse
Fleas
Craneopsylla minerva wolffhuegeli Rothschild (Costa Lima and Hathaway,
1946; Johnson, 1957)
Dysmicus barrerai Jordan (Costa Lima and Hathaway, 1946)
Dysmicus hapalus Jordan (Costa Lima and Hathaway, 1946)
Hectopsylla stomis Jordan (Costa Lima and Hathaway, 1946)
"Polygenis litargus puelche Del Ponte and Reisel" nomen nudum (Costa Lima
and Hathaway, 1946)
Polygenis occidentalis Cunha (Costa Lima and Hathaway, 1946)
Polygenis platensis cisandinus Jordan (Costa Lima and Hathaway, 1946)
Pulex irritans Linnaeus (Costa Lima and Hathaway, 1946)
Neotyphloceras crassispina hemisus (Jordan, in de la Barrera, 1940)
Louse
Hoplopleura affinis Burmeister (Hopkins, 1949)
Hoplopleura reducta Ferris (Ferris, 1919-35)
Phyllotis amicus Thomas
Fleas
Neotyphloceras crassispina Rothschild (Costa Lima and Hathaway, 1946)
Rhopaplopsyllus cacicus Jordan and Rothschild (Traub, 1952)
Andinomys edax Thomas
Fleas
Dysmicus budini Jordan and Rothschild (Costa Lima and Hathaway, 1946)
Neotyphloceras crassispina hemisus Jordan (Costa Lima and Hathaway, 1946)
(l)Ectinorus disjugis Jordan (Johnson, 1957)
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 51
Chinchillula sahamae Thomas
Fleas
Cleopsylla townsendi Rothschild (Johnson, 1957)
Neotyphloceras crassispina crassispina Rothschild (Traub, 1952)
Tetrapsyllus bleptus Jordan and Rothschild (Traub, 1952)
Plocopsylla enderleini Wagner (CNHM)
C!)Agastopsylla pearsoni Traub (Traub, 1952)
Mite
Euschonygastia phylloti Wharton (Wharton, 1948)
Beetle
Amblyopinus sp. (Seevers, 1955)
Euneomys chinchilloides Waterhouse
Fleas
Barreropsylla excelsa Jordan (Johnson, 1957)
Plocopsylla wolffsohni Rothschild (Johnson, 1957)
Ectinorus onychius onychius Jordan and Rothschild (Johnson, 1957)
Tetrapsyllus rhombus Smit (Johnson, 1957)
SOME SPECIAL EXTERNAL AND CRANIAL
CHARACTERS
Feet
Figure 3
The hind feet of all phyllotines except Pseudoryzomys are small,
generally weak in structure, and adapted primarily for locomotion
on the ground. Most species are good climbers but in none is the
foot obviously specialized for an arboreal habitat.
The hind foot of Pseudoryzomys has evolved into the natatorial
type, characterized by stout proportions, reduction of outer toes,
weak claws, development of interdigital webbing most markedly
between the middle digits the absence of superfluous hair, particu-
larly from the plantar surface of the heel, and obsolescence of the
fifth (outer posterior) postdigital plantar tubercle (fig. 53).
The hind foot of Zygodontomys also departs somewhat from the
usual vole-like phyllotine structure and approaches that of the
palustrine type charactersitic of terrestrial species of Oryzomys. The
foot is stout, fan-shaped, often dark, with relatively thick, long
claws and short, thin, digital bristles.
The most remarkable adaptation is the spade-shaped, gerbil-like
hind foot of Eligmodontia. The form of the extremity and the hairy
cushion of its sole are unique among cricetines. That Eligmodontia
B
D E to
FIG. 3. Plantar surface of left hind foot in dry skin: A, Phyllotis darwini;
B, P. pictus; C, P. gerbillus; D, P. amicus; E, Calomys spp.; F, Eligmodontia
typus; G, Galenomys garleppi.
52
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 53
is a desert jumping mouse is inferred from the structure of its limbs
and knowledge of its habitat.
The hairy heel in phyllotines and a scattering of hairs between
the plantar tubercles in some species are secondary developments,
presumably adaptive, that partially replace the primitive scaly
armor. The extremely hairy sole of Galenomys may be correlated
with the cold climate of its Andean habitat, but sympatric phyllo-
tines are not so benefited. In a like manner the sole of Phyllotis
gerbillus, of the Piura desert, possesses an appreciable covering of
bristles while that of other coastal desert phyllotines is bare.
The fifth hind digit of all species of the genus Phyllotis is suffi-
ciently elongated to be of assistance in climbing. The species of
Calornys are similarly endowed, but their hind foot is extremely
delicate (fig. 38). The hind foot of Andinomys, Chinchillula and
Galenomys is of the ambulatory type common to savanna species, but
nothing definite is known regarding locomotion in these genera.
The hind feet of most phyllotines are remarkably uniform in
structure, but the same types are common to unrelated cricetines
inhabiting savanna or scrub country. The feet of Eligmodontia,
Pseudoryzomys, Zygodontomys, and Galenomys are divergent from
the generalized form but here, too, similar structures have evolved
independently in other murids.
The forefoot of cricetines is smaller and proportionately shorter
than the hind foot, and its first digit is greatly reduced. The pollex
bears a nail in phyllotines and all other cricetines except the special-
ized fossorial forms (Notiomys, Blarinomys, Oxymycterus, Scaptero-
mys] where it is provided with a claw. After locomotion the princi-
pal functions of the forefoot are the seizure and conveyance of food
to the mouth. The forefoot may develop exceptionally long claws
for digging in some non-phyllotines, but it shows no specializations
for a particular mode of locomotion comparable in degree to those
of the hind foot.
Tail
Tail length approximately equal to combined head and body
length is characteristic of the more generalized, terrestrial cricetines.
In a plastic, wide-ranging form like Phyllotis darwini, tail length
varies from about one-third less to two-fifths more than head and
body length. A tail with this variability adapts itself easily to ter-
restrial, fossorial, scansorial, saltatorial and semi-aquatic modes of
life. The specialized tail, whether consistently longer or shorter than
54 FIELDIANA: ZOOLOGY, VOLUME 46
combined head and body length, can easily be derived from the
flexible, medium length, all-purpose type. Tails of vole-like, bur-
rowing Phyllotis sublimis, Calomys lepidus, Galenomys garleppi and
Chinchillula sahamae, are one-third to three-fourths of the head and
body length. Tails of the less specialized Andinomys edax, Phyllotis
micropus, P. boliviensis, P. pictus, Zygodontomys, Calomys laucha,
C. sorellus and C. callosus average between 75 and 100 per cent of
head and body length.
Highly specialized saltatorial rodents may be of the bipodal or
leporid type, with tail very short or vestigial, or they may be of the
tripodal or ricochetal type (cf. Hatt, 1932, pp. 602 et seq.), with tail
stoutly developed and, with rare exceptions, longer than combined
head and body length. No cricetine belongs definitely to either
saltatorial category, but Eligmodontia shows a slight tendency to-
ward the second. The elongated, tufted, balancing type of tail of
scansorial or arboreal rodents is found in Phyllotis griseoflavus and
P. amicus.
In specialized, short-tailed forms, the tail of juvenals is always
proportionately longer to head and body length than in adults. On
the other hand, the tail of young individuals of long-tailed species
is usually proportionately shorter.
Bony Palate
Figure 4
The postdiastemal portion of the hard palate of nearly all crice-
tine species may be classified as short or long and as wide or narrow.
These terms are defined as follows:
Short palate: With median posterior borders of palatines not
extending behind posterior plane of third molars.
Long palate: With median posterior borders of palatines extend-
ing behind posterior plane of third molars.
Wide palate: With distance between inner borders of first molars
greater than length of either molar.
Narrow palate: With distance between inner borders of first
molars less than length of first molar. In many cases the narrow
palate is marked by a pair of deep lateral troughs separated by a
prominent median longitudinal ridge. These features indicate that
the narrow palate derives from a longitudinal corrugation of the
wide palate.
SHORT WIDE
A
If
LONG WIDE
B
Y"
SHORT NARROW
C
LONG NARROW
D
FIG. 4. Hard palates in Muridae: A, short, wide (Thomasomys); B, long,
wide (Phyllotis); C, short, narrow (Neotoma); D, long, narrow (Antinomy*} .
Molars pentalophodont in A, and derivatives of the tetralophodont pattern in B I).
56 FIELDIANA: ZOOLOGY, VOLUME 46
The wide, short, uncomplicated palate such as occurs in Pero-
myscus (s.s.), most species of Thomasomys (fig. 4, A), Rhipidomys
and other related genera, is here regarded as primitive. Brachyo-
dont, bunodont molars, whether pentalophodont or tetralophodont,
are commonly associated with the wide, short, simple palate. On
the other hand, the narrow palate, either long or short, is rarely
associated with the generalized or low crown, crested molars of
cricetines. In a few forms (e.g., Irenomys) the palate has remained
primitively short but is clearly evolving from wide to narrow, while
the molars have already reached an advanced stage of hypsodonty
and lamination. A clearly defined narrow and short palate, however,
does not appear in any South American cricetine. Among North
American peromyscines, the palate of woodrats (Neotoma, Xenomys)
is narrow and short (fig. 4, C) and may become even shorter as it
constricts pari passu with increasing hypsodonty.
The long, postdiastemal portion of the palate evolved from the
short, wide palate by a closing of most of the gap between the median
posterior portions of the paired palatine bones. It represents com-
pletion of the roofing-over process of the secondary or mammalian
palate and is always correlated with complications of the posterior
palatal and postpalatal regions. The evolutionary stages are evident
in living forms. Thus in juvenals with unerupted third molars this
type of palate is still simple and comparatively short. In akodonts
and such peromyscines as Haplomylomys, Podomys, Baiomys, Reithro-
dontomys the palate is wide, with a narrow range of variation from
short to long. Usually, the posterior palatal area in this group is in-
flated, and the pits are roofed (as seen from below) . The wide palate
of the dentally primitive Aporodon also varies from short to barely
long. In phyllotines (fig. 4, B), the postdiastemal portion of the pal-
ate is consistently long and is distinguished by the presence of more
or less conspicuous posterolateral palatal pits or fossae. Here the
palate is wide in all genera except Andinomys and Chinchillula. It is
widest in the brachyodont, bunodont Calomys, Eligmodontia, and
Zygodontomys and becomes progressively narrower with increasing
hypsodonty. The narrow palate in Andinomys (fig. 4, D) and Chin-
chillula is associated with extremely high, flat-crowned molars.
The palate of sigmodonts (Holochilus, Sigmodon, Neotomys,
Reithrodori) is generally wide; the molars, however, are more ad-
vanced than those of phyllotines and the postpalatal pterygoid re-
gion is extremely complicated.
The palate of oryzomyine rodents is definitely long and like the
wide type of most phyllotines. Identical palatal structures in buno-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 57
brachy-pentalophodont oryzomyines and buno-brachy-tetralopho-
dont phyllotines may be independent developments or may point to
a common ancestry.
A primitive palate may be associated with any advanced stage of
evolution in other cranial, dental, and external characters. Con-
versely, a specialized palate may be associated with generalized
characters in other parts of the organism. The structure of the
palate alone, however, tends to be constant or to vary in but one
direction in any given species or genus.
The combination of postdiastemal palatal and molar characters
is an important indicator of generic and supergeneric relationships.
The accompanying diagram (fig. 2) shows the palatal-molar relation-
ship between phyllotines and those cricetine groups with which
comparisons are made.
Proportional length of the diastemal portion of the palate,
whether long or short, is also an important character in the system-
atics of the Muridae, as well as in other rodent groups. However,
among phyllotines and most pastoral cricetines in general, the char-
acter is of little significance. A discussion of its implications, there-
fore, is omitted here. In another section (p. 102) the elongated
type of the diastemal portion of the palate is mentioned in con-
nection with dental specializations and feeding habits.
Supraorbital Region
Figure 23
In most phyllotines, as in Muridae in general, the borders of the
supraorbital region are either divergent or concave mid-frontally.
In some, the sides of the supraorbital region vary from parallel to
concave or divergent. In the concave type, the distance across the
sides of the supraorbital region, measured at the mid-frontal plane,
is always less than the greatest width of the rostrum. In the diver-
gent type, the width across the sides is always more. The primitive
murid supraorbital region was almost certainly of the concave type
but with sides nearly parallel mid-frontally. This condition persists
in many cricetines and in the phyllotine Calomys lepidus, Phyllotix
darwini and others. In Calomys sorellus the sides vary from slightly
concave to parallel mid-frontally, while in Calomys laucha the sides
vary from parallel to slightly divergent.
The supraorbital regions of juvenals of either type is generally
broad without notable constriction or divergence. In adults spe-
58 FIELDIANA: ZOOLOGY, VOLUME 46
cialization of the supraorbital region has led either to further con-
striction of the concave type with formation of longitudinal frontal
ridges or to greater expansion of the divergent type with development
of beading and overhanging frontal ledges. Exaggeration of either
the concave or the divergent type of supraorbital region is also char-
acteristic of old age.
Tendency toward constriction of the supraorbital region is pres-
ent but hardly noteworthy in Phyllotis pictus and P. boliviensis.
In closely related Euneomys chinchilloides, and in sigmodonts like
Reithrodon physodes, Neotomys ebriosus, and Holochilus magnus,
there is marked constriction. Extreme constriction of the supra-
orbital region is attained in microtines.
Increasing expansion of the divergent type of supraorbital region
may be traced in phyllotines from the nearly parallel, square-sided
condition in Calomys laucha to the widely divergent, beaded, ledge-
like supraorbital borders in Calomys callosus, Zygodontomys and
Phyllotis griseoflavus. As in the concave type, development of diver-
gent-sided supraorbitals has not gone far in phyllotines. Most ad-
vanced conditions among other cricetines appear in arboreal forms
such as Tylomys, Ototylomys, Nyctomys and the Oecomys section of
Oryzomys. The correlation between an arboreal habitat and a diver-
gent-sided supraorbital region appears in Old World Muridae as well.
There is no apparent reason for the predominance of the ex-
panded, divergent-sided type of supraorbital region among scan-
sorial and arboreal species of Muridae (including Cricetinae). Also,
no explanation is offered for the greater prevalence of the constricted
concave type of supraorbital region among voles and vole-like mice.
In either case, modification of the supraorbital regions appears to be
of specific rather than generic grade.
Baculum
Figures 5-8
The two basic types of bacula, simple and complex, are defined
and their systematic significance is discussed in a preceding section
(p. 19).
The baculum of all phyllotines of which the element has been
studied is complex (figs. 5, B; 6). This type is characterized by a bony
shaft with an expansion at the base and three soft, cartilaginous or
more or less ossified, digitate processes at the tip. The base (fig. 6)
is marked by a pair of lateral condyles that are thickened or knobby
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 59
in some specimens, undercut or channeled and curled upward in
others. The condyles may be connected along the median line by
an expanse of bone or they may be separated by a median incision.
B
COMPLEX
FIG. 5. Simple and complex types of glandes pene
and bacula. A, glans penis and baculum (dotted) of
Baiomys musculus (after Hooper [1959, pi. 4a]); B,
glans penis and baculum (dotted) of Phyllotis dar-
urini.
The basal contour of the shaft varies from either concave or convex
to nearly plane.
Shafts with the convex base predominate among cricetines with
the complex type of bacula. The same shape of base appears to be
universal among microtines and in cricetines with the simple type
of baculum and glans.
The concave base (figs. 5, 6) is found only in Phyllotis dar-
wini among strictly South American cricetines, and Burt (1960, pi.
24a) figures the baculum of only one North American species, Oryzo-
mys alfaroi, with the same kind of base. The base of the nearly re-
lated Oryzomys melanotus, figured by the same authority (pi. 24e)
is convex.
Bacula of juvenals of phyllotine species with either convex or con-
cave bases, are practically indistinguishable. Evidently, both types
of bases can be derived from the Juvenal of either. All bacula of adult
Phyllotis darwini wolffsohni examined resemble those of the juvenals
of either P. osilae or P. darwini (fig. 7). Of eight bacula of adult
P. darwini caprinus, five are of the Juvenal type as in wolffsohni, the
remaining three are of the usual concave type characteristic of the
baculum of P. darwini. The difference in size between Juvenal and
adult type bacula in adult caprinus is not related to the overall size
of the animals themselves (Table 1).
81270 81274 75438
81282 75543 75380 69155 71257
FIG. 6. Bacula of phyllotines; distal digitate processes not shown.
EXPLANATION OF FIGURE 6
(5 digit numbers are of specimens in Chicago Natural History Museum,
6 digit numbers are of specimens in the Museum of Vertebrate Zoology,
University of California.)
75453 Phyllotis darwini (Huancavelica, Huancavelica, Peru)
115856 osilae (Pairumani, Puno, Peru)
120025 andium (Matucana, Lima, Peru)
23290 " micropus (Rfo Inio, Chiloe Is., Chile)
53166 amicus (Chosica, Lima, Peru)
46123 griseoflavus (Belen, Catamarca, Argentina)
81270 " gerbillus (Piura, Piura, Peru)
81274 " " (Piura, Piura, Peru)
75438 pictus (Tambo, San Miguel, Ayacucho, Peru)
81282 (Quilcayhuanca, Ancash, Peru)
75543 Calomys sorellus (Ocros, Ayacucho, Peru)
75380
71257 Zygodontomys (Muzo, Boyaca, Colombia)
69155 " (Socorre, Cordoba, Colombia)
60
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 61
A parallel relationship in size and shape of bacula exists between
those of Phyllotis osilae osilae and P. osilae phaeus. The baculum of
the first is comparable in size but not in shape to that of adult P. dar-
wini. The single available baculum of an adult P. o. phaeus is Juvenal
in size and, though distinguishable from the baculum of sympatric
specimens of P. darwini, can just as readily be assigned to P. osilae
as to allopatric P. darwini on the basis of its shape (fig. 7).
The size and shape of the baculum in adult phyllotines varies
locally and geographically (fig. 8, Table 1). The smallest baculum
occurs in the large race Phyllotis darwini wolffsohni. The baculum
of the largest race, P. d. magister, is no larger than that of the
smallest race, P. d. rupestris. The difference in size of bacula of the
Camataqui and Tilcara series of P. d. caprinus (fig. 7) is startling.
That of the former is small and agrees with wolffsohni, while that
of the latter is nearly as large as the baculum of rupestris. The
Camargo and Tarija specimens show the same relationship, respec-
tively. This accords with variation noted in the external, cranial
and dental characters of P. d, caprinus.
Presence of thickenings or slightly developed processes on the
mid-shaft region appears to be a local variable in P. darwini. The
processes are present in all seven bacula of P. darwini magister which
were examined and in the two preserved bones of the intergrading
series of P. d. posticalis from Puquio, Peru (fig. 7). Thickenings of
the mid-shaft region occur sporadically in P. d. rupestris but not
in representatives of the populations with which magister is sym-
patric. Three of the four preserved bacula of P. d. posticalis from
Limbani, Peru, are also thickened at mid-shaft but the single bacu-
lum of sympatric P. osilae is not. There is a very slight mid-shaft
thickening in some bacula of caprinus but the shaft appears to be
smooth and evenly tapered in wolffsohni.
There is no relationship between cyclical changes in size of testes
and size of baculum in adult phyllotines.
A correlation between the size and form of the baculum or the
phallus as a whole and the adaptation of the animal to its external
environment is not evident. The penis is designed for the deposition
of sperm in that part of the female genital tract where fertilization
may proceed most effectively. Variations in the form and function
of the female reproductive tract exert selective pressures on the male
reproductive system. The penis that cannot insure delivery of sperm
to egg cannot insure the survival of its kind.
EXPLANATION OF FIGURE 7
(Numbers are of specimens in the Museum of Vertebrate Zoology,
University of California.)
Phyllotis osilae osilae
114702 Pairumani, Puno, Peru
114696
120163 Leon, Jujuy, Argentina
Phyllotis osilae phaeus
116177 Limbani, Puno, Peru
Phyllotis darwini rupestris
114684 Pairumani, Puno, Peru (compare with sympatric P. osilae osilae above)
115887 (compare with P. d. posticalis at right and P. d.
magister below).
Phyllotis darwini posticalis
115809 Puquio, Ayacucho, Peru (compare with P. d. rupestris at left and P. d.
magister below).
120003 Ayacucho, Ayacucho, Peru (compare with P. osilae phaeus above).
116136 Limbani, Puno, Peru (compare with sympatric P. osilae phaeus above).
Phyllotis darwini magister
115874 Tarata, Tacna, Peru
115878 (compare both samples with P. d. rupestris and
P. d. posticalis above).
Phyllotis darwini wolffsohni
120196 Comarapa, Santa Cruz, Bolivia
120194
(compare both samples with P. d. caprinus and P. andium below and
P. o. phaeus above).
Phyllotis darwini caprinus
120204 Tilcara, Jujuy, Argentina
119975 Camargo, Chuquisaca, Bolivia
120208 Tilcara, Jujuy, Bolivia
120201 Tarija, Tarija, Bolivia (compare with P. d. wolffsohni and P. osilae
osilae above).
120132 Camataquf, Tarija, Bolivia.
Phyllotis andium
120034 Surco, Lima, Peru
120037
120025 Matucana, Lima, Peru
(compare all samples with P. osilae above).
62
116177
115887 115809 120003
116136
115874
115878
120196
120194
120204
119975
120208
120201
120132
120034
120037
120025
FIG. 7. Bacula of species and subspecies of the Phyllotis danrini complex;
distal digitate processes not shown. See opposite page for explanation.
63
Chongoyape
Yungay
Ticopampa
FIG. 8.- Bacula of Phyllotis andium showing individual and local variation;
distal digitate processes not shown.
(All
81257
81255
81252
81253
81251
81256
81238
81247
81240
81243
81242
81246
81233
81236
81232
81235
EXPLANATION OF FIGURE 8
bacula in Chicago Natural History Museum. Specimens shown from
left to right are listed in order by their catalog numbers.)
Chongoyape, Lambayeque, Peru
Yungay, Ancash, Peru
Ticopampa (Hacienda Catac), Ancash, Peru
64
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS
65
TABLE 1. Individual and Geographic Variation in Size of Bacula in Phyllotis ssp.
Head
Baculum
width and
Cat. No. Locality length
and
Testes body
length length
Skull
length
Weight
of
animal
Phyllotis danvini limatus
114704
Atico, Arequipa, Peru
30x36
14
121
31
.7
49
114705
Atico, Arequipa, Peru
28x34
6
112
29
.4
38
116677
Atico, Arequipa, Peru
30x39
6
114
29
.3
47
120062
Chosica, Lima, Peru
26x37
11
107
29
.6
Phyllotis darwini posticalis
120086
Casapalca, Lima, Peru
30x39
31
.2
115809
Puquio, 15km. NE.,
29x38
12
134
33
.2
72
Ayacucho, Peru
116024
Puquio, 21 miles ENE.,
30x42
12
128
33
.2
64
Ayacucho, Peru
120003
Ayacucho, Ayacucho, Peru
14x33
4
113
30
.8
114679
Limbani, SmilesSSW.,
30x40
12
127
32
.9
70
Puno, Peru
114680
Limbani, 8 miles SSW.,
31x29
8
131
31
.9
55
Puno, Peru
114683
Limbani, 8 miles SSW.,
32x39
13
125
32,
,8
75
Puno, Peru
116136
Limbani, 4 miles SSW.,
33x35
9
123
30,
2
50
Puno, Peru
Phyllotis darwini magister
115792
RioTorata, 15km. NE.,
19x
8
122
30
.9
Moquegua, Peru
115874
Tarata, 1 km. N., Tacna, Peru
28x41
12
133
33
.4
71
115877
Tarata, 1 km. N., Tacna, Peru
27x42
13
135
34
.5
93
115878
Tarata, 2 km. N., Tacna, Peru
25x35
11
133
31
.6
70
115879
Tarata, 2 km. N., Tacna, Peru
26x38
11
127
32
.8
75
115881
Tarata, 4 km. N., Tacna, Peru
26x39
11
131
32
.9
72
115883
Tarata, 4 km. N., Tacna, Peru
25x43
11
144
34
.5
89
Phyllotis darwini rupestris
115780
Arequipa, 7 km. E. f
26x32
9.5
105
28
.8
40
Arequipa, Peru
115784
Arequipa, 7 km. E.,
21x32
7
88
27
.3
25
Arequipa, Peru
115785
Arequipa, 7 km. E.,
22x31
8
96
27
.2
26
Arequipa, Peru
115786
Arequipa, 12 km. SSW.,
27x36
9
104
29
.2
Arequipa, Peru
115787
Arequipa, 12 km. SSW.,
23x36
10
102
29
.2
Arequipa, Peru
116124
Arequipa, 52 miles ENE.,
28x37
110
29
.5
48
Arequipa, Peru
66
FIELDIANA: ZOOLOGY, VOLUME 46
TABLE 1. Individual and Geographic Variation in Size of Bacula
in Phyllotis ssp. (continued)
Cat. No. Locality
116126 Huaylarco, Arequipa, Peru
116127 Imata, Arequipa, Peru
116128 Salinas, Arequipa, Peru
114684 Pairumani, Puno, Peru
115887 Pairumani, Puno, Peru
1 14685 Santa Rosa, Puno, Peru
1 14686 Santa Rosa, Puno, Peru
115816 Have, Puno, Peru
115817 Have, Puno, Peru
115819 Juli, Puno, Peru
115822 Pampa de Ancomarca,
Puno, Peru
115823 Pampa de Ancomarca,
Puno, Peru
115825 Puno, 5 km. W., Puno, Peru
1 1 5888 Puno, 5 km. W., Puno, Peru
1 1 5827 Puno, 82 km. W., Puno, Peru
115891 Puno, 15 km. W., Puno, Peru
1 1 5830 Rio Santa Rosa, Puno, Peru
115831 Rio Santa Rosa, Puno, Peru
1 1 5870 Pomata, Puno, Peru
116130 Asillo, Puno, Peru
116134 Tincopalca, Puno, Peru
1 1 6690 Juliaca, Puno, Peru
115799 Torata, 10 km. NE M
Moquegua, Peru
115812 Lago Suche, Moquegua, Peru
115832 Tarata, 4 km. N., Tacna, Peru
115837 Tarata, 4.5 km. N., Tacna, Peru
115838 Tarata, 4.5km. N., Tacna, Peru
1 1 5840 Tarata, 2 km. N., Tacna, Peru
115843 Tarata, 2 km. N., Tacna, Peru
115845 Tarata, 3 km. N., Tacna, Peru
115846 Tarata, 4 km. N., Tacna, Peru
115847 Tarata, 5 km. N., Tacna, Peru
1 1 5849 Tarata, 20 km. N., Tacna, Peru
115853 Tarata, 20 km. N., Tacna, Peru
1 1 6788 Tarata, 8 miles NE., Tacna, Peru
1 1 6792 Caritaya, Tarapaca, Chile
1 1 6782 Caritaya, Tarapaca, Chile
1 1 6783 Caritaya, Tarapaca, Chile
1 1 6784 Caritaya, Tarapaca, Chile
1 1 6778 Toconce, Antof agasta, Chile
1 1 6780 Toconce, Antof agasta, Chile
Baculum
width and
length
Head
and
Testes body
length length
Skull
length
Weight
of
animal
29x39
11
129
32.0
67
26x36
12
120
30.3
50
29x41
119
49
34x42
14
118
32.0
62
31x40
13
121
31.1
63
30x38
10
120
31.0
56
25x34
12
105
29.3
44
28x40
12
114
30.7
54
34x39
12
107
31.4
53
16x30
5
92
27.1
31
26x32
11
110
28.5
46
28x36
11
127
31.0
69
27x38
12
118
31.2
60
25x29
10
109
28.8
42
21x35
11.5
103
28.0
38
30x42
126
32.8
68
30x39
11
133
31.7
19x35
10
108
30.0
27x40
11
119
31.2
64
27x38
11
118
30.2
46
x38
11
124
31.7
34x41
11
123
31.0
55
25x36
9
97
28.5
40
26x34
11
111
31.7
61
28x36
11
123
31.6
n 25x34
9.5
94
26.8
32
i 28x41
11
116
30.1
58
26x37
10
103
28.6
39
26x
8
99
27.7
35
28x38
9
101
30.0
39
27x37
10
113
29.5
52
x32
94
28.2
32
i 25x36
12
112
30.4
56
i 26x35
10
111
31.5
52
i 29x37
9x6
116
29.9
51
29x38
110
29.9
43
26x37
10
114
29.1
50
28x32
10
104
42
x36
10
117
52
30x37
8
113
29.5
50
31x37
118
28.3
43
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS
67
TABLE 1. Individual and Geographic Variation in Size of Bacula
in Phyllotis ssp. (continued)
Head
Cat. No.
Baculum
and
Weight
width and Testes
body
Skull
of
Locality length length
length
length
animal
Phyllotis dancini wolffsohni
Tapacari, Cochabamba, Bolivia 13 x 33 6
135
31.8
57
Tapacari, Cochabamba, Bolivia 10 x 28 4
103
28.1
Tapacari, Cochabamba, Bolivia 10x27 4
117
30.8
52
Punata, 8 miles NE., 10x29 4
114
29.0
49
Cochabamba, Bolivia
Punata, 10 miles NE., 8x27 4
112
29.4
42
Cochabamba, Bolivia
Comarapa, Santa Cruz, Bolivia 14x33 5
129
31.0
55
Comarapa, Santa Cruz, Bolivia 7x25 6
116
30.5
52
Phyllotis danrini capritms
Tilcara, Jujuy, Argentina 24 x 37 10
116
30.4
Tilcara, Jujuy, Argentina 28x40 11
116
31.1
Tilcara, Jujuy, Argentina 26x38 11
123
32.2
Tilcara, Jujuy, Argentina 15x31 7
114
29.7
Camargo, Chuquisaca, Bolivia 26 x 38 7
122
30.7
47
Camataqui, Tarija, Bolivia 17x32 7
118
31.4
56
Camataqui, Tarija, Bolivia 1 1 x 23 4
116
28.1
35
Camataqui, Tarija, Bolivia 12x23 4
101
29.0
39
Tarija, Tarija, Bolivia 13x32 5
126
31.7
Phyllotis osilae osilae
Calacala, Puno, Peru 29x42 10
118
51
Calacala, Puno, Peru 33x44 10
125
28.2
55
Calacala, Puno, Peru 29 x 39 12
124
30.8
53
Calacala, Puno, Peru 29 x 43 7
124
30.8
55
Pairumani, Puno, Peru 28x43 12
131
32.0
69
Pairumani, Puno, Peru 24 x 38 9
105
27.6
32
Pairumani, Puno, Peru 32x42 10
129
31.5
57
Pairumani, Puno, Peru 29 x 43 11
124
31.9
66
Pairumani, Puno, Peru 30x43 11
119
31.0
58
Juli, Puno, Peru 27x38 10
122
31.4
70
Puno, 15km. W., Puno, Peru 26x37 12
120
30 . 7
51
Puno, 5km. W., Puno, Peru 30x37 10
116
31.3
52
Pomata, Puno, Peru 25 x 10
126
32.0
69
Pomata, Puno, Peru 25 x 42 9.5
121
31.0
56
Pomata, Puno, Peru 23x36 8
122
29.8
60
Pomata, Puno, Peru 22x41 7
115
30.9
52
Pomata, Puno, Peru 28 x 9
127
31.1
62
Pomata, Puno, Peru 23x38 8
118
30.6
47
Asilla, Puno, Peru 24 x 40 7
115
30 . 4
68
FIELDIANA: ZOOLOGY, VOLUME 46
TABLE 1. Individual and Geographic Variation in Size of Bacula
in PhyUotis ssp. (continued)
Cat. No. Locality
1 1 6686 Arapa, Puno, Peru
120163 Leon, Jujuy, Argentina
116177 Limbani, Puno, Peru
Head
Baculum and Weight
width and Testes body Skull of
length length length length animal
23x36 4 112 30.3 46
11x31 4 109 29.0
19x32 6 126 31.5 54
PhyUotis
120008 Canta, Lima, Peru
120017 Huaros, Lima, Peru
120022 Matucana, Lima, Peru
1 20023 Matucana, Lima, Peru
120024 Matucana, Lima, Peru
120025 Matucana, Lima, Peru
120034 Surco, Lima, Peru
120035 Surco, Lima, Peru
120037 Villavista, Lima, Peru
81232 Hacienda Catac, Ticopampa,
Ancash, Peru
81233 Hacienda Catac, Ticopampa,
Ancash, Peru
81235 Hacienda Catac, Ticopampa,
Ancash, Peru
81236 Hacienda Catac, Ticopampa,
Ancash, Peru
81238 Yungay, Ancash, Peru
81240 Yungay, Ancash, Peru
81247 Yungay, Ancash, Peru
81243 Yungay, Ancash, Peru
81246 Yungay, Ancash, Peru
81242 Yungay, Ancash, Peru
81251 Chongoyape, Lambayeque, Peru
81252 Chongoyape, Lambayeque, Peru
81253 Chongoyape, Lambayeque, Peru
81255 Chongoyape, Lambayeque, Peru
81256 Chongoyape, Lambayeque, Peru
81257 Chongoyape, Lambayeque, Peru
andium
14x29
100
27.5
14x29
103
28.8
14x31
106
28.0
11x23
95
26.6
16x31
103
27.8
16x30
111
29.3
9x25
99
28.4
14x30
105
28.4
17x29
116
30.5
14 x-
123
29.3
14x
111
27.7
14 x
109
27.8
14x
110
27.3
17x29
119
30.2
15x25
97
27.5
13x
113
28.2
12x24
112
26.6
15x27
117
28.3
14x
117
28.5
13x
99
26.4
17x
99
26.7
14x26
95
25.0
15x27
103
25.7
20 x
114
27.6
17x29
108
27.2
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 69
DENTAL CHARACTERS AND EVOLUTION
Enamel Folds in Rodent Molar Evolution
The crown pattern of the molars of cricetines and many other
rodents can be most accurately described in terms of the enamel folds.
A name for each definable fold is as necessary a tool in the study of
rodent phylogeny as a name for a primary cusp or loph. The fold
terminology used here was proposed by me in 1944 (p. 14). Another
very useful terminology based on beaver molars was devised by
Stirton (1935, p. 392). However, the definitions of the folds as
originally presented by these authors lack the precision and scope
needed for present purposes. Enamel folds are now defined as
fundamental dental features. It follows that all folds developed in
the same way in the same place are homologous.
The letter symbols used in the following definitions are also
shown in figure 9.
Major fold (MF) : Based on posterior enamel wall, or ridge, of
protocone(-id) and, except where enteroloph or ectolophid is well
developed, continuous with anterior enamel ridge of the hypocone
(-id). The major fold is the most convenient base reference for
orientation and homologization of all quadritubercular molar ele-
ments.
First minor fold (NF 1): Based on posterior enamel ridge of
anteroconule(-id) and continuous with anterior border of proto-
cone(-id); non-existent in absence of anteroconule(-id).
Second minor fold (NF 2) : Based on anterior enamel ridge of
posteroconule(-id) and continuous with posterior border of hypo-
cone(-id); present in a few cricetines (e.g., Punomys; third upper
molar of Neotomys), in some murines and in many caviomorphs.
First primary fold (PF 1) : Of upper molar, based on anterior
enamel ridge of paracone and continuous with posterior border of
anteroloph; may be obsolete or absent in molar with reduced or
excessively worn procingulum. Of lower molar, based on posterior
enamel ridge of metaconid and continuous with anterior ridge of
either entoconid, or, if present, mesolophid.
Second primary fold (PF 2) : First fold of tribosphenic, or primitive
therian upper molar (Simpson, 1936), and most persistent through
attrition and specialization; based on anterior ridge of metacone and
continuous with posterior ridge of either paracone or, if present,
mesoloph. Of lower molar, based on posterior ridge of entoconid
and continuous with anterior ridge of posterolophid.
EXPLANATION OF FIGURE 9
MF major fold
NF 1 first minor fold
NF 2 second minor fold
PF 1 first primary fold
PF 2 second primary fold
SF 1 first secondary fold
SF 2 second secondary fold
IF 1 first internal fold
IF 2 second internal fold
NAMES OF FOLDS
AIF
AMF
ASF
ALF
ABF
APF
anterior internal fold
anterior median fold
anterior secondary fold
(upper molars only)
anterior lingual fold
(upper molars only)
anterior labial fold
(lower molars only)
anterior primary fold
(lower molars only)
NAMES OF CUSPS
Upper Molars (A)
1. Protocone
2. Hypocone
3. Paracone
4. Metacone
5. Mesoloph 1
6. Mesostyle /
7. Anteroloph
8. Anterolabial style
9. Anteroconule
10. Anterolingual style
11. Anterolabial conule
12. Anterolingual conule
13. Anteromedian style
14. Posteroloph
15. Posterostyle
16. Posteroconule
17. Enteroloph
18. Enterostyle
19. Paralophule
20. Metalophule
a. Antero-median protolophule
b. Postero-median
c. Antero-median hypolophule
d. Postero-median "
mesolophostyle (-id)
Procingulum
Postcingulum
Lower Molars (B)
1. Protoconid
2. Hypoconid
3. Metaconid
4. Entoconid
5. Mesolophid
6. Mesostylid
7. Anterolophid
8. Anterolingual stylid
9. Anteroconulid
10. Anterolabial stylid
11. Anterolingual conulid
12. Anterolabial conulid
13. Anteromedian stylid
14. Posterolophid
15. Posterostylid
16. Posteroconulid
17. Ectolophid
18. Ectostylid
19. Metalophulid
20. Entolophulid
a. Antero-median protolophulid
b. Postero-median
c. Antero-median hypolophulid
d. Postero-median "
70
LABIAL
LINGUAL
(3) M F
UPPER RIGHT MOLARS
LOWER LEFT MOLARS
FIG. 9. Master plan of the occlusal surface of rodent molars showing all
elements present in the enamel pattern of Muridae. Supernumerary lophules
(-ids) present in the third molars of some forms (cf. Otomyx, fig. 16, A) are not
shown. For key to numbers and abbreviations see opposite page.
71
72 FIELDIANA: ZOOLOGY, VOLUME 46
First secondary fold (SF 1) : Of upper molar, based on anterior
enamel ridge of mesoloph ; sometimes divided into lateral and median
portions by a paralophule; non-existent in absence of mesoloph. Of
lower molar, based on posterior enamel ridge of anterolophid ; non-
existent in absence of anterolophid.
Second secondary fold (SF 2) : Of upper molar, based on anterior
border of posteroloph and continuous with posterior enamel ridge of
metacone; non-existent in absence of posteroloph. Of lower molar,
based on posterior enamel ridge of mesolophid; sometimes divided
into lateral and median portions by an entolophulid ; non-existent in
absence of mesolophid.
First internal fold (IF 1): Enamel island defined by internal
enamel ridges or lophules(-ids) connecting protocone(-id) with
paracone (or metaconid); may be coalesced with first primary or
first secondary fold.
Second internal fold (IF 2) : Enamel island defined by internal
enamel ridges or lophules(-ids) connecting hypocone(-id) with meta-
cone (or entoconid); may be coalesced with second primary or
second secondary fold.
In rodents with premolars absent, the procingulum of the first
molar is hypertrophied and plicated. The resultant lophs and con-
ules duplicate in appearance the structures immediately behind and
partially replace the functions of the premolar lost in front. The
folds defining the components of the procingulum are defined as
follows:
Anterior median fold (AMF) : Loop defining internal borders of
anterolingual and anterolabial conules(-ids) ; may be weakly defined
in the specialized molar or isolated and coalesced with anterior in-
ternal fold defined below.
Anterior secondary fold (ASF) : Defines opposing enamel walls of
anterolabial conule and anteroloph.
Anterior lingual fold (ALF) : Defines opposing enamel walls of
anterolingual conule and anteroconule.
Anterior primary fold (APF) : Defines opposing enamel walls of
anterolingual conulid and anterolophid.
Anterior labial fold (ABF): Defines opposing enamel walls of
anteroconulid and anterolabial conulid.
Anterior internal fold (AIF) : Enamel island defined by internal
enamel ridges or lophules(-ids) connecting anterolingual and antero-
labial conules(-ids); not to be confused with secondarily isolated
anterior folds with which it may be coalesced.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 73
Supernumerary folds: In some rodents, for example, Otomys (fig.
16, A), there is a tendency for the development of supernumerary
crests posteriad to the posteroloph(-id) or posteroconule(-id) of the
third molar. The folds defining these conules are treated as super-
numerary secondary folds (SF 3, SF 4, etc.) or supernumerary minor
folds (NFS, NF4, etc.).
Summary. Folds based on the main cusps of the primitive
therian molars are the major and the two primary folds. The minor
and secondary folds are based on lophs and other secondarily de-
veloped dental elements. Folds based on homologous cusps and
lophs are correspondingly homologous. Folds based on derivatives
of the anterior cingulum of the first molar and of the posterior cingu-
lum of the third molar are analogous or, rather, homoplastic struc-
tures. Simple accessory styles are not defined by folds, even when
originating from or secondarily fused with, elements identified
with folds.
The first fold to characterize the tribosphenic upper molar is the
second primary (PF 2). The major fold (MF) is the second to appear
in phylogeny. This fold delimits the hypocone and marks the
quadritubercular upper molar. The first fold of the tribosphenic
lower molar was one between paraconid and metaconid. In therians,
such as rodents that have lost the paraconid, the first primary (PF1)
and the major fold (MF) are the oldest. In the upper molar, the
first primary and the two secondary folds delimit the lophs already
present in the earliest cricetine molars. Internal and median folds
appear last and are secondary modifications developed within the
cricetine line. Minor folds inaugurate the cycle of specialization.
The second minor fold, especially, is a development of the grazing
type of molar in several rodent lines.
In lower molars major and minor folds may be regarded as equiva-
lents of corresponding folds of the upper molars. Primary and
secondary folds, on the other hand, are not equivalents of the same
named folds of the upper molars. The same terminology is used,
nevertheless, for convenience.
Once the maximum number of folds have become established in a
species, their order of isolation and disappearance, whether through
attrition in the individual or specialization in the line of descent,
is the inverse of their order of appearance in phylogeny. Thus, the
second primary fold, the first fold to define the tribosphenic upper
molar, is the last to disappear.
74 FIELDIANA: ZOOLOGY, VOLUME 46
Procingulum and Postcingulum
Homologies of the primary cusps and lophs of cricetine cheek
teeth defined by Wood and Wilson (1936) have been generally ac-
cepted. However, attempts to apply extensively the Wood and
Wilson definitions for derivatives of the cingulum meet with diffi-
culties.
The cingulum of the quadritubercular molar in rodents is dis-
continuous. The anterior and posterior portions are most de-
veloped, and, in the more generalized tooth, they give rise to tubercles
similar in form and structure to primary cusps and lophs. Lateral
portions of the cingulum may appear in the form of well-defined
ledge-like outgrowths supporting one or more stylar processes. These
processes, however, may be present with only the merest trace of
their original lateral cingular base.
The terms anterior cingulum and posterior cingulum have been
applied not only to these basic portions of the cingulum but have
been used at times for elements secondarily derived from the cingula.
To avoid ambiguity, the terms procingulum and postcingulum, pro-
posed by me in 1955 (p. 651), are reintroduced for the complex
derived from the anterior cingulum and the complex derived from
the posterior cingulum, respectively. These terms are particularly
useful in the analysis of murid molars. They are defined as follows:
Procingulum, upper molars: Anterior cingulum with the follow-
ing complex of functional elements derived from it:
(a) Anteroloph (fig. 9, A 7): Anteroloph of Wood and Wilson
("anterior cingulum" of some authors).
(b) Anterolabial style (fig. 9, A 8) : When present usually fused
with anteroloph; if not discrete, its presence indicated when
combined elements extend to lateral margin of tooth.
(c) Anteroconule (fig. 9, A 9): Small anterior cone defined by
first minor fold.
(d) Anterolingual style (fig. 9, A 10) : When present never well
developed and generally juxtaposed against anteroconule.
(e) Anterolabial conule (fig. 9, A 11) : Always present in first
molar with well-developed procingulum; absent as discrete
element in second and third molars.
(f) Anterolingual conule (fig. 9, A 12) : Like preceding, always
present in first molar with well-developed procingulum;
absent in second and third molars.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 75
Note: Anterolabial and anterolingual conules may have been
originally independent and discrete derivatives of the anterior cingu-
lum, and the two may subsequently have fused into a single cone,
the anterocone of Wood and Wilson. The possibility, however, that
a simple anterocone is the primitive structure in rodents cannot
be discounted.
Anteromedian style (fig. 9, A 13) : When present arising from
anteromedian border of anterior cingulum; rarely well de-
*T*"il rf"Vt"Vrf-Wl
(g)
veloped.
Postcingulum, upper molars: Posterior portion of cingulum with
the following complex of functional elements derived from it:
(a) Posteroloph (fig. 9, A 14) : Posteroloph of Wood and Wilson
("posterior cingulum" of some authors).
(b) Posterostyle (fig. 9, A 15) : When present usually fused with
posteroloph; if not discrete, presence indicated when com-
bined elements extend to lateral margin of tooth.
(c) Posteroconule (fig. 9, A 16): Lateral posterior cone defined
by second minor fold; analogous to anteroconule in origin.
(d) Supernumerary crests: See definition below (p. 76).
Procingulum, lower molars:
(a) Anterolophid (fig. 9, B 7): Less developed than anteroloph.
(b) Anterolingual stylid (fig. 9, B 8): Usually absent; when
present less developed than corresponding element (antero-
labial style) of upper molar.
(c) Anteroconulid (fig. 9, B 9): Frequently present when cor-
responding element (anteroconule) of upper molar is absent.
(d) Anterolabial stylid (fig. 9, B 10): Generally present in juxta-
position with anteroconulid and more developed than cor-
responding element (anterolingual style) of upper molar.
(e) Anterolingual conulid (fig. 9, B 11).
(f) Anterolabial conulid (fig. 9, B 12).
Note: Anterolingual and anterolabial conulids together compose
the anteroconid of Wood and Wilson.
(g) Anteromedian stylid (fig. 9, B 13): Arising from anterior
border of cingulum ; rarely present.
76 FIELDIANA: ZOOLOGY, VOLUME 46
Postcingulum, lower molars:
(a) Poster olophid (fig. 9, B 14), and poster ostylid (fig. 9, B 15):
When present, generally better developed than correspond-
ing elements of upper molar. The posteroconulid (fig. 9,
B 16) may be present or absent irrespective of presence of
posteroconule.
(b) Supernumerary crests: See definition below.
Supernumerary crests, upper and lower molars:
A crest, or series of crests, in the form of cuspules, lophs or
laminas, may develop posteriad to the posteroloph(-id) or
posteroconule (-id) of the third molar. Such supernumerary
structures are absent in cricetines and murines but are
present in otomyines (fig. 16, A), microtines and gymnuro-
myines (fig. 16, D). They are here classified as postero-
supernumerary crests, lophs, or laminas. The folds defining
them are a continuation of the numerical sequence of
secondary folds and minor folds (see p. 73).
The Mesoloph in the Pentalophodont and
Tetralophodont Patterns
Figure 10
The complex, or pentalophodont, cricetine molar is characterized
by five primary transverse crests. Those of the upper molar are
defined by I, procingulum; II, paracone; III, mesoloph fused with
mesostyle; IV, metacone; V, postcingulum. The primary transverse
crests of the lower molar are defined by I, procingulum; II, meta-
conid: III, mesolophid fused with mesostylid; IV, entoconid; V,
postcingulum. The procingulum and postcingulum are described
(see p. 74). All molars of oryzomyine, thomasomyine and some
peromyscine rodents (see footnotes 1-3, p. 84) are pentalophodont.
The secondarily simplified, or tetralophodont, cricetine molar is
marked by the same primary transverse crests that characterize the
complex molar except that crest III, the fused mesoloph-mesostyle
(-id) complex is disjunct, incomplete or absent. Derivatives of the
tetralophodont molars are the trilophodont molar, with crest III and
either crest I (procingulum) or crest V (postcingulum) obsolete or
indefinable; the bilophodont molar, with crests I, III, and V obsolete
or indefinable; and the cylindriform molar, with only crest II cer-
77
78 FIELDIANA: ZOOLOGY, VOLUME 46
tainly definable. No sharp line can be drawn between the tetralo-
phodont and derivative patterns. As a rule, even the cylindriform
molar in the uneroded state retains signs of the erstwhile discreteness
of one or more of crests I, IV, and V. Cricetines with basic tetralo-
phodont patterns are all the New and Old World species except those
of the groups mentioned in the preceding paragraph.
There is considerable variation in the degree of disjunction, re-
duction, or obsolescence, of crest III, in certain cricetines of the
tetralophodont groups. Here, mesoloph(-id) and mesostyle(-id) are
independent of each other. Either element may be present in the
absence of the other, or both may be present in some molars and
absent in others of the same specimen. In no case are mesoloph
(-id) and mestostyle(-id) simultaneously present in all upper and
lower molars. Hooper (1952, pp. 177-183) attempted to show that
the dental pattern of the tetralophodont group, represented by
Reithrodontomys (s.s.), graded into that of the pentalophodont group,
represented by Aporodon. His observations were based on 2486
specimens of all species of the genera concerned. Hooper analyzed
only the first and second upper molars and made no distinction be-
tween independent mesoloph and mesostyle and the same elements
fused as a single functional element, the mesolophostyle. Examina-
tion of the same species in the collections of Chicago Natural History
Museum and the University of Michigan Museum of Zoology reveals
that in Aporodon a fused mesoloph-mesostyle is present in all upper
molars and a fused mesolophid-mesostylid is present in all lower
molars. On the other hand, in no species of Reithrodontomys (s.s.)
are there either fused or independent mesoloph and mesostyle in the
third upper molar, and in no species are there fused or independent
mesolophid and mesostylid in any of the lower molars (fig. 11). In
worn first and second upper molars of some specimens of Reithro-
dontomys, the crown surfaces of mesoloph and mesostyle may be
abraded to the same level and appear to be a single continuous
mesoloph-mesostyle. The unworn molars in the same species, how-
ever, reveal the mesoloph and mesostyle as truly discrete elements.
The evidence presented here, and, inadvertently, by Hooper
(see fig. 11) shows no intergradation in dental characters between
Aporodon and Reithrodontomys. The discrepancy seems to be slight
but is highly significant in a group of intimately related forms where
differences are more often relative than absolute, and where parallel
development of similar but independently acquired characters is
commonplace.
mis
ml
ms
L msd
msd
FIG. 11. A, B, right upper and left lower molars of Aporodon tenniroslris,
showing well-developed mesoloph-mesostyle(-id) (mis); C, D, right upper and
left lower molars of Reithrodontomys fulvescens with mesoloph (ml) obsolescent,
mesolophid absent, and independent mesostyle (ms) and mesostylid (msd) present.
Note the advanced stages of lamination in m a and sigmation in m s . (After
Hooper, 1952, figures 4C, D, 5C, D.)
79
,1-msd
80 FIELD IANA: ZOOLOGY, VOLUME 46
The mesoloph(-id) arose in some groups of Rodentia before crice-
tines were defined. The mesostyle antedates the Rodentia. It is
moot whether the ancestral cricetine molar was characterized by an
independent mesoloph(-id) and mesostyle (-id) or by the fusion of
the two elements. Either arrangement could have arisen indepen-
dently and either could develop from the other. It is significant,
however, that in living New World cricetines the fused mesoloph-
mesostyle(-id) occurs only in the more generalized molars. With spe-
cialization, mesoloph(-id) and mesostyle (-id) degenerate, lose their
triturative function and become obsolete or disappear altogether
in hypsodont, laminate, triangulate and all other advanced types of
cricetine molars. On the other hand, some Old World murids, such
as the Malagasy Gymnuromys (fig. 16, D), have retained the fused
mesoloph-mesostyle(-id) through the processes described below
(pp. 86-93) as planation, hypsodonty and advancing lamination.
In another phyletic line, represented by Neocometes Schaub and
Zapke (fig. 16, C) of the European Miocene, the fused mesoloph-
mesostyle(-id) persisted through stages of planation and lamination.
The "Pseudomesoloph" and the Dental Pattern
in Cricetine Systematics
In some cricetines a "pseud omesoloph (-id)" (fig. 12) appears in
one or more molars, most commonly the first or second upper and
the first lower. This false "mesoloph" is the paralophule (fig. 9), an
enamel extrusion of the posterior border of the paracone. The false
"mesolophid" is the entolophulid (fig. 9), which originates from the
anterior border of the entoconid. In contrast, the true mesoloph (-id)
is derived from the longitudinal enamel ridge (the mure, or Langs-
grat) connecting protocone with hypocone (protoconid with hypo-
conid). In many species lophule(-id) and mesoloph (id) are present
in the same tooth as discrete elements. In cricetines such as the
phyllotine Zygodontomys, without mesoloph (-id), the "pseudomeso-
loph," i.e., the paralophule, is sometimes well developed. Its link-
age with the mesostyle adds to its simulation of the true mesoloph.
Hoffmeister (1951, p. 14, fig. 7) described and figured a "pseudo-
mesolophid" (i.e., entolophulid) in m T of Peromyscus truei Shufeldt.
Although he labeled and treated the element as a "mesolophid,"
Hoffmeister clearly distinguished (in text) this structure from the
true mesoloph present in the upper molars of the same animal.
Some time after the manuscript of this paper was completed and
submitted for publication, Hooper's (1957) remarkably detailed
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 81
study of the accessory elements of the molars of the cricetine genus
Peromyscus (sensu lato) came to hand. Unfortunately this work
fails to distinguish paralophule and entolophulid from mesoloph and
mesolophid, respectively. Thus, some of the 8 diagrams presented
by Hooper (op. cit., fig. 1, p. 9) to show the relationship between
mesostylid
entolophulid
("pseudomesolophid")
FIG. 12. Left lower first molar of Peromyscus
truei gilberti (after Hoffmeister, 1951, p. 14, fig. 7).
The mure (or Langsgrat) is the median longitudinal
enamel ridge connecting metaconid with entoconid.
The true mesolophid (absent) is a diverticulum of
the mure. The "pseudomesolophid" is the ento-
lophulid, a ridge protruding from the entoconid.
(For names of all parts of the tooth see fig. 9,
p. 71.)
what are termed mesoloph (-id) and mesostyle(-id), require other in-
terpretations. The first diagram (with caption " + ") shows meso-
style(-id) free, as described. On the other hand, the succeeding
diagrams, labeled 1 to 5 inclusive, show mesostyle and mesostylid
fused with paralophule and entolophulid, respectively, not mesoloph
or mesolophid, as implied in the caption and text. The ridge with
which the mesostyle (-id) is coalesced in diagram 6 may be the true
mesoloph (-id). The correct identification of that element can be
determined only in the real tooth. The transverse ridge in diagram 7
is rightly identified as the mesoloph (-id) fused with the mesostyle(-id).
Bader (1959, p. 600) used Hooper's system for a statistical
analysis of the dental traits in three species of Florida Peromyscus.
Although he recognized that the true mesoloph (-id) and pseudo-
mesoloph(-id) are not homologous, Bader treated them as one
in computing their percentage of penetrance in each of the first
two upper and lower molars.
Misidentification or confusion of paralophule and entolophulid
with mesoloph and mesolophid, respectively, may lead to a miscon-
struction of the roles played by each of these elements in the evolu-
tionary process. Paralophule and entolophulid are specializations
that evolve after the mesoloph and mesolophid have become estab-
82 FIELDIANA: ZOOLOGY, VOLUME 46
lished. They may also originate while the mesoloph and mesolophid
are becoming obsolete or have disappeared altogether. In the first
instance, paralophule and entolophulid behave as accessories of the
mesoloph and mesolophid, respectively. In the second instance, they
act as functional replacements, i.e., as "pseudomesoloph" and "pseu-
domesolophid," respectively.
The metalophule and metalophulid (fig. 9) are analogous elements
that may also be confused with the mesoloph and mesolophid, respec-
tively. They are of infrequent occurrence and of no concern in the
present discussion.
Regardless of the identifications made or the terminologies used,
Hooper's statistical analyses, figures and graphs clearly reveal the
precise styles (-ids), lophs (-ids), and lophules(-ids) involved in the
enamel pattern of each of the 17 species of Peromyscus studied. The
accumulated data prove that in all populations of some species of
Peromyscus molar patterns are essentially stable. In other species,
the patterns are geographically variable. Where such variability
exists, Hooper (op. cit., p. 48) points out that "populations that
inhabit arid situations . . . have simpler teeth, with fewer and smaller
styles and lophs, than populations of the same species that live in
denser cover in more humid areas. This is in harmony with a cur-
rent hypothesis, namely that the mesoloph (-id) is vestigial or absent
in molars of cricetines inhabiting open country and scrubland.
(Hershkovitz, 1955: 644.)" Actually, the phenomenon exemplifies
more than a hypothesis. It is a demonstration of a basic principle
in cricetine evolution.
Variability in the dental pattern of some species led Hooper (op.
cit., p. 53) to the conclusion that extraordinary reliance cannot be
placed on accessory lophs and styles in the systematic analysis of
the genus Peromyscus. No one would quarrel with this opinion. It is
necessary to emphasize, however, that Peromyscus, as currently con-
stituted, is unique among cricetines in containing some species which
are ecologically and morphologically transitional between sylvan and
pastoral groups. No question arises regarding the validity of dental
characters in the systematics of species and genera whose evolution
from sylvan to pastoral forms is no longer marked by contemporary
annectants.
Dynamics of Rodent Molar Evolution
Dental modifications in the phylogenetic line leading to rodents
were associated with hypertrophy of the incisor pair accompanied by
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 83
a progressive decrease in number of teeth and a compensatory in-
crease in the functional area and efficiency of the cutting, crushing, or
grinding surfaces of the remaining cheek teeth. Loss of the primitive
first and third incisors was adequately compensated by development
of ever-growing median incisors that maintain virtually permanent
cutting surfaces on an even and efficient operating plane. Loss of
the first two premolars, and suppression, or reduction in number or
size, of the last two, may be attributable in part to the increasing
demands for calcium and alveolar space by the middle incisors and
in part to the usurpation of their functions by those teeth. In many
rodents, additional specializations of the incisors as seizers, diggers
or triturators are correlated with simplification and reduction in num-
ber of the true molars. In extreme examples, the molars may degen-
erate into simple tools that serve merely for gripping food, or for
mixing and blending with saliva the food already adequately com-
minuted by the incisors.
With establishment of the definitive rodent dental formulae, earli-
est molar modifications leading to the generalized pattern in cricetines
and other rodent groups was accomplished by the process of plication,
described below. Subsequent changes in molar structure have been
effected by forces acting on the vertical and horizontal planes of the
teeth. The processes described in the following as planation and
hypsodonty operate in opposing directions of the vertical axis of the
molar. Lamination, involution, triangulation and fusion model the
molar in a horizontal sense. The first three horizontal forces are
progressive and result in secondary complications. The fourth hori-
zontal force, fusion, is retrogressive and results in secondary simpli-
fications of the generalized plicident pattern. All processes involved
are determined by inherent factors controlling growth and develop-
ment. They operate in a definite direction throughout the evolu-
tion of the organism.
Plication
Plication, or infolding, of the enamel covering of the primitive
upper brachyodont cheek tooth defines the hypocone, procingulum,
postcingulum, connecting ridges between the main tubercles, certain
styles, and a mesoloph (cf. pp. 76-80; fig. 10, A). The mesoloph,
when present, develops from the longitudinal ridge (mure of Wood
and Wilson, 1936; Langsgrat of Schaub, 1925) connecting the pro-
tocone and the hypocone and extends transversely nearly or quite
to the outer border of the molar. Plication of the lower cheek
84 FIELDIANA: ZOOLOGY, VOLUME 46
tooth originates similar topographic features. The additaments of
plication enumerated above result in a complex crown pattern of
5 transverse ridges (anticlines of Stehlin and Schaub, 1951, p. 30)
separated by 4 valleys (synclines of Stehlin and Schaub, loc. cit.)
opening on the outer side of the upper tooth and the inner side
of the lower. The oldest known rodent with the complex plicident
or pentalophodont molar pattern is the late Eocene Theridomys
Jourdain (fig. 13) of Europe. Here the middle transverse ridge
of the molar is the mesoloph fused with the mesostyle. Early crice-
tines such as Eumys, Schaubeumys, Cricetodon, Heterocricetodon, etc.,
show the mesoloph and mesostyle as either fused or independent
structures. The same basic pattern, with slight modifications, has
been acquired, probably independently, in the upper molars of the
more generalized representatives of Castoridae, Eutypomyidae,
Eomyidae, etc. (cf. Wood, 1947; 1955, pp. 165-185).
Recent American cricetines with complex plicident molars typi-
fied by the fused mesoloph and mesostyle include the species of
oryzomyine 1 , thomasomyine 2 and some peromyscine 3 rodents (figs.
4, A; 10, A; 11, A, B). These mice are primarily forest-dwellers. In
deforested country they may survive in wooded ravines, shrub-
covered cliffs and along brush-lined streams. They feed on her-
baceous plants, pulpy fruits, soft seeds, fungi, and invertebrates.
Grains do not constitute a significant part of the normal diet of
woodland-inhabiting mice. Except for minor exceptions, it is un-
likely that their diet and feeding habits have changed appreciably
through geologic time. Adaptive radiation among these mice has
affected external characters most, dental structure least. Known
fossils of early Tertiary rodents of Europe and North America
currently classified as cricetines are not ancestral to present forms.
Most of them are more specialized dentally, but they may be
offshoots of the same basic forest-inhabiting stock that has per-
sisted without important modifications to this day.
A second division of cricetines with plicident molars consists of
nearly all remaining forms, including the phyllotines of this mono-
graph, sigmodonts, akodonts and pastoral peromyscines (Podomys,
1 Composed of Oryzomys (subgenera:Microryzomys, Oecomys, Melanomys,Neso-
ryzomys), Neacomys, Scolomys, Nectomys (s.g., Sigmodontomys) , Megalomys. For
characters see Hershkovitz (1944, pp. 12-13).
2 Thomasomys (synonyms: Aepeomys, Inomys, Delomys, Erioryzomys, Wilfred-
omys), Phaenomys, Nyctomys, Otonyctomys, Rhipidomys. The "Acodon" dorsalis
Hensel, of Schaub (1925, p. 89, pi. 5, figs. 8, 10), the molars of which were care-
fully described by him as typical of the present group, is a species of Thomasomys.
3 Peromyscus (Peromyscus, s.s. [part]; Ochrotomys, s.g.; Megadontomys, s.g.).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS
85
Haplomylomys, Onychomys, Baiomys, Reithrodontomys [s. s.], Neo-
tomodon, Scotinomys, Nelsonia, Neotoma, Xenomys, Ototylomys and
Tylomys). Their molars are characterized by all topographic fea-
Pf, SFI SF2
PF2
FIG. 13. Primitive pentalophodont molar
plan in Theridomys (European Eocene; after
Stehlin and Schaub, 1951, fig. 23): A, upper
right second molar; B, buccal aspect of same.
For explanation of symbols see figures 9 and 10;
mls= fused mesoloph and mesostyle.
tures of the primitive plicident tooth, except that the mesoloph
(and mesolophid) is never locked with the mesostyle (and meso-
stylid) in the unworn tooth; the mesoloph (id) is either reduced
or absent in m 1 ^- 1 , vestigial or absent in my--, and absent in m 3 .
Thus, the unmodified crown pattern of the upper molar normally
consists of 4 complete transverse ridges and 3 valleys opening on
the labial border. The mesoloph sometimes present in m 1 ? may
be sufficiently developed to appear as an incomplete middle or "5th"
crest (fig. 10, B). An occasionally present "pseudomesoloph"(-id) in
the form of either a thickened mesostyle or an enamel evagination
from the posterior border of the paracone (or from the anterior border
of the entoconid) does not affect the basic crown pattern (fig. 12).
According to Schaub (1925, p. 91) and Stehlin and Schaub (1951,
pp. 169, 324, and elsewhere in the text), the simplified or tetralopho-
dont cricetine molar differentiated from the complex, or pentaloph-
odont, molar by regressive loss of the true mesoloph. This view is
certainly correct. It is evidenced by the progressive simplification
86 FIELDIANA: ZOOLOGY, VOLUME 46
of the molar to the trilophodont, bilophodont and cylindriform pat-
terns (fig. 10), by analogy with other regressive elements in the
molars of living cricetines and all other mammals, and, most con-
vincingly, by ontogeny. The American fossil record is poor. There
is a predominance of specialized pastoral forms, which are uncritically
classified. Nevertheless, it does not contradict the present concept of
phylogenetic sequence. The possibility that cricetines with simpli-
fied molars are collateral offshoots from a common ancestor with
plicident molars in the premesoloph stage of development, can be
discounted. The rudiment of a mesoloph, often present in tetra-
lophodont molars of cricetines, is a vestige derived from, and not an
emergent structure leading to, the pentalophodont molar pattern.
The fused mesoloph-mesostyle(-id) is present only in bunodont,
brachyodont molars. It may also be absent in such molars but it is
never present in the specialized, hypsodont molars of cricetines.
Living cricetines with the simplified molar pattern are primarily
pastoral, i.e., inhabitants of deserts, tundras, punas, savannas, scrub-
lands and coniferous forests. Sometimes they occur as intrusive ele-
ments in bogs, meadows, or rocky situations within deciduous forests.
A few aquatic species have survived in riverine habitats subsequently
surrounded by climax forests; others may have invaded streams with
banks deforested by man. The vast majority of pastoral species are
ground-nesting, but many are good climbers and some have become
semi-arboreal. A few species are aquatic. All feed mainly on grasses,
lichens, mosses and grains. Some include pine needles and bark;
others add insects, worms and small fish to the diet. The impact of
this food, especially of harsh or siliceous grasses, on the molars, is
considerably greater than that of the diet of forest-dwelling species
with pentalophodont molars. The natural selective effects of the
different feeding habits may account for the initial differentiation
and subsequent radiation of the simplified, or tetralophodont, molar
pattern.
The six processes of molar evolution described below have acted
on the tetralophodont cheek tooth. Only the first process, planation,
has had a moderate effect on the complex pentalophodont molar of
some American cricetines.
Planation
Figures 14, 49
Once a complicated system of dental peaks, ridges and valleys
has been developed, the process of planation may set in. As a rule,
crested
terraced
plane
FIG. 14. Molar planation: evolutionary stages from primitive crested to
specialized plane shown in front views of molars (upper row) and side views of
molar rows. l = protocone(-id); 3 = paracone in upper, metaconid in lower (after
Hershkovitz, 1955:649).
87
88 FIELDIANA: ZOOLOGY, VOLUME 46
it advances simultaneously with hypsodonty. In either primitive
(i.e., complex) or simplified molar types, early stages of planation
are bilaterally unequal. Here the inner side of the upper molars
and the outer side of the lower rise less rapidly. The terraced molar
(fig. 14) that results is a recognizable and phylogenetically important
stage in the succession of dental topography. In many species with
plane molars, a terraced condition may persist in the newly erupted
but unworn molars of juvenals. As a rule, the upper molars are in
a more advanced stage of planation than the lower, and the third
molar is more advanced than the other molars of the same jaw.
The pentalophodont pattern in living New World cricetines tends
to retain its primitive bunodonty. Nevertheless, planation has pro-
gressed as far as the terraced stage in a number of oryzomyine and
thomasomyine species. 1 On the other hand, the tetralophodont
molars of New World cricetines show all stages of planation from
the fully bunodont, or the crested, through the terraced to the
completely plane. Examples of complete planation in molars of
non-cricetine rodents with or without mesolophs, and in other orders
of mammals, are too well known to require citation.
Hypsodonty
Figure 15
Hypsodonty is the evolutionary process that provides a longer
wearing surface by an increase in the depth of the tooth. It is a
rejuvenating process that counterbalances the effects of planation
on teeth exposed to excessive attrition. Hypsodonty may result in
either an elongate or a prismatic crown or in hypertrophy of the main
tubercle or tubercles of the crown. These effects of hypsodonty
may be described in two categories, as follows:
1. Coronal hypsodonty: Vertical elongation of the entire crown of
the tooth at the expense of the root. This kind of hypsodonty is found
only in molariform teeth specialized for crushing and grinding. It is
typically present in grazing animals. New World cricetines with the
primitive pentalophodont type of molars are forest-dwellers and, in
the main, non-grazers. Coronal hypsodonty among them is absent
or, at most, incipient. The quasi-pentalophodont molars of the Chi-
nese hamster Cansumys, however, are not only hypsodont but seleno-
dont as well, an exceptional tooth form in cricetines. The degree of
1 In the Malagasy murid Gymnuromys (fig. 16, D) specialization of the penta-
lophodont molar has reached the wholly plane condition.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 89
hypsodonty in cricetines with the simplified or basic tetralophodont
molar pattern reflects the extent to which each species has become
adapted to the diet of savanna and scrubland vegetation. In most
phyllotine rodents, the molar crowns are slightly to moderately hyp-
sodont. The condition is more pronounced in sigmodonts and neoto-
mines. Among murids in general, maximum development of coronal
hypsodonty at the expense of the roots has been attained by micro-
tines. Caviomorphs offer additional examples of molar crown hypso-
donty. The classic example of coronal hypsodonty is the prismatic
molar of the modern equine.
2. Tubercular hypsodonty: Elongation of the coronal tubercle, or
tubercles, at the expense of the remainder of the tooth, including the root.
This type of hypsodonty is an adaptation for seizing, grappling,
stabbing, cutting, chopping or cracking. It may appear in any kind
of tooth. The middle incisor of all rodents is an example of tubercu-
lar hypsodonty. The chisel-shaped tooth has developed in depth at
the expense of its own root and the erstwhile root-encasing alveoli
of the lost incisors, the canines and one or more of the premolars.
The elephant tusk is another notable example of tubercular hypso-
donty of the incisor. Canine teeth of many mammals are also
hypsodont tubercles, but the root has persisted in most.
Tubercular hypsodonty of the molariform teeth is well developed
in many marsupials, insectivores and insectivorous bats. It is also
present in some cricetines, particularly the insect-eating Onychomys
and in the fish-eaters Rheomys, Ichthyomys, etc. Here, the molar
cusps have developed into prong-like projections for seizing and
cracking elusive, hard-coated, mobile prey. The spiked cusps of the
insect- and fish-eating rodents are quickly eroded but not before the
peculiar seizing and chewing patterns have become established. In
the central African murid Deomys (Deomyinae) the molar tubercles
are notably elongated and those of both sides of the upper molars
are hooked backward. Evidently, the primary function of the mo-
lars of Deomys (fig. 15, B) is the grappling and chopping of such
wiggling, soft-bodied prey as earthworms and caterpillars. The
molars appear to be of little value as crushers and grinders even
when worn.
The history of hypsodonty and its correlation with the type
and mineral content of plants eaten by herbivorous mammals has
been reviewed by White (1959, p. 211). This author defines three
kinds of molar hypsodonty. Type 1, called cusp hypsodonty, corre-
sponds roughly to my coronal hypsodonty. I do not, however,
C
'v
03
.s
i
g
C
s>
^
03
^
^
C
*""{
^
O
3
*^^
s --^
**
=c
.^
en
^
0)
^
o
o
**
Q
73
O
"8
en C
a oj
^
'oT
*! *"~1
J>
03
^H ^H
*
_C
' ^
O>
73
13 >i
c S
o .
'en
CD
o
Q
O
O>
T? ^
-4-5
73
B
C3 ^
o>
'E
3
CO
S
w
Jl ^
.2 ~
73 2
,S
> ^
^H
03 .
03
S
s
K
J *
.S ^
V
^
CO j
C 5
<3
w
<D CJ
o 2
O)
rC
I
" a oT
c*
4J
O
o
1
"3 .S
o -*-
c^ o^
J-l ^J
,
J3 ^
rrt ^
^
o
^O t-
g ffi
J2
73
en
K
c ^
O en
*" H 5r
C
,
^^ O)
"8 42
03
o
>,|
t*>
^j
t~,
" O
1-
O g
73
C
<v
a
a
3
73 CD
en o
a ^
||
03
J
^ E
C
3
M-i
03 J
b s
en
"3 "o
2 !o
IM
&
u
O
0)
j_
t. a
^
^ >
F^ ^3
0) g
OJ
,
5 a
r^ .
^
03
^ a
3
*^
U
s
-1
3
f-t f\
-g
o>
'en
u
3
C
"o ^
1?
^ J^
'^
"03 *o
2
3
^S QJ
_C
*-" 1
C
en
O
en
X! Ol
>
S fe
O _W
+9
-
-C
>
5
5
psodonty
ropean m
O
1
a
O
O
en
a
x
. C8
g-
o i
1
en *S
>> 3
^
j_
a ^
>,
^ r^i
03
-2
>> c
H
5
H
i -
I-
|
O>
u
^2
3
-C "
C -M
-1
O v
E-<
H
tyj -C
j
. 3
CO
. C8
S
H
<< ^3
m
d
Q ^
C
o
o>
03
j C^
73
EH
90
CO
91
92 FIELDIANA: ZOOLOGY, VOLUME 46
regard the Suidae, included by White in type 1, as a family char-
acterized by hypsodont molars irrespective of some individual ex-
ceptions. White's type 2, tooth-base hypsodonty, should, by defini-
tion, exclude anything assigned to type 1. It seems to me, however,
that molars of most of the taxons included in type 2 can just as
well be referred to type 1, while others, as suggested by White,
can be treated as intermediate between types 1 and 2 or made
subjects of a separate category. Type 3, named root hypsodonty,
includes animals with molars which, in my opinion, can be in-
differently referred to either type 1 or 2, and molars of other animals
which are rootless according to all authorities, including White.
Elsewhere, White (cf. p. 260) equates hypsodonty with "high
crowned" only.
Whatever species or genera he may have had in mind in erecting
the three types of hypsodonty, White cites only supergeneric taxons,
mostly families and orders, as products of each type. He feels
(p. 261) that not enough is known of the larger groupings of hypso-
dont mammals to permit a satisfactory categorization of the lower
taxonomic grades. In the present discussion, however, I prefer
to regard hypsodont teeth as parts of specific animals. Such teeth
can be classified by any convenient standard which serves to illus-
trate the effects of hypsodonty on their form and function.
Lamination
Figures 16, 17
Lamination is the process of transection of a molar crown by con-
fluence of a fold of one side of the tooth with another of the opposite
side. The lamina formed is composed of one or more elements (cusp,
conule, loph or "lophostyle") of one side of the tooth combined with
at least one analogous element of the opposite side of the tooth.
Lamina are classified according to their orientation relative to
the antero-posterior axis of the molar.
1. Transverse: Formed by confluence of opposing, transversely
directed folds. Transverse folds are common among rodents in gen-
eral. They are present in the simplified, or tetralophodont, pattern of
some living cricetines, including phyllotines with unworn or slightly
worn molars (fig. 44, c [m 4 ], fig. 69, e [m T ]), but are absent in the
pentalophodont molars of New World cricetines. However, they
occur in a highly specialized group of the European Miocene repre-
sented by Neocometes Schaub and Zapfe (fig. 16 C).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 93
2. Oblique: Formed (a) by confluence of a fold of one side with
either the anterior or posterior alternating fold of the opposite side,
or (b) as a transverse lamina but with the entire molar rotated
approximately 20 to 90. Oblique lamina are present in the molars
of many caviomorphs and other rodents, including some living
species of tetralophodont cricetines (fig. 68, c [m 3 -]).
3. Chevron: Formed by confluence of obliquely directed opposing
folds. These folds are present in some caviomorphs and murines
but are absent in cricetines.
The figure 8 pattern in simplified tetralophodont molars of many
cricetines is a condition of incomplete transverse lamination between
opposite folds. The same design may also occur as a residue in lami-
nated molars worn to the base of the folds.
Subdivision of a lamina into its original components may be ef-
fected by the processes of involution and triangulation, defined below.
Involution
Figures 16, 17
The whole or part of a planed molar crown may be modified into
a C-, or E-, or 5-shaped pattern by varying degrees of penetration
of each of the enamel folds. For this modeling process, the embryo-
logical term involution is used. Thus, involution, like lamination, is
one of the manifestations of plication in the specialized molar.
The C (or < ) pattern is derived from involution of a single lamina
(partial or complete; see Lamination above). A double C (or ^)
pattern can be derived from a bi- or trilaminate molar. A C-shaped
pattern may form, also, in third molars in which all folds except
either the major or the second primary fold are obsolete or absent
as a result of simplification or excessive wear. This C-shaped pat-
tern of involution is not to be confused with a similar pattern formed
by secondary fusion (see below) of two lamina on only one side of
the tooth. The C-shaped pattern is not present in phyllotines, except
sometimes secondarily in the third molar, as a result of excessive
wear, rather than involution (cf. fig. 67, g [m*]).
The sigmoid or 5-shaped pattern is derived from involution of a
simplified molar with the procingulum and postcingulum greatly re-
duced or absent (fig. 69, e, fig. 67, b-g [m 7 ]). A modified sigmoid
pattern in upper molars retains indications of the first primary and,
sometimes, of the second secondary folds. In the simple sigmoid
pattern, first primary and second secondary folds are suppressed.
pstc.
P2
FIG. 16. Lamination and involution (for names of all cusps, lophs and folds
see fig. 9). See opposite page for explanation.
94
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 95
The sigmoid pattern in lower molars is an inverted mirror image of
that of the corresponding upper molars of the same side. Sigmodont
rodents are so called because of the S-shaped pattern of their third
lower molars. In Euneomys, the sigmoid pattern characterizes all
molars. Both sigmoid and modified sigmoid patterns occur among
phyllotines.
The E, or epsilon, pattern is the sigmoid pattern with a well-
developed procingulum in the upper molars and a well-developed
postcingulum in the lower molars (fig. 67, d-f [m^]).
Involution appears most commonly in cheek teeth in the planed,
hypsodont stage of phylogeny. The process may operate before,
after, or simultaneously with, the processes of lamination and tri-
angulation.
Triangulation
Figures 16, F, 69, c, 115, 116
The process of triangulation is the modeling of circular or ovate
cusps, cingula, and lophs of a planed hypsodont molar into more or
less triangular-shaped elements with apices at crown borders. Tri-
EXPLANATION OF FIGURE 16
A. Transverse lamina in the African murid (Otomyinae) Otomys ores/ex Thomas
(upper right molar row). Note the supernumerary laminules and folds of the
postcingulum (pstc.) of m a .
B. Partial transverse lamination in the South American murid (Cricetinae)
Irenomys longicaudalus Philippi (upper right molars). Note the 8-shaped pattern
of m 2 .
C. Transverse, oblique and involuted lamina in the European Miocene murid
(Cricetinae?) Neocometex brunonis Schaub and Zapfe (lower left molars, after
Schaub and Zapfe, 1953, pi. 1, fig. 13).
D. Transverse, oblique and involuted lamina in the Malagasy murid (Neso-
myinae) Gymnnromys roberti Forsyth Major (lower right molars, after Stehlin
and Schaub, 1951, fig. 577, reversed). The resemblance in enamel pattern between
Gymnnromys and Neocometex is striking. However, the order of size of the molars
in the former is the reverse of that in the latter and indicates that each genus
may belong to a different phyletic line within the Muridae.
E. Oblique partial lamination in the West Indian caviomorph (Capromyidae)
Plagiodontia hylaeum Miller (? = P. aedium F. Cuvier] (upper right premolar and
molars).
F. Chevron-shaped partial lamination in the South American caviomorph
(Abrocomidae) Abrocoma bennetti Waterhouse (lower left premolar and molars);
the general pattern of the upper cheek teeth is as in B, an unusual combination.
G. Chevron-shaped lamina in the Philippine murid (Murinae) (Crateromys
Kchadenbergi Meyer (lower left molars).
96
FIELD IANA: ZOOLOGY, VOLUME 46
FIG. 17. Lamination and involution (for names of all cusps, lophs and folds,
see fig. 9).
A. Lamination and involution in second right upper molar of the South Amer-
ican caviomorph Dinomys brannicki Peters.
B. Lamination and involution in second right upper molar of the South
American caviomorph Dactylomys dactylinus Desmarest.
C. Involution in second left lower molar of the South American cricetine
Phyllotis micropus, with resultant E=, or epsilon pattern.
D. Involution in third left lower molar of Phyllotis micropus, with resultant
modified S= pattern.
E. Involution in second left upper molar of the South American cricetine
Euneomys chinchilloides, with resultant S= , or sigmoid pattern.
angulation may precede, follow, or operate simultaneously with,
lamination or involution, or both, in the same tooth row. The
process of triangulation has reached its highest degree of develop-
ment in microtines. Good examples of triangulation also occur in
the grass- and scrubland species of Neotoma. There are some in-
stances of triangulation among phyllotine rodents, but Andinomys
is the only notable example.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 97
Fusion
Figures 10, 18
Reduction or elimination of a fold between two dental elements
leads to the partial or complete fusion of these elements. Reduction
or elimination of the elements themselves is not fusion. Individual
folds are reduced by compression and eliminated by isolation and /or
coalescence.
nil)
Pt2
D
FIG. 18.- -Fusion and oylindrification (for names of all cusps, lophs and folds,
see fig. 9 and also compare with fig. 10).
A. Isolation of the major fold (m/) in the second right upper molar of the
heteromyid Dipodomys merriami Mearns, with resultant fusion of protocone (/)
and hypocone (2).
B. Lamination and fusion in second right upper molar of Heleromys gaiimfri
J. A. Allen and Chapman. Fusion of hypocone (2) and posteroconule (16) is
the result of isolation of second minor fold (nf 2} and its coalescence with second
secondary fold (/ 2).
C. Fusion of all cusps in first and second right upper molars of the geomyid
Orthogeomys cuniculux Elliot as a result of isolation, compression and elimination
of coalesced major fold (mf) and second primary fold (pf 2). The two molars have
become cylindriform.
D. Fusion of all topographical elements in each of the upper right cheek
teeth of the late Oligocene cylindrodont Tsagnnomys altaicus Matthew and Granger,
as a result of the elimination of all folds. All cheek teeth have become cylindriform.
98 FIELD IANA: ZOOLOGY, VOLUME 46
Compression. With advancing hypsodonty and lamination (in-
cluding involution and sigmation) enamel folds tend to become
narrower antero-posteriorly (cf. Euneomys, fig. 69, e). In the Lago-
morpha the folds are compressed to transverse serrated lines.
Isolation. True internal folds (fig. 9, IF) are isolated remnants
of larger folds that opened on the margin of the tooth. They are
present in the molars of New World pentalophodont cricetines but,
with a few exceptions, have disappeared from the molars of New
World tetralophodont cricetines. In pentalophodont cricetines, the
first secondary fold, between paracone and mesoloph, is commonly
isolated but the dental elements themselves are normally discrete,
except in an extremely worn tooth. In some pentalophodont and
many tetralophodont cricetines, the second secondary fold of the
upper and the second primary fold of the lower molars, most fre-
quently the third, may be mere enamel islands before they are effaced
by slight attrition. Complete isolation, or loss, of the second sec-
ondary fold in tetralophodont cricetines and other rodents, results
in a trilophodont molar pattern. Elimination of the second second-
ary and first primary of the upper molars produces the bilophodont
or 8-shaped pattern. Isolation of the major and second primary folds
that define the figure 8 leads to complete fusion (not loss) of all com-
ponents of the primitive tri- or quadritubercular molar.
Coalescence. Two or more folds of the same side of the molar
may coalesce as a consequence of compression, isolation, or obsoles-
cence, of a cuspule or loph. The result is the ultimate loss of the
identity of one of the folds. The internal folds of pentalophodont
cricetines are often coalesced with either a primary or a secondary
fold. In tetralophodont cricetines, where the mesoloph is absent or
obsolete, the first secondary fold is coalesced with the second primary
fold and has no separate identity.
Confluence of a fold of one side of the molar with another of the
opposite side, such as the union of major and primary folds in some
species, results in lamination and is not coalescence. However, such
confluent folds are also subject to the process of fusion. They may
become compressed, isolated, and eventually eliminated.
Cylindrification
Figures 10, 18
The end product of molar evolution in most pastoral rodents and
many other mammals is the cylindriform molar. This is a completely
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 99
fused molar. The process of cylindrification is, therefore, an exten-
sion of fusion. However, the structural and time gaps between fusion
of a secondary fold in the primitive pentalophodont molar and elimi-
nation of the major fold in a simplified prismatic molar are so great
that cylindrification must be recognized as a distinct stage, the last
stage, in a line of molar evolution.
Fusion and cylindrification are retrogressive processes as they
apply to the enamel pattern of the molars. Evolution of the organ-
ism itself, however, may be progressive pari passu with retrogression
and loss of some or all of its dentition.
Cylindrification is most common among the Edentata. The cy-
lindrical cheek teeth of the Oligocene cylindrodontid rodent Tsagan-
omys Matthew and Granger are representative. The processes of
fusion and cylindrification are well exemplified in modern forms of
Heteromyidae and Geomyidae.
Differential Evolutionary Rates in Upper and Lower Molars
of New World Cricetines
Evolution of each upper molar in cricetines proceeds at a different
rate and does not always involve the same stages of evolution as its
equivalent in the lower jaw. Evolution of the last molar, upper or
lower, is more advanced than in the tooth before it. Differential
rates of evolution between molars individually and between those
of the upper and lower jaws collectively, result from the position of
the teeth in their mortar-pestle relationship. Structural changes in
the upper molars, the passive mortar, reflect the shifting movements
and changing shape of the pounding, pulverizing lower molars, the
pestle. Because of its terminal position, the first molar has the most
varied functions, hence the most complex design. The second molar,
situated at the center of the masticatory surface, has the simplest
functions and is the most uniform in structure. The third molar,
crowded toward the fulcrum, has a minimum use and tends to dis-
appear altogether. This is true of cricetines but not of rodents in
general (cf. fig. 16, A, D, where the third molar has evolved into the
dominant tooth).
The process of planation, which normally proceeds apace with
the compensatory process of hypsodonty, is usually more advanced
in the upper molars. Among phyllotines, especially in Phyllotis,
slightly terraced lower molars are commonly associated with plane
upper molars. In any case, the third molar, upper or lower, is more
100 FIELDIANA: ZOOLOGY, VOLUME 46
planed than the second and the second is more planed than the first.
At the same time, the upper molars may be laminating while the
lower molars are undergoing triangulation or involution.
The order in which each molar element degenerates and disap-
pears is generally the reverse of the order in which it first appeared.
The older the element in phylogeny the longer it persists in the indi-
vidual and in the species. The last important structural complex
to formulate the cricetine pentalophodont molar, namely the fused
mesoloph-mesostyle(-id) is the first to disintegrate into its compo-
nents and disappear altogether. As a rule, the mesolophid disap-
pears first, then the mesoloph. Procingulum and postcingulum break
down next. However, the evolutionary relationship between these
complexes in upper and lower molars is not on the same order as that
existing between mesolophostyle and mesolophostylid. Although
the upper procingulum is less specialized than the lower, it usually
becomes obsolete first.
The original crests of the quadritubercular rodent molar are the
last to be affected. The hypocone(-id) may be lost entirely but the
protocone(-id), paracone, metacone(-id) and entoconid degenerate
by fusion (cf. p. 99) into the cylindriform molar. The first cylin-
driform cricetine molar is m-. This tooth is also the first to disap-
pear in more advanced murids (cf. Desmodilliscus, Rhynchomys, etc.).
The order of disappearance of enamel folds corresponds to that of
the elements they define. Thus, in the upper molar, the first second-
ary fold is lost first, the second primary fold last.
Degeneration of molars through wear, i.e., ontogeny, follows
essentially the same sequence as degeneration through phylogeny.
Third^Molar
The cricetine third molar is the last to appear in ontogeny and
the first to disappear in phylogeny. All evolutionary stages of sim-
plification from pentalophodont to cylindriform molar are displayed
first in the third molar. This tooth is usually terraced and frequently
plane, while first and second molars are still crested. The specialized
character of lamination is most frequently established first in the
third upper molar. This is balanced by the appearance of sigmation
in the third lower molar. The second minor fold, a novelty of the
tetralophodont molar, first appears in the third molar, usually the
upper. Fusion and loss of cingula and hypocone occur in the third
molar, usually first in the upper, well in advance of first signs
of the same degeneration in other molars.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 101
Phylogenetically significant dental characters in the process of
disappearance become progressively less evident on the crown sur-
face of unworn teeth. Conversely, new characters in the process of
establishment become progressively more evident and persist longer
through wear. A mesoloph in the process of disappearance (palin-
genesis) and a second minor fold in the process of establishment
(caenogenesis) may occur simultaneously in the unerupted or unworn
third upper molar.
The third molar of most pentalophodont, or sylvan, cricetines is
not functional before the animal is subadult and sexually mature.
In tetralophodont, or pastoral, cricetines, including phyllotines, the
third molar erupts before or shortly after birth and is functional in
the juvenal mouse. Time of eruption of the third molar advances
with increasing complexity of the high-crowned molar. Conversely,
eruption is retarded with degeneration of the low-crowned molar.
Molar Roots
The primitive number of roots of the cricetine first molar may
have been four. The roots become fewer as the tooth becomes more
specialized, and the reduction in number is greater in the lower than
in the upper first molar. In the following list the number of upper
and lower roots of the first molar of each phyllotine species is shown :
} = Phyllotis darwini; P. griseoflavus; P. gerbillus; P. pictus;
Pseudoryzomys wavrini;
Galenomys garleppi; Eligmodontia typus; Calomys spp.
~ = Phyllotis amictis.
4 = Phyllotis sublimis; P. micropus; Calomys spp.
- 1 ., 4 = Phyllotis boliviensis.
II = Zygodontomys spp.
% = Andinomys edax; Chinchillula sahamcu.
Upper Incisor
Figures 19, 20
The generalized upper incisor of rodents is slender or moderately
thickened, with the terminal half slightly recurved and the cutting
edge lying on a horizontal plane or at a slight angle. The anterior
102 FIELDIANA: ZOOLOGY, VOLUME 46
face is smooth and normally pigmented yellow, orange or reddish.
As a rule, the vertical length, measured in front, is about one-half
the length of the diastema. The generalized upper incisor, common
to most rodents, has been drastically modified in many species.
The specialized upper incisor may be markedly thick or slender,
extremely recurved (opisthodont), straightened (orthodont), thrust
forward (proodont), or flexed inwardly. The anterior face may be
unpigmented, grooved, or striated. The cutting edge may be acutely
angular, and the whole tooth may be disproportionately lengthened
or shortened. All modifications of the upper incisor are related to
molar specialization. In many cases, a correlation with modifica-
tions of the palate is obvious. A few of the more striking divergents
from the generalized form of the upper incisor are described in the
following.
Degenerative. The upper incisor may degenerate progressively
with deterioration of the cheek teeth. This process is generally asso-
ciated with a compensatory elongation and attenuation of the muzzle,
especially notable in the diastemal portion of the palate. Incisor
degeneration has not occurred among phyllotines. Other murids,
however, afford examples. The upper incisor of the Celebesian Echi-
othrix leucura Gray is short, weak, faintly grooved and orthodont.
The diastemal portion of the palate in this species is elongate. The
diastema of the lower jaw, however, is not proportionately produced
but the very long slender lower incisor bridges the gap to make occlu-
sion. The inner row of cuspules of the upper molars are reduced and
the corresponding ones of the outer side of the lower molars are obso-
lete or fused. 1 The process of incisor degeneration associated with
loss of pigmentation, diastemal elongation, and molar degeneration
is extreme in the Philippine shrew rat Rhynchomys soricoides Thomas
(fig. 20, A-C). Here, the first and second molars of upper and lower
jaws are practically functionless, the third molars have disappeared
and the lower incisors are short and extremely fine. In all, the max-
illo-mandibular region approaches the condition existing in the xen-
arthrous and monotreme anteaters. Rodents of the type described
are small-eyed burrowers. They probably feed mainly on earth-
worms and grubs in addition to soft, ripe fruit.
Seizer-digger. The upper incisor may increase its utility while
the cheek teeth become simplified in form, specialized in function,
and reduced in number. The highly specialized seizer-digger incisor
1 This condition simulates a reversal from the typical triserial cuspidate pattern
of murines to the biserial arrangement characteristic of cricetines.
OPISTHODONT
D
ORTHODONT
B
PROODONT
ai-
Fio. 19. Forms of incisors in phyllotines: AC, curvatures with reference
to the basal-incisive plane (a-6) and vertical-incisive plane (c d). D, incisors of
Andinomys edax: 1, front view of upper and lower incisors; 2, cross section of
upper incisors above cutting edge. E, incisors of Phyllotis danrini: 1 3, variation
in outline of cutting edge of upper incisors; 4, lower incisor; 5, cross section of
upper incisor above cutting edge.
103
104 FIELDIANA: ZOOLOGY, VOLUME 46
is, as a rule, slender, markedly elongate, proodont, slightly or not at
all scored longitudinally on its anterior face, and lightly or not at all
pigmented (fig. 20, D). It is adapted for use as a pick in digging
and for cropping short shoots or seizing small insects, larvae, and
earthworms in tunnels or in rocky or cavernous situations where the
hands are of little or no assistance. The gnawing power of the seizer-
digger is probably reduced. The diastemal portion of the palate in
rodents with this type may be long or short but is always attenuate.
Phyllotines with specialized seizer-digger upper incisors are Gale-
nomys, Phyllotis boliviensis and individuals of P. sublimis (figs. 59,
62). Some species of murines combine moderately elongated proo-
dont upper incisors of the seizer-digger type with an elongation of
the diastemal portion of the palate. In these, the mandibular dia-
stema remains short while the lower incisor lengthens extraordinarily
to make occlusion with the upper. The Burmese and Assamese
Rattus manipulus Thomas is a moderately specialized example of
this type with molar degeneration incipient. According to Roonwal
(1949, p. 100) this is a burrowing rat that feeds largely on insects
and earthworms. The seizer-digger characters are more advanced
in the incisor of the Philippine striped rat, Chrotomys whiteheadi
Thomas. Its molars are more simple, with the third nearly vestigial.
This animal is also an earthworm eater (Rabor, 1955, p. 207). The
closely related Philippine rat, Celaenomys silaceus Thomas, is even
more specialized in the same direction. Both Chrotomys and Celae-
nomys are divergents from the same murine stock that gave rise to
Rhynchomys. They are much less nearly related to Hydromys with
which they are currently associated in the superfluous subfamily
Hydromyinae. Extreme examples of the seizer-digger incisor occur
in such unrelated rodents as the Andean cavy (Monticavia), the
Chilean coruro (Spalacopus) , the viscachas (Lagostomus), the African
mole rat (Cryptomys), the Asiatic burrowing vole (Ellobius) (fig.
20, D), and the Oregon gopher, Thomomys bulbivorus. In all, the
incisors are wholly or partially unpigmented.
Triturator. The specialized triturator incisor is short or long,
orthodont or opisthodont, thick, often deeply grooved longitudinally
and usually well pigmented (fig. 20, E). Triturators are efficient
gnawers, choppers, and whittlers, and they function as hoes if used
in digging. Triturators supplement, and may tend to usurp, the
grinding function of cheek teeth. The diastemal portion of the pal-
ate of rodents with the triturator type of incisor tends to become
thick and shorter relative to the basicranial length. The upper in-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 105
r
FIG. 20. Rodent incisors: A, degenerative type in themurid (Rhynchomyinae)
Rhynchomyx soricoidex Thomas, palatal aspect showing long palate and right upper
molars; B, side view of same skull; C, mandible and left lower molars of same;
D, xeizer-digger type in the murid (Microtinae) Ellobius talpinus Pallas; K, tritura-
tor type in the muroid (Rhyzomyidae) Rhizomys pruinosm Blyth.
cisor of some fossorial forms such as the African Tachyoryctes and the
Indo-Chinese Nyctoleptes, combine the special digging qualities of
both triturator and seizer-digger types. Their incisors are elongate,
forward-projecting, thick and heavily pigmented.
The triturating type of upper incisor is not highly developed in
phyllotines. The orthodont upper incisor of Chinchillula sahamae
106 FIELDIANA: ZOOLOGY, VOLUME 46
is comparatively heavy but not definitely classifiable as a specialized
triturator. The upper incisor of Phyllotis micropus is the heaviest
in the genus but is still very near the generalized type. Incisors of
Calomys, Eligmodontia, Zygodontomys and the species of Phyllotis,
other than the one mentioned above, are generalized. Many exam-
ples of highly specialized triturators occur in geomyids, bathyergids,
caviomorphs and castorids. The example figured (fig. 20, E) is of
the Asiatic bamboo rat, Rhizomys pruinosus.
Flexed. The upper incisor of Andinomys (fig. 19, D) is inwardly
flexed, its cutting edge oblique with the sharp point on the outer side.
The paired incisors form a two-pronged instrument. The tips of the
lower incisors taper to a point that fits the angle between the upper
incisors. Incisors of certain fish-eaters (Ichthyomys, Anotomys), the
African dormouse (Claviglis), and the tortoise-headed rat (Lophi-
omys) are of the same type. In Rhagomys and the wood rat (Neo-
toma), the cutting edge of the upper incisors also forms prongs but
the teeth are not flexed inwardly. Even more remarkable than the
shape of the incisors is the great diversity in the form and feeding
habits of the many species of rodents to which they are common.
Grooved. Grooves or striations on the anterior face of the upper
incisors occur sporadically throughout the Rodentia. Their function
or structural significance is unknown. With the exception of Apo-
rodon, grooves or striations are normally found only among tetra-
lophodont rodents. They are often present and usually well defined
in the specialized triturating type of incisor but are absent or poorly
defined in the seizer-digger type.
The systematic significance of grooved incisors in murids is slight
or nil. Nevertheless, their appeal as obvious "key characters" is
great. At one time or another the name Reithrodon, used for a mono-
typic genus of groove-incisored cricetines, was applied to such di-
verse, groove-incisored forms as Phyllotis pictus, Sigmodon alstoni,
Irenomys longicaudatus, Euneomys chinchilloides, Chelemyscus fossor,
and some species of Reithrodontomys.
Among phyllotines, incisors of some individuals of Phyllotis
boliviensis are scored by longitudinal striae hardly or not at all visible
to the naked eye. In P. sublimis distinct striae are usually present
and in P. pictus striae are constantly present and usually well
defined. Striae are sometimes found in the upper incisors of Chin-
chillula sahamae. In Euneomys, a genus nearly related to phyllotines,
the incisor is deeply grooved and of the triturator type.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 107
Lower Incisor
Variation in length, shape, form of cutting edge, and angle of
projection of the lower incisor is correlated with mandibular mobil-
ity, the size and shape of the mandibular processes, and the structure
of the muzzle as a whole. Upper and lower incisors, therefore, do
not show as close a morphological correspondence as exists between
upper and lower molars. 1 Analysis of variation in the cricetine
lower incisor and the interpretation of its significance are subjects
that have not been studied. However, the description of the man-
dible of each species in the following pages includes a reference to the
degree of projection of the lower incisor root. Also, the length and
angle of the exposed anterior portion of the lower incisor are noted
in the description of Galenomys (p. 464, fig. 63), in comparisons be-
tween Phyllotis and the African Mystromys (p. 221, fig. 60), and in
the general discussion of the upper incisor in the preceding section.
Grooving of the lower incisors is rare in murids, absent in crice-
tines. Where it does occur, as in the African Otomys, it is a variable
character and is normally associated with the grooved triturator
type of upper incisors.
Incisor Indices
Relationship of the incisors, upper or lower, to the molar plane
and to the basal-incisive plane (see definitions below) varies from
species to species. Characters revealed by measurements of these
planes are not described in the text (see figs. 59, 60, 62, 63).
Planes of reference used in the illustrations are defined as follows
(figs. 19, 21):
Basal-incisive plane. Defined by a line from the tips of the upper
incisors to the most inferior point of the basicranium (basioccip-
ital, tympanic bulla, paroccipital process, or pterygoid, as the case
may be).
Vertical-incisive plane. Defined by a line projected through, or
tangential to, the upper or lower incisor and vertical to the basal-
incisive or -mandibular plane.
Basal-mandibular plane. Defined as the line projected by those
parts of the inferior border of the mandible that are in contact with
a plane surface.
1 There is no foundation for surmising, as does Landry (1957, p. 223), that
rodents seem to have "evolved a stable lower incisor form and variously adapted
the upper incisor and rostrum to fit it."
108
FIELDIANA: ZOOLOGY, VOLUME 46
Molar plane. Defined by a line connecting the peak of the first
cheek tooth with the peak of the last cheek tooth of either upper or
lower jaw.
FIG. 21. Side view of skull, showing incisive and molar planes: a, vertical-
incisive plane; b, molar plane; c, basal-incisive plane; d, mandibular plane.
\
greatest length
condylobasal
palatal
bullar
length
less tube
FIG. 22. Dorsal and palatal aspects of skull, showing cranial measurements
used in text, o, width of rostrum; b, least interorbital breadth; c, zyjjomatic
breadth; d, mid-frontal width; e, width of braincase.
109
EXPLANATION OF FIGURES 23-25
1. Nasal
2. Frontal
3. Parietal
4. Interparietal
5. Occipital
6. Premaxillary
7. Maxillary
8. Jugal
9. Squamosal or temporal
10. Palatine
1 1 . Presphenoid
12. Basisphenoid
13. Parapterygoid plate
(often fused to basisphenoid)
14. Pterygoid process
(often fused to basisphenoid)
15. Alisphenoid (more or less fenestrated)
16. Auditory, or tympanic, bulla
17. Mastoidal, or periotic, capsule,
or petrosal
18. Orbitosphenoid
19. Lachrymal
a. Capsular projection for upper incisor
b. Preorbital foramen
c. Antorbital, or infraorbital, foramen
d. Antorbital bridge (of maxillary)
e. Incisive, or anterior palatal, foramen
/. Palatal process of premaxillary
g. Palatal process of maxillary
h. Anterior palatal pit (and foramen)
i. Posterolateral palatal pit (and fora-
men)
j. Parapterygoid fossa
k. Sphenopalatine vacuity
I. Mesopterygoid fossa
(between pterygoid processes)
m. Hamular process of pterygoid
o. Petrotympanic fissure
p. Foramen ovale
q. Auditory bullar tube
(eustachian canal)
r. Auditory meatus
s. Occipital condyle
t. Foramen magnum
u. Paroccipital process
v. Glenoid fossa
w. Carotid canal and fissures
x. Mastoidal process
y. Lambdoidal crest
z. Temporal ridge
aa. Optic foramen
66. Sphenopalatine foramen
cc. Anterior lacerated foramen
dd. Zygomatic plate (of maxillary)
ee. Hamular process of squamosal
//. Temporal vacuity
(dorsal and ventral)
110
FIG. 23. Parts of the dorsal aspect of a murid skull. Small figure shows
divergent-sided frontals and angular fronto-parietal sutures. See p. 110 for key
to numbers and letters.
Ill
17
U
FIG. 24. Parts of the ventral aspect of a murid skull. See p. 110 for key to
numbers and letters.
112
~
c
et
E
c
Q
,0
o
I
0.
$
OT
113
EXPLANATION OF FIGURE 26
a. Ramus g. Mental foramen
6. Angular process h Inferior masseteric ridge
c. Condyloid process .
, n ., i. Supenor masseteric ridge
d. Coronoid process
e. Capsular projection *- Mandibular foramen
/. Sigmoid notch k- Symphysis
114
FIG. 26. Parts of the mandible of a murid. A, lateral aspect; B, medial
aspect. See p. 114 for key to letters.
115
SYSTEMATIC REVISION OF PHYLLOTINES
Characters of the Phyllotine Group of Cricetine Rodents
External characters. Body and limbs adapted for terrestrial life
with normal ambulatory, slightly saltatorial, scansorial or natatorial
movements; notable specializations for burrowing, jumping, climb-
ing or swimming absent; body size varying from extremely small to
moderately large for cricetines; pelage normally thick, the individual
hairs long, fine and soft to moderately coarse, never hispid or spiny;
juvenal pelage usually similar in color and texture to adult pelage;
color of nose, ears and rump not reddish or in marked contrast with
remainder of upper parts; tail from less than one-half of combined
head and body length to one and one-half times longer, moderately
to well haired, often pencilled and faintly or sharply bicolor for at
least two-thirds of its length; eyes normal; ears moderate to large in
size, always more than one-half of length of hind foot; hind foot
(fig. 3) not markedly enlarged, well haired above, heel beneath hairy,
plantar surface bare or hairy; pollex with nail; claws of fore and
hind feet not specially modified, the middle claw, measured on ven-
tral surface, one-half or less of length of corresponding digit.
Cranial characters (figs. 22-26). Palatal bridge produced pos-
teriorly to or behind posterior plane of last molars, posterior border
rounded or square, with or without a short median spine; postero-
lateral portion of each palatine bone often excavated or depressed
and always marked by a distinct perforation or by a reticulation of
perforations or pits; mesopterygoid fossa more or less U-shaped or
M-shaped, the pterygoid processes parallel-sided or slightly divergent
posteriorly, but never defining a sharp A-shaped fossa along their
entire length; parapterygoid fossa, seen from ventral surface, usually
shallow and subtriangular or ovate in outline, lateral wall not parallel
to inner wall (hamular process) but gradually merged into dorsal
surface and anterior wall; anterior wall of parapteryoid fossa usually
flattened, rarely undercut to form a deep fossa; sphenopalatine vacui-
ties usually large, the lateral wings of the basisphenoid and pre-
sphenoid thinly ossified and largely fenestrated; incisive foramina
long and narrow, pointed behind and, with few individual excep-
116
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 117
tions, extending posteriorly to or behind anterior plane of first mo-
lars; rostrum not markedly tapered dorso-ventrally from base to tip;
anterior process of premaxillary projected slightly or not at all be-
yond an tero- vertical plane of incisors and never united with antero-
lateral border of nasals to form a tubular projection or trumpet;
portion of premaxillo-maxillary suture below antorbital foramen
situated about midway between first molar and incisor and form-
ing a 90-135 angle to horizontal plane of palate; nasals behind
roughly square, rounded or obtusely triangular, terminating from
slightly in front of to slightly behind fronto-maxillary suture, never
with a long pointed process extending deeply between frontals; supra-
orbital edges square, ridged, beaded or produced as ledges, never
evenly curved; zygomatic arches complete; interparietal well devel-
oped, at least transversely, and with a distinct suture separating
each of its borders from at least two- thirds of the width of parietal
and occipital, respectively; opening of antorbital foramen on dorsal
surface deeply excised, semicircular or ovate in outline, with more
than one-half to nearly full width of zygomatic plate clearly exposed
to view when seen from above; inner side of medio-lateral axis of
antorbital bridge of zygoma never directed posteriorly; zygomatic
plate comparatively high and broad, width more than one-half of
least interorbital breadth, anterior border plane, slightly convex, con-
cave, or, if deeply excised and provided with prominent spine on
upper corner, the incisors not grooved.
Dental characters. Molars well developed, mesoloph(id) absent
or vestigial, at least in m} ; mesostyle(id) when present never fused
with mesoloph(id); ectoloph, enteroloph and second minor folds ab-
sent; first upper molar with three or four roots, lower with two to four
roots; occlusal surface of m^ square or broadly rectangular in outline,
its width at posterior half approximately two-thirds or more of great-
est length of tooth ; third molar usually fully erupted and functional
in active juvenals; m a from one-half to three-fourths of length of m- ;
procingulum of m r not isolated from cusps by confluence of first
minor and first secondary folds; major and primary folds well opened,
not compressed antero-posteriorly; first primary fold of m- 3 reduced
or absent, its length, when present, one-half or less of combined
length of second primary and internal folds (usually fused except,
frequently, in Calomys), long axis of second primary fold inflected
forward, second secondary fold reduced to a small enamel island, or
absent; second primary fold of m s obsolete or absent; outer surface
of each incisor smooth or marked by one or two weakly defined
grooves.
118 FIELDIANA: ZOOLOGY, VOLUME 46
KEY TO SECTIONS, GENERA AND SPECIES OF
PHYLLOTINE RODENTS
1. Upper incisors orthodont, proodont, or opisthodont, with anterior surface
smooth, grooved or striated; upper molars high or low crowned, with flat or
terraced grinding surfaces, the anterior enamel walls of at least the inner upper
and outer lower cusps not thrust upward and back to form rounded crests;
procingulum of m x simple or bilobate, its occlusal surface flat, laminate, sub-
triangular, or subcordate in outline; mesostyle absent or extremely rudimen-
tary; ear, measured from notch, shorter to longer than hind foot; mammae
never more than 8 (PHYLLOTIS section) 4
1. Upper incisors opisthodont, their anterior surface never marked by vertical
grooves or striae; upper first and second molars low or moderately high crowned
with crested surfaces, the anterior enamel wall of each of the four principal
cusps and of procingulum of m 1 thrust upward and inclined posteriorward to
form well-defined rounded crests in unworn tooth; procingulum of m i uniconu-
late or biconulate, its outline in worn tooth broadly ovate with or without an
anterior notch; mesostyle present or absent, when present usually fused with
paracone. Ear, measured from notch, never longer than hind foot; toes of hind
foot variable in length; mammae 6 to 14 (CALOMYS section) 2
2. Mesopterygoid fossa as wide as or wider than parapterygoid fossa measured
at same plane; sides of supraorbital region markedly divergent, the edges
strongly beaded, m- with or without anterior median fold, the procingulum
never clearly divided into two conules in adult; mesostyle often well developed
and fused with paracone; m^ nearly as long as to slightly longer than m^.
Fifth hind toe short, its tip, less claw, not reaching distal end of first phalanx
of fourth toe; mammae 8 Zygodontomys (p. 196)
2. Mesopterygoid fossa narrow, its width less than width of parapterygoid fossa
measured at same plane; sides of supraorbital region divergent or nearly par-
allel-sided, the edges beaded or square. m x with or without anterior fold, pro-
cingulum uniconulate or biconulate; rrig distinctly shorter than m^; mesostyle
absent or extremely rudimentary. Fifth hind toe long or short; mammae 6
to 14 3
3. Sole with three middle postdigital tubercles more or less united to form a thickly
haired cushion; first postdigital tubercle small, naked; fifth postdigital tubercle
reduced or absent; tarsal tubercle small, naked; fifth hind toe long, its tip, less
claw, reaching distal end of first phalanx of fourth toe or beyond.
Eligmodontia (p. 175)
3. Sole with six well-defined, naked plantar tubercles; fifth hind toe, less claw,
barely or not extending as far as distal end of first phalanx of fourth toe.
Calomys (p. 123)
4. Sole with three middle postdigital tubercles coalesced to form a thick, well-
haired pad; size small, greatest length of skull less than 28 mm.; incisors
opisthodont, never grooved Eligmodontia (p. 175)
(Individuals with extremely worn molars may be confused with the Phyllotis
section, hence Eligmodontia is keyed in this as well as in the Calomys section
where it belongs.)
1*. Sole with three middle postdigital tubercles discrete or partially fused at their
base, the tubercles (not surrounding area) entirely naked or set with a few short
inconspicuous bristles; length of skull variable; angle of incisors variable, their
anterior face smooth or grooved 5
5. Upper incisors opisthodont, ungrooved; zygomatic breadth not more than dis-
tance from posterior tips of nasals to anterior border of interparietal; inter-
orbital breadth at mid-frontal plane less than greatest width of rostrum; sides
of supraorbital region divergent and slightly ridged or beaded; mesopterygoid
fossa at base of hamular processes at least as wide as parapterygoid fossa meas-
ured at same plane; sole, including plantar surface of heel, entirely bare; fifth
hind toe, less claw, not reaching distal end of first phalanx of fourth; first hind
toe, less claw, not reaching base of first phalanx of second toe; ear, measured
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 1151
from notch, less than 70 per cent of hind foot length; tail sparsely haired,
untufted, and not markedly elongated or shortened.
Pseudoryzomys icavrini (p. 208)
5. Upper incisors orthodont, proodont or opisthodont, grooved or smooth, zygo-
matic breadth more than distance from posterior tips of nasals to anterior
border of interparietal; interorbital breadth at mid-frontal plane more or less
than greatest width of rostrum; sides of supraorbital region variable, the edges
square, beaded or ridged; width of mesopterygoid fossa variable; plantar sur-
face of heel hirsute, remainder of sole with or without hair; fifth hind toe long,
its tip, less claw, extending to distal end of first phalanx of fourth toe; first
hind toe, less claw, reaching at least to base of first phalanx of second toe; ear
measured from notch, more or less than 70 per cent of hind foot length; tail
variable in length, more or less hirsute, with or without a terminal tuft 6
6. Supraorbital region comparatively broad, the sides diverging from slightly
behind angle of fronto-maxillary suture; interorbital breadth at mid-frontal
plane more than greatest width of rostrum; supraorbital edges square or beaded,
with or without projecting ledges 7
6. Supraorbital region narrow, the sides either parallel or convergent from slightly
behind angle of fronto-maxillary suture to form constriction at approximately
mid-frontal plane; interorbital breadth at mid-frontal plane equal to or, usually,
less than greatest width of rostrum; supraorbital edges square, pinched or,
sometimes, weakly beaded or with projecting ledges 11
7. Size large, greatest length of skull in fully adult more than 30 mm., width of
braincase more than 13 mm., alveolar length of molar row 5 mm. or more,
antero-posterior length of bulla (less tube) more than 5 mm.
Phyllotis griseoflavus (p. 441)
(Also "Graomys edithae" Thomas, p. 461)
7. Size small, greatest length of skull less than 30 mm., width of braincase less
than 13.2 mm., alveolar length of molar row less than 5 mm., antero-posterior
length of bulla (less tube) 5 mm. or less 8
8. Bullae little inflated, their antero-posterior length (less tube) approximately
equal to or less than length of molar row Catomys (p. 123)
(Individuals with extremely worn molars may be confused with species of the
Phyllotis section, hence Calomys is keyed here as well as in the section with
crested molars.)
8. Bullae well inflated, their antero-posterior length (less tube) always more than
length of molar row 9
9. Habitat in western Peru 10
9. Habitat in northern Andes of Argentina Phyllotis hyppgaens (p. 462)
(See also "Graomys edithae" Thomas, p. 461)
10. Ears, from notch, more than 20 mm., hairs of under parts and thighs not
wholly white Phyllotis amicus (p. 438)
10. Ears, from notch, less than 20 mm., hairs of under parts and thighs wholly
white Phyllotis gerbillm (p. 430)
11. Anterior face of each incisor marked by one or two vertical grooves, visible to
the unaided eye 12
1 1 . Anterior face of each upper incisor not grooved though often with fine vertical
striae hardly or not at all perceptible to the unaided eye. ... 14
12. Second upper molar with major and second primary folds extending obliquely
beyond midline of tooth; procingulum reduced (obsolete or absent in worn
tooth), the occlusal surface forming an S-shapea pattern; upper molar row
markedly divergent posteriorly; incisors opisthodont; postero-lateral palatine
excavations deep and greatly enlarged antero-posteriorly . .Euneomya (p. 493)
12. Second upper molar with major and second primary folds not extending be-
yond midline of tooth; major fold in worn tooth more or less at right angles to
midline; outline of occlusal surface of moderately worn tooth more or less
8-shaped, with or without a notch in upper outer corner to mark position of
120 FIELDIANA: ZOOLOGY, VOLUME 46
procingulum ; upper molar row more or less parallel-sided; incisors orthodont
to proodont; postero-lateral palatine excavations not markedly developed . . 13
13. Tail less than 70 mm. and less than 65 per cent of combined head and body
length; hind foot (dry, with claw) less than 25 mm. . .Phyllotis sublimis (p. 419)
13. Tail more than 70 mm. and more than 55 per cent of combined head and body
length; hind foot (dry, with claw) usually more than 25 mm.
Phyllotis pictus (p. 404)
14. Alveolar length of molar row more than 6.6 mm 15
H. Alveolar length of molar row less than 6.6 mm 17
15. Incisors orthodont or slightly opisthodont; second upper molar with procingu-
lum obsolete or absent; primary and major folds of m 3 - penetrating as far as
but not beyond midline of tooth; white of hips and lower sides of rump sepa-
rated by black of outer sides of thighs Chinchillula sahamae (p. 415)
15. Incisors opisthodont; second upper molar with procingulum well developed;
second primary fold of m 2 - penetrating beyond midline of tooth and apex of
major fold; hips, rump and outer sides of thighs more or less uniformly colored
buff to brown 16
16. Medial anterior borders of upper incisors meeting to form a broadly angular
trough when seen in cross section; palatine bones deeply excavated postero-
laterally; cusps of first two upper molars triangular in outline and arranged
in zigzag pattern. Habitat, Andes of Peru, Bolivia and northern Argentina.
Andinomys edax (p. 472)
1 6. Medial borders of upper incisors meeting in midline to form a convex outline
when seen in cross section; palatine bones slightly or not at all excavated
postero-laterally; cusps of first two upper molars elliptical or ovate in outline
with those of outer side nearly or quite opposite their analogues of inner side.
Habitat, Andes of southern Chile and southern Argentina.
Phyllotis micropus (p. 391)
17. Plantar surface of hind foot well haired; skull markedly vaulted mid-dorsally.
Galenomys (p. 464)
1 7. Plantar surface of hind foot bare; dorsal contour of skull flat or slightly convex,
not vaulted 18
18. Prpcingulum of m a reduced or obsolete, of m a obsolete or absent; incisors
opisthodont, their anterior aspects smooth; greatest zygomatic breadth nearly
always less than distance from tips of nasals to posterior borders of last molars;
tail from about 40 per cent shorter to over 25 per cent longer than combined
head and body length 19
1 8. Procingulum of m 2 well developed and persistent except in greatly worn tooth,
of m a present but not always well developed; incisors proodont, orthodont or
opisthodont, with or without vertical striae or weakly defined grooves on ante-
rior aspects; greatest zygomatic breadth more or less than distance from tips
of nasals to posterior border of last molars; tail always shorter than combined
head and body length 20
19. Upper incisors slender, combined width of upper cutting edges less than alveo-
lar length of m 1 ; molar rows parallel-sided or slightly convergent or divergent
posteriorly; lower first molar 4-rooted; zygomata not greatly expanded, tend-
ing to be parallel-sided, their greatest breadth less than distance between
posterior tips of nasals and anterior border of supraoccipital; tail longer or
shorter than combined head and body length.
Phyllotis darwini complex (p. 234)
19. Upper incisors thick, combined width of cutting edges equal to or more than
alveolar length of m 1 ; molar rows usually divergent posteriorly; lower first
molar 3-rooted; zygomata well expanded posteriorly, the sides usually
markedly divergent antero-posteriorly, giving a triangular outline to mid-
cranial region; greatest breadth across zygomatic arches subequal to dis-
tance between posterior tips of nasals and anterior border of supraoccipital;
tail always shorter than combined head and body length.
Phyllotis micropus (p. 391)
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 121
20. Upper incisors ungrooved, opisthodont; tail longer or shorter than combined
head and body length . . 19
20. Upper incisors ungrooved or grooved, proodont or orthodont; tail always
shorter than combined head and body length . .21
21. Tail less than 70 mm. and less than 65 per cent of combined head and body
length; hind foot (dry, with claw) less than 25 mm.; lower first molar 3-rooted.
Phyllotis sublimis (p. 419)
21. Tail more than 70 mm. and more than 55 per cent of combined head and body
length; hind foot (dry, with claw) more or less than 25 mm.; lower molar 3-
or 4-rooted 22
22. Incisors without striae or grooves; width across bullar meati one-half or more
of greatest length of skull; color of upper parts of body pale; prominent ochra-
ceous preauricular tufts present; guard hairs of rump not unusually long or
conspicuously displayed; lower first molar 3-rooted.
Phyllotis boliviensis (p. 410)
22. Incisors with weakly defined striae or grooves; width across bullar meati in
fully adult individual less than one-half of greatest length of skull; upper parts
of body pale; no preauricular tufts; guard hairs of rump unusually long and
prominently displayed; lower first molar 4-rooted. . .Phyllotis pictus (p. 404)
CALOMYS
ZYGODONTOMYS
ELIGMODONTIA
FIG. 27.- Distribution of the genera of the Calomys section of phyllotine
rodents in South America and Panama. For Costa Rican portion of range see map,
fig. 1.
122
CALOMYS SECTION
The characters of the section are given in the key (p. 118). For
its geographic range, see maps (figs. 1 and 27).
Genus CALOMYS Waterhouse
Calomys Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 21 subgenus of
Mus (included species: bimaculatus Waterhouse, type, elegans Waterhouse,
gracilipes Waterhouse). Burmeister, 1854, Thiere Brasiliens, 1: ix, 168
subgenus of Hesperomys, part (species: expulsus Lund, lasiurus Lund).
Thomas, 1884, Proc. Zool. Soc. London, 1884: 449 subgenus of Hespero-
mys, part (species: bimaculatus Waterhouse, type, gracilipes Waterhouse).
Hesperomys Waterhouse, 1839, Zoology Voy. "Beagle," pt. 2, no. 4, p. 75
part (Mus bimaculatus only). Wagner, 1843, Schreber's Saugthiere, Suppl.
3: xii, 510 part (species: bimaculatus Waterhouse, gracilipes Waterhouse,
callosus Rengger, laucha Desmarest). Baird, 1859, Mammals of North
America, p. 453 part (characters, type of tribe Sigmodontes Baird).
Fitzinger, 1867, Sitz. Akad. Wiss. Wien, 56, (1), p. 26 part (species:
callosus Rengger, expulsus Lund). Coues, 1874, Proc. Acad. Nat. Sci.
Philadelphia, p. 177, footnote part (Mus bimaculatus Waterhouse desig-
nated type). Winge, 1888, E Mus. Lundii, 3: 11 (species: simplex Winge
[Pleistocene), molitor Winge [Pleistocene], tener Winge, expulsus Lund).
Thomas, 1888, Proc. Zool. Soc. London, 1888: 133 merged with Cricetus.
J. A. Allen, 1891, Bull. Amer. Mus. Nat. Hist., 3: 291 "no substantial
basis as a generic name." Osgood, 1909, North American Fauna, no. 28,
p. 11 taxonomic history. Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17:
141 (genus ; synonym, Calomys Waterhouse, 1837, preoccupied [!] byCaWo-
mys d'Orbigny and Geoffrey 1830; species: callosus Rengger, carilla Thomas,
ducilla Thomas, expulsus Lund, gracilipes Waterhouse, laucha Desmarest,
lepidus Thomas, sorella Thomas, tener Winge, venustus Thomas). Tate,
1932, Amer. Mus. Nov., no. 541, p. 11 taxonomic history. Ellerman,
1941, Families and genera of living rodents, 2: 445 part (all forms listed
except Paralomys Thomas with Phyllotis gerbillus Thomas). Osgood, 1947,
Jour. Mamm., 28: 168 characters and relationships.
Eligmodontia Thomas, 1896, Proc. Zool. Soc. London, 1896: 1020 part (Calo-
mys Waterhouse and Hesperomys Waterhouse in synonymy).
Necromys Ameghino, 1889, Act. Acad. Nac. Cie'nc., Cordoba, 6: 110, 120
type by monotypy, Necromys conifer Ameghino.
Type species. Mus (Calomys) bimaculatus Waterhouse, by origi-
nal designation (=Calomys laucha Olfers).
123
124 FIELDIANA: ZOOLOGY, VOLUME 46
Included species. Calomys laucha Olfers, sorellus Thomas, lepidus
Thomas, callosus Rengger.
Distribution
Figures 27, 28
Temperate zone grasslands, scrublands, and forest fringes of
South America from the pampas of Argentina north into Paraguay,
Uruguay and southeastern Brazil, west into the Andes of Peru,
Bolivia and the Sierras Pampeanas of Argentina; the genus may be
represented in the Bolivian Chaco and has been accidentally im-
ported into northeastern Venezuela, Curacao and Aruba where it
is now established; altitudinal range from sea level to approximately
5000 meters above.
Characters
External. Small, generally Mus-like in appearance; pelage as a
rule long, thick and smoothly adpressed or moderately lax, upper
parts buff or tawny to drab, under parts white to dark gray; tail
usually shorter than combined head and body length, sometimes
slightly longer, uniformly colored to sharply bicolor, without ter-
minal brush; hind foot (fig. 3) small, first toe less claw not extending
to base of second; fifth toe less claw not extending beyond articula-
tion between first and second phalanges of fourth toe; plantar sur-
face naked, with 6 small tubercles; ears small, their length from
notch never more than hind foot length; postauricular tufts present
or absent; mammae, 6 to 14.
Cranial (figs. 29-32). Skull lightly built; upper surface of fron-
tals usually convex, sometimes flat, with or without a slight median
longitudinal depression; distance across mid-frontal region more or
less than greatest width of rostrum; sides of supraorbital region par-
allel, concave or divergent, with or without beading or overhanging
ledges; outline of fronto-parietal suture usually crescentic, some-
times angular; zygomatic arches little expanded, usually convergent
anteriorly, rarely parallel-sided; anterior border of zygomatic plate
plane or slightly concave; pitted posterolateral palatal depressions
shallow or deep; paired anterior palatal pits situated on maxillaries or
across maxillo-palatal sutures on anterior half of palatal bridge;
width of mesopterygoid fossa at anterior base of pterygoids less than
width of parapterygoid fossa measured at same plane; parapterygoid
fossa shallow or moderately excavated; antero-posterior length of
FIG. 28. Distribution of the species of Colomyv.
126 FIELDIANA: ZOOLOGY, VOLUME 46
bulla (less tube) from slightly more to slightly less than length of
molar row; posterior border of mandibular ramus deeply excised.
Dental (fig. 33). Upper incisors opisthodont to nearly proodont,
ungrooved; molar rows generally parallel-sided; upper first molar
four-rooted, lower three- to four-rooted; m 7 more than one-half to
nearly as long as m^; crown crested, the cusps tuberculate, with an-
terior enamel walls of upper molars slightly more projecting than
posterior enamel walls, and both inclined posteriorly with a slight
inward rotation; principal cusps of outer side arranged in echelon
or in opposition with respect to those of inner; cusps of upper mo-
lars ovate in outline, of lower ovate or tending to become triangular;
anterior fold of m 1 well developed, the procingulum distinctly bi-
lobate in Juvenal with outer conule larger than inner; mesoloph
absent; an inconspicuous mesostyle sometimes present; first primary
fold of m-~- well developed, at least in unworn teeth; second second-
ary fold obsolete in upper molars; first minor fold reduced or absent
in m^, obsolete or absent in m^; major fold of m a sometimes coalesced
with second primary fold; first internal fold sometimes, second in-
ternal fold rarely, discrete in m^; second internal fold of m- 3 - discrete
or coalesced with second primary fold; anterior fold of m T present
at least in unworn tooth; minor fold present in m^ and in unworn
m-s; second primary fold of m^ present, of m^ reduced or obsolete.
Comparisons
Small size, variable number of mammae, unspecialized hind foot,
crested molars and complete absence of mesoloph are salient char-
acters of Calomys. Superficial resemblance between the species of
Calomys, Mus musculus, Phyllotis amicus and Pseudoryzomys wavrini
is dealt with under appropriate species headings. Similarity between
North American Baiomys and the three smaller species of Calomys
(figs. 31-33) appears to be the result of convergence. Baiomys is
practically inseparable from Calomys laucha in size, external and
dental characters, and general shape of skull. It is readily distin-
guished, however, from all South American cricetines except Aporo-
don and Tylomys by its comparatively simple glans penis and
bipartite baculum (cf. p. 58). It is separated from all phyllotines,
including Calomys, by slight dorsal excision of antorbital foramen;
nearly transverse, not markedly anteriorward, orientation of medio-
lateral axis of antorbital bridge; by postero-lateral palatal pits often
wholly or partially concealed from ventral view by paired swellings
on posterior border of bony palate. Characters distinguishing Bai-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 127
omys from Calomys include the hypertrophy into a process of the
burr which marks the origin of the superficialis part of the masse ter
muscle at root of anterior border of zygomatic process; mesopterygoid
fossa always as wide as or wider than parapterygoid fossa measured
at the same plane at anterior base of pterygoid processes; paraptery-
goid fossa shallower; fifth toe of front and hind feet longer, always
extending to base of second phalanx of fourth, or slightly beyond,
and pale postauricular patches absent.
Characters distinguishing Baiomys from Calomys are as trenchant
as any which separate genera and supergeneric groups. Neverthe-
less, their small size and M Ms-like appearance misled Husson (1960)
and Packard (1960) into assuming the existence of a relationship
between Baiomys and Calomys that is much closer than permitted
by the facts. Husson's comparisons of Baiomys with Calomys are
based on individually variable characters discussed below under the
heading Calomys laucha (p. 143). Packard's (1960, p. 664) conclu-
sion "on the basis of internal morphological characters studied (audi-
tory ossicles, hyoid apparatus, and baculum) [that] Baiomys seems
to be more closely related to a South American hesperomine [sic],
perhaps Calomys, than to any North American cricetine" appears to
be baseless. Bacula of Baiomys as figured by Packard (1960, p. 603)
and other authors are fundamentally different from the baculum of
Calomys and all other South American cricetines examined by me
and others (cf. Hooper, 1959, p. 10). Regarding the auditory ossi-
cles, if, as averred by Packard (1960, p. 606), those of Baiomys
"closely resemble" those of Calomys and Thaptomys and "differ
greatly" from those of Zygodontomys, then they must be dismissed
as being devoid of taxonomic value on the generic level. Thaptomys
is not particularly related to Calomys and has nothing to do with
Baiomys while Zygodontomys is a phyllotine very nearly related to
Calomys. As for the hyoid, Packard (1960, p. 603) finds that on the
basis of shape "Baiomys seems to be most closely related to Ochro-
tomys." No comparisons were made with the hyoid of Calomys and
no evidence is presented that the hyoid of this or any other South
American rodent was examined. Packard's corollary (1960, p. 664)
that "pygmy mice were more widely distributed in the past than
they are at present [and that] part of the ancestral stock . . . may
have emigrated from North America into South America in a brief
period in the Pliocene" is entirely without foundation.
There is a striking resemblance between Calomys callosus, Zygo-
dontomys and Phyllotis griseoflavus with respect to their broadly
expanded supraorbital regions (fig. 34).
128 FIELDIANA: ZOOLOGY, VOLUME 46
Variation
In all species color of head, upper parts and sides of body are
Mus-like, under parts white to gray with or without a light buffy
wash. Pale and dark color phases with intermediate stages are found
in all populations. Juvenals, however, are often darker than adults.
The maximum number of mammae noted in Calomys callosus and
C. laucha is 14, but most females of these species show only 8. In
C. sorellus the normal number is 8, but usually only 4 or 6 show.
In C. lepidus there are 8 to 10 mammae, but only 6 may be detect-
able in the dry skin. Pale postauricular tufts are present in all spe-
cies, but not in all individuals of the species. The tail is always
shorter than combined head and body length in lepidus and callosus
and is usually shorter or sometimes as long or slightly longer in
laucha and sorellus. Hind foot is extremely variable in size. Often
an "abnormally" short- or large-footed individual is found in a large
series with which there is agreement in all other characters. The
same is true of other size characters. An extremely large individual
of an older generation than that of other individuals of the same pop-
ulation may appear deceptively like the sole representative of a dis-
tinct species. Conversely, a young, precociously developed individual
with worn molars may be outstanding in a series of older individuals
with normally developed features.
Remarks
The crested, comparatively low-crowned molars of Calomys are
primitive phyllotine characters, but absence of the mesoloph is an
advanced cricetine character. Small size, proportioned ears, vari-
able number of mammae, and terrestrial habits are indications of the
generalized cricetine pattern, but short outer toes and tendency for
reduction of tail are specializations. In general, however, Calomys
appears to be the phyllotine that has departed least from the hypo-
thetical forest-dwelling ancestral stock.
The most generalized member of the genus is Calomys sorellus.
C. laucha is practically indistinguishable but shows more than an
incipient lateral expansion of the supraorbital region. This charac-
ter attains maximum development in Calomys callosus. A parallel
development of the expanded type of supraorbital region has oc-
curred in the nearly related Zygodontomys and the more distant
Phyllotis griseoflavus.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 129
Taxonomic History
Calomys Waterhouse, 1837, is the earliest valid name for rodents
hitherto referred to Hesperomys Waterhouse, 1839, as restricted by
Thomas in 1916. The name Calomys fell into disuse because it was
erroneously believed to be a homonym of Callomys d'Orbigny and
Geoff roy, 1830, a genus of Chinchillidae. However, Article 56 (a) of the
International Code of Zoological Nomenclature states that "even if
the difference between the genus-group names is due to only one
letter, these two names are not to be considered homonyms." Use
of Calomys by Jordan (1888, p. 321) with Hesperomys a synonym, is
as a composite of 5 North American species of cricetines, none of
which was included or is now included in the Calomys of Waterhouse.
Calomys Jordan, therefore, falls as a junior homonym.
Use of the name Hesperomys Waterhouse is one of the most em-
broiled in the taxonomic history of cricetines. It was proposed, in
1839, to contain all American cricetines with the same biserial molar
cusp arrangement seen by Waterhouse in the teeth of the mouse he
described two years earlier as Mus (Calomys) bimaculatus. In addition
to bimaculatus, Waterhouse included in Hesperomys the species
[Peromyscus] leucopus, Symidon [sic= Sigmodon] hispidus, the "spe-
cies of Neotoma," [Oryzomys] galapagoensis, [Phyllotis] xanthopygus
and [Phyllotis] darwini. This broad, essentially supergeneric con-
cept of Hesperomys was revised by Wagner (1843, p. 510) to include
the South American Scapteromys, Oxymycterus, Abrothrix and Calo-
mys, all described by Waterhouse in 1837 as subgenera of Mus.
Wagner, and after him Burmeister (1854, p. ix), continued to em-
ploy Hesperomys as a "supergenus" of South American cricetines.
The literature of purely North American cricetines also became in-
volved with Hesperomys. Baird (1859, p. 453) made it type of
the tribe Sigmodontes (=Cricetinae of modern authors) and referred
10 species, now included in Peromyscus, to the genus Hesperomys.
Still no genotype was designated, but one of the 10 species mentioned,
leucopus, was also included by Waterhouse in the original definition
of Hesperomys. Finally, Coues (1874, p. 177), pointed out that
"Waterhouse, in drawing his comparison between Mus and the New
World mice, took M. rattus and M. bimaculatus for such purpose;
we may properly therefore elect the latter as technically the type."
This statement is the first clear and unequivocal determination of
the status of Hesperomys. The name, therefore, by virtue of its
designated genotype, is an absolute synonym of Calomys Waterhouse.
130 FIELDIANA: ZOOLOGY, VOLUME 46
Hesperomys of Winge (1887, p. 11) is equivalent to Calomys as
defined here, while his Calomys is the Oryzomys of modern literature.
Winge distinguished Hesperomys from his Calomys (= Oryzomys) by
the presence of a well-developed mesoloph in the molars of the latter
and its absence in those of the former. He also observed that the
molars of Hesperomys and Cricetus were similar in this respect.
Thomas (1888, p. 133) went farther and proposed that the name
Hesperomys "be abolished altogether and [its] species united with
the Old-World Hamsters under the name Cricetus." J. A. Allen
(1891, p. 291) also voted for the elimination of Hesperomys as an
invalid name, but he objected to the transfer of its species to Crice-
tus. Thomas (1896, p. 1020) compromised by sinking both Hespero-
mys and Calomys in the synonymy of Eligmodontia Cuvier. This
solution endured until 1916, when Thomas (1916a, p. 141) revived
Hesperomys (instead of Calomys, supposedly invalidated by Cal-
lomys d'Orbigny and I. Geoffrey), as the generic name for lauchas.
FIG. 29. Dorsal and palatal aspects of skulls of a, Calomyx hpidux lepidiis;
b, C. lattcha laucha; c, C. sorellux; d, C. callosus callows. (Enlarged.)
131
FIG. 30. Side view of skull and outer surface of mandible of a, Calomys
lepidus lepidus; b, C. laucha; c, C. sorellus; d, C. callosus callosus. (Enlarged.)
132
1
2
:
O
s
o
5
II
_
11
133
FIG. 32. Palate of a, Baiomys tay-
lori; b, Calomys laucha; c, Calomys
sorellus. (Enlarged.)
134
FIG. 33. Right upper molars and lower left molars of a, Calomys sorellus;
b, C. laucha; c, C. lepiditx; d, Baiomys taylori. (Enlarged.)
135
FIG. 34. Dorsal and palatal aspects of skulls of a, Zygodontomys brevicauda;
b, Calomys callosus; c, Phyllotis griseoflavus. (Enlarged.)
136
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 137
DIAGNOSTIC CHARACTERS AND KEY TO THE
SPECIES OF CALOMYS
1. Borders of supraorbital region of skull divergent from front to back, strongly
beaded and forming broad ledges in fully mature individuals; mid-frontal
width always more than greatest width of rostrum; interparietal usually well
developed antero-posteriorly; greatest length of adult skull at least 24 mm.;
alveolar length of molar row 4.0 mm. or more; head and body length more than
80 mm., tail more than 60 mm callostus
1. Borders of supraorbital region parallel, divergent or slightly concave mid-
frontally, the edges square, never beaded and never forming ledges except,
sometimes, in very old individuals; mid-frontal width more or less than greatest
width of rostrum; interparietal usually narrow antero-posteriorly; greatest
length of skull less than 26.5 mm.; alveolar length of molar row less than 4.3
mm. ; head and body more or less than 80 mm., tail more or less than 60 mm. . . 2
2. Tail less than 50 mm. long, whitish or pale gray; heel and proximal portion of
soles covered with hair, the tarsal tubercle partially hidden from view; sides of
supraorbital region of skull parallel or very slightly concave mid-frontally and
never forming ledges; mid-frontal width less than greatest width of rostrum;
posterior tip of lower incisor indicated as a ridge without capsular projection
on outer side of mandible lepidus
2. Tail more than 30 mm. long, brown above, paler beneath; heel, only, covered
with hair; sides of supraorbital region of skull divergent or parallel, the edges
square or tending to form ledges in old individuals; mid-frontal width more or
less than greatest width of rostrum; posterior tip of lower incisor encased in
projecting capsule 3
3. Supraorbital borders usually parallel or slightly divergent mid-frontally, the
edges never forming ledges; mid-frontal width equal to or less than greatest
width of rostrum; habitat Peru sorelliw
S. Supraorbital borders usually divergent throughout their length except at ex-
treme anterior portions, the edges tending to form ledges in old individuals;
mid-frontal width equal to or more than greatest width of rostrum . . . .laucha
Calomys sorellus Thomas
Eligmodontia sorella Thomas, 1900, Ann. Mag. Nat. Hist., (7), 6: 297. Osgood,
1914, Field Mus. Nat. Hist., Zool. Ser., 10: 166 PERU: La Libertad
(mountains northeast of Otusco).
[Hesperomys] sorella, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: Hi-
classification.
Hesperomys sorella, Pearson, 1957, Breviora, Mus. Comp. Zool., no. 73, p. 1
PERU: Puno (3 miles northeast of Arapa; 5 miles south of Asillo; Hacienda
Calacala, 7 miles southwest of Putina).
Calomys lepidus sorellus, Cabrera, 1961, Rev. Mus. argentino Cienc. Nat.,
"Bernardino Rivadavia," 4: 481 classification.
Hesperomys frida Thomas, 1917, Smithsonian Misc. Coll., 68, no. 4, p. 1
PERU: Cusco (type locality, Chospioc). Thomas, 1920, Proc. U. S. Nat.
Mus., 58: 230, pi. 14, fig. 3 (skull) PERU: Cusco (Huaracondo; Chospioc;
Torontoy; Querefrata; Anta).
Calomys frida frida, Cabrera, 1961, Rev. Mus. argentino Cienc. Nat., "Ber-
nardino Rivadavia," 4: 478 classification.
Hesperomys frida miurus Thomas, 1926, Ann. Mag. Nat. Hist., (9), 17: 314
PERU: Junin (type locality, Yana Mayo, Rfo Tarma). Thomas, 1927,
op. cit., (9), 20: 602 PERU: Paaco (Huariaca; Alcas).
138 FIELDIANA: ZOOLOGY, VOLUME 46
EXPLANATION OF FIGURE 35
Calomys sorellus: collecting localities and collectors.
Type localities in boldface.
Calomys sorellus (1-35)
PERU
1. Huamachuco, 8 miles south, La Libertad. P. O. Simons.
2. Otuzco, mountains northeast of, La Libertad. W. H. Osgood and M. P.
Anderson at 10,000 feet.
3. Macate, Ancash. W. H. Osgood and M. P. Anderson.
4. Tullparaju, Huaraz, Ancash. C. Kalinowski at 4300 meters.
4. Quilcayhuanca, Huaraz, Ancash. C. Kalinowski at 4000 meters.
5. Catac (Hacienda), Ticapampa, Ancash. C. Kalinowski at 3500 meters.
6. Cullcui, Rfo Maranon, Huanuco. J. T. Zimmer at 10,400 feet.
7. Huanuco Viejo, Huanuco. J. T. Zimmer at 12,700 feet.
8. Panao Mountains, Huanuco. J. T. Zimmer at 10,300 feet.
9. Huanuco, Huanuco. J. T. Zimmer at 12,200 feet.
10. Alcas, Huariaca, Pasco. R. W. Hendee at 11,500 feet.
10. Huariaca, Pasco. R. W. Hendee at 9000 feet.
11. La Quinua, Pasco. E. Heller at 11,600 feet.
12. Carhuamayo, Junfn. C. C. Sanborn at 14,500 feet.
13. La Oroya, Junm. M. P. Anderson at 12,000 feet.
14. Yana Mayo, Rio Tarma, Junin. Type locality of miurus; R. W.
Hendee at 8500 feet.
15. Piso (Hacienda), Locroja, Huancavelica. C. Kalinowski.
16. Mayoc, Locrojo, Huancavelica. C. Kalinowski.
17. Huancavelica, Huancavelica.- C. Kalinowski at 3680 meters; A. R. G.
Morrison at 12,000 feet.
18. Lircay, Huancavelica. C. Kalinowski at 3310 meters.
19. Tambo, San Miguel, Ayacucho. C. Kalinowski.
20. Huanta, Ayacucho. C. Kalinowski.
21. Puente Pajonal, Ocros, Ayacucho. C. Kalinowski at 1900 meters; includes
Hacienda Pajonal, 1900 meters.
22. Ocros, Ayacucho. C. Kalinowski at 3150 meters.
23. Andahuaylas, Apurimac. C. Kalinowski; locality includes Hacienda Mo-
zabamba, 2300 meters; Hacienda Palmar, 2200 meters; Uripa, 3100 meters;
Hacienda La Laguna, 3040 meters.
24. Quebrada Matara, Apurimac. C. C. Sanborn; includes Hacienda La Vic-
toria, 7000 feet; Hacienda Matara, 6200 feet.
25. Chirapata, Cosireni Pass, Cuzco. E. Heller.
26. Torontoy, Cuzco. E. Heller at 12,000 feet.
27. Chospioc, Cuzco. Type locality of frida; E. Heller at 10,000 feet.
28. Huaracondo, Cuzco. E. Heller at 10,850 feet.
29. Anta, Cuzco. O. Garlepp.
30. Urco (Hacienda), near Calca. J. M. Schmidt at 9500-10,000 feet.
31. Cuzco, Cuzco. C. C. Sanborn.
32. Querefrata, Cuzco. Not located; E. Heller.
33. Arapa, 3 miles northeast, Puno. O. P. Pearson at 12,600 feet.
34. Asillo, 5 miles south, Puno. O. P. Pearson at 13,000 feet.
35. Calacala (Hacienda), 7 miles southwest of Putina. O. P. Pearson at
13,000 feet.
FIG. 35. -Collecting localities of Calomyx sorcllm. See opposite page for
explanation.
139
140 FIELDIANA: ZOOLOGY, VOLUME 46
Type. Female, British Museum (Natural History) no. 0.6.6.29;
collected November 28, 1899, by Perry 0. Simons.
Type locality. Eight miles south of Huamachuco, La Libertad,
Peru; altitude, 3500 meters above sea level.
Distribution (fig. 35). Peruvian Andes from the department of
La Libertad southward into Cusco and Puno. Altitudinal range
from approximately 2000 to 4600 meters above sea level.
Characters. Larger of the two known Peruvian species of Calo-
mys; pelage long, soft, moderately lax, underfur thick; tail from
approximately 60 per cent to fully as long as head and body com-
bined, exceptionally slightly longer; tail bicolor except, often, at
extreme tip; fifth hind toe long but not extending beyond articula-
tion between first and second phalanges of fourth toe; white or buffy
postauricular tufts present but not always conspicuous; upper parts
of body ochraceous to tawny mixed with black; a more or less de-
fined, sometimes broken, ochraceous lateral line present; tip of muzzle
usually ochraceous; under parts gray, rarely with a weak buffy wash;
mammae normally 8, but usually only 4 or 6 detectable in dry skin ;
borders of supraorbital region of skull (figs. 29, 30, 36) slightly di-
vergent, the edges square, never beaded; mid-frontal width about
equal to or, usually, less than greatest width of rostrum; inter-
parietal extremely reduced antero-posteriorly; other external and
cranial characters as given in the key (p. 137); dental characters
(figs. 32, 33) as for the genus.
Comparisons. Calomys sorellus is distinguished from the allo-
patric C. laucha chiefly by larger average size, fifth hind toe slightly
longer, sides of supraorbital region less divergent, their edges less
sharply squared. Comparison with the partially sympatric C. lepidus
is made elsewhere (p. 160). The superficial resemblance between
C. sorellus and Phyllotis amicus is restricted to character of pelage,
color, and small body size.
Variation. A tawny and a dark, or olivaceous, phase are pres-
ent in most series. Individuals may molt from one phase to the
other. The molt cycle is individual rather than seasonal in present
material. A gradient or other pattern of geographic variation in
color or size is not evident.
Taxonomy. Specimens from northeast of Otuzco, La Libertad,
here regarded as most nearly representing the type of sorellus
Thomas, were identified as such by Osgood (supra cit.). Evidently
this species was overlooked by Thomas when he described one of
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 141
FIG. 36. Calomys sorellus. Dorsal and ventral aspects of skulls of two adults
from Lircay, Peru. (X 2.)
its representatives from southern Peru under the new name Hes-
peromys frida. It was compared with Phyllotis, and some differences
between Calotnys frida and callosus ("//. venustus") were noted.
Calomys sorellus was again ignored when Thomas erected Hespe-
roniys frida miurus. This was characterized as shorter-tailed than
typical frida. Tail measurements of miurus and frida are given
below, following their respective combined head and body meas-
urements:
142 FIELDIANA. ZOOLOGY, VOLUME 46
miurus: head and body, 86; tail, 76; tails of additional specimens,
70-80 mm.
frida: head and body, 102; tail, 91; tails of additional specimens,
82, 85, 85, 87 mm.
The measurements reveal that the tail of the type of miurus
is approximately 47 per cent of total length and that of frida is
also about 47 per cent of total length. Furthermore, the tail length
of miurus is approximately average for the series to which it belongs,
while that of the type of frida is extremely long.
Habits and habitat. The two specimens recorded by Osgood
from the northern Peruvian Andes northeast of Otuzco, at 11,000
feet above sea level, "were caught in tall grass and weeds growing
about the base of rough limestone exposures on the very top of the
mountains." This is all that is known of the life history of Calomys
sorellus.
Measurements. See Table 2 (p. 189) .
Specimens examined. 130, all in collection of Chicago Natural
History Museum. PERU. La Libertad: Otuzco, 2. Ancash: Macate,
1; Hacienda Catac, Ticapampa, Tullparaju, Huaraz, 2; Quilcay-
huanca, Huaraz, 2. Huanuco: "Panao Mountains," 3; Huanuco, 8;
Huanuco Viejo, 1; Cullcui, Rio Maranon, 1. Pasco: Quinua, 9.
Junin: Yana Mayo, 1; Oroya, 2; Carhuamayo, 1. Huancavelica:
Hacienda Piso, Locroja, 3; Mayoc, Locroja, 1; Huancavelica, 15:
Lircay, 11. Ayacucho: Tambo, San Miguel, 10; Huanta, 4; Ocros, 4;
Puente Pajonal, Ocros, 3. Apurimac: Andahuaylas, 16; Quebrada
Matara, 9. Cusco: Chirapata, Cosireni Pass, 1; Hacienda Urco,
near Calca, 15; Cusco, 5.
Calomys laucha Olfers. (Synonymy under subspecies.)
Distribution (maps, figures 28 and 37). Grasslands and scrub-
lands in southern Minas Geraes, south through the Brazilian coastal
states into Paraguay, Uruguay and the Sierras Pampeanas and
plains of Argentina as far as the Rio Negro; west to the Andean
foothills of extreme southern Bolivia; established as import colonies
in Monagas, Venezuela, and the Netherlands West Indian islands
of Curacao and Aruba; altitudinal range from sea level to approxi-
mately 2500 meters above.
Characters. Smallest phyllotine within its geographic range; pel-
age long, thick, smoothly adpressed; tail from approximately 35
per cent to 108 per cent of combined head and body length, brownish
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 14:1
above, beneath paler but never sharply defined white; fifth hind toe,
less claw, not extending to tip of first phalanx of fourth toe (fig. 38);
pale buff to white postauricular patches usually present; upper parts
of body buff to tawny finely mixed with black; an ochraceous lateral
line often present; under parts of body from sharply defined white
to moderately well-defined grayish with or without an ochraceous
wash, base of hairs of belly and chest slaty; mammae from 8 to 14;
borders of supraorbital region of skull (figs. 29-31) divergent, the
edges square, never beaded; mid-frontal width equal to or more
than greatest width of rostrum; interparietal usually narrow antero-
posteriorly. Other external and cranial characters as given in the
key (p. 137) ; dental characters (figs. 32, 33) as for the genus.
Comparisons. Remarkable resemblances between the non-
phyllotine Baiomys and Calomys laucha have been discussed under
the generic heading (p. 127 and figs. 31, 32). Characters used by
Husson (1960, p. 38) for distinguishing the two genera are variable
and confused. This author compared his six specimens of "Baiomys"
hummelincki ( = Calomys laucha) with four of the same species from
Argentina, one specimen of C. lepidus from Peru, two of Baiomys
taylori from Texas and four of B. musculus from Mexico. He con-
cluded that Baiomys differed from Calomys laucha by its smaller,
more rounded m-, with major fold obsolete or absent, and by
the shape of its interparietal, which was said to be broader antero-
posteriorly and shorter transversely, extending only about one-half
the distance across the braincase. In the approximately 100 Chicago
Natural History Museum specimens of Baiomys represented by B.
taylori and B. musculus, m^ is often, if not usually, smaller and
more rounded in outline than in most comparable specimens of
Calomys laucha. The third molar of the latter, however, is so variable
in size and shape that all conditions found in Baiomys are frequently
duplicated in Calomys. Unworn m^ of Calomys laucha is usually
indistinguishable from worn or unworn m a of Baiomys. The major
fold is usually open to the margin in Calomys but sometimes appears
only as an enamel island, quite as in "Baiomys" hummelincki. In
Baiomys musculus the major fold is usually an enamel island, the
marginal flexure being obsolete or absent. In contrast, the major
fold of m : ' in B. taylori is open at the margin in nearly all but
the most worn teeth. Packard's (1960, p. 586) figures of the enamel
pattern of the molars of Baiomys are not clear on this matter. His
figure of m :i in B. taylori lacks the marginal flexure or any other indi-
cation of the presence of the major fold, while that of B. tnusculux
shows a weak marginal flexure. Variation in the structure of the
O 1
co o
CO
O
{3
WD
1
s
O5
5>
c
J
ts
3
w 8 w
C i-I
J (-1
. a
"S
"So to
*S *^ d)
1 J
M - 3 ^S
= p i
s i ^
3 U
pq ^
H ^
s c S
^ p*i
' ^
a; ^ c2
| S 3
w pi
10 .- "O , O i
13 1 ' ^
i
4J O T3 . C
J 1 \^ ^
^ nJ
JURE 37
rs. Type localities in boldface.
Chumbicha, Catamarca (415 meters).-
meters.
Goya, Corrientes.^ R. Perrens.
Yacanto, near Villa Dolores, Cordoba.-
1000 meters.
Canada Honda, San Juan.^ E. Budin a
Buenos Aires, Buenos Aires.
La Plata, Buenos Aires.^ O. Thomas.
Ensenada, Buenos Aires.- C. Spegazzin
San Miguel, Buenos Aires. J. Crespo.
Henderson, Buenos Aires.^ W. H. Osgo
Torrecito, Buenos Aires.^ W. H. Osgooi
Los Inglesas, Buenos Aires. H. E. Box
Dorrego (=Coronel Dorrego), 10 km.
Aires (113 meters). C. C. Sanborn.
RoUfo m. ,,.., i},,,,,,,... AI',. Q O n TV,
Algarrobo, Buenos Aires (47 meters). J
Pichi Mahuida, La Pampa (119 meters)
meters.
Chimpay, Rfo Negro (170 meters). C.
Choele-Choel, Rio Negro. E. Budin.
:ERLANDS WEST INDIES (35-36)
/-l A T) -0:4.4.. .. T> 1ir~
lection.
Aruba.^ P. Wagenaar Hummelinck; A.
ZUELA (37)
Maturin, 42 km. south, Monagas. B. B
v ~ / o
K
W
Qti O5 O i 1
coco^f-'tfiocot 0005 c
> i i eg CO T(< EH u
ZD X^ C~
^ 1-1 eg (M
eg eg eg eg eg eg eg eg eg c
5 co co co co y c
o co fq co
O 1
^
>
Z ^
O as
d
1
o OT -
S
d o
OS ^
^ ?
^ o
? us a>
<3 '-
Z |
i
C 02
3 $
1
I * s|
2 J s
PH M
O
c
^ ,-;
c <
1
> C ^
3 1 ? m .
x .s s
o ^
CO
pq *
W |
f- VI
4J CO -U CO
W ^
2 W "* 1.
p~* 05 i-^*
0) t-> O cS
2 *
4 TJ pj
^-x * CO
C ^ C C
fe s
c7 fi
i S *
" "S TJ S
s s .
- - -JS '
to a) f
fe
s s s
3 1 i 1
c
fe
i 1 3 i
3 1 V 2
H P CO C
2 3 1-2
: ^> as
i
3i ^ ^**
i -e 05 e
R
<O . S
O "2 ^D O 53
Si J ^ "*
-u O 4j | !
cs Tf c d
<-> -U. ^ ^ 1
.S rt = JO {
3 .5 ^ S3 ^ "
SI fig ^
1. N S*"
5 C tM s
3 o) .(Me
3 o C ^ =
J oo -^ a E-
? C - 3 C a
5 -g ^ PQ ^ ^
5 S -| H
5 H 1
| C F^H v.
* 9 7
r 1 1 S
i 1 I'l
, EH
^ PH
99 _
>s ,2 -2
^ _f* *^ tt
O S W (j
U 8 * <5 S
: ( fe 6 > =
S . ^ u 8 1 . - <3 .J
. . _^ ,,-wJ
o O ^ T >> i H.
rf ^^ "^ CO ^ 1 i
2 co c .2, 1. 1
3 . 1 W 3 >> v -
* a 3 S3
' i^- 1
^ e^
EH'C | "^e-rt JlJ 03 ^
J O ~ _2 t ~ 5 .^ s
(J2; ^ ^C5 ja
eg ci o
T -3 H . ^ 1 . : i S {
?! J^I^J
; Jl "S 'S '+3
5 S ^ C
_j "O "C
'"^ .2 2
2. " ^utec'3 s^Xs
J-si gllll 1-1
s o c 2
3 2 G -g .g .5 3 _n
^) w ^^ w n .
i u< ^ /^ C
O Og o ce
~
- E-" CQ rh O O <! <3 &PnP
H O! S H-s E-
N !
^ ^ O
H
O
ffi
144
B
145
146
FIELDIANA: ZOOLOGY, VOLUME 46
FIG. 38.' Calomys laucha. Head, fore and hind feet of specimen preserved
in alcohol. Copied from the original drawings of Baiomys hummelincki Husson
(I960, fig. 7).
third molar in cricetines in general and its significance in dental
evolution is discussed elsewhere (p. 100). Regarding Husson's inter-
parietal character, the bone extends nearly or quite across the width
of the two parietals combined in Calomys laucha including three
skulls at hand of the original series of "Baiomys" hummelincki,
and in Baiomys musculus. In B. taylori the interparietal usually ex-
tends only two-thirds the distance, sometimes the full distance,
across both interparietals.
The introduced M us musculus, often found together with Calomys
in houses and surrounding grounds, is also similar in superficial
characters and in general outline of skull. Mus and Calomys also
agree in size, relative length of tail, limb proportions and number
of mammae. In Mus musculus, however, pelage is comparatively
shorter, thinner and usually unctuous; under parts darker, washed
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 147
with ochraceous and little or not at all defined from sides; lateral
line absent; tail often monocolor; hairs of upper surface of hands
and feet dark; post-auricular patches absent. Differences between
Mus and Calomys in details of cranial structure and enamel pattern
of molars are obvious and need not be discussed here.
Nearest Calomys laucha is the allopatric C. sorellus, known only
from Peru. Proper appraisal of the slight differences between the
two cannot be made without knowledge of whether or not either
or both forms occur in the intervening highlands of Bolivia.
Where Calomys laucha and C. callosus are found together the
latter is larger throughout, with distinctive cranial characters. Very
old individuals of C. laucha, however, approach and may equal in
size young adults of C. callosus. In these cases, the alveolar length
of the molar row of the first species is less than that of the second.
Variation. Size differences between adults of any one population
are more remarkable than average size differences between popu-
lations. Evidently lauchas attain maturity within a few weeks after
birth, but their growth continues throughout a life span of months
and, potentially if not actually, of years. Old pelage is more gray
than new and molt seems to follow a seasonal pattern, as shown by
the following specimens from Uruguay and eastern Argentina.
No. of Condition
specimens Locality Date of pelage
2 Minas, Uruguay Nov. 21-23 molting
Algarrobo, Buenos Aires Jan., 1926 worn
7 Near Dorrego, Buenos Aires April 2-3, 1940 molting
7 Chimpay, Rfo Negro April 6-7, 1940 molting
2 Choele-Choel, Rfo Negro May, 1928 new
12 Torrecita, Buenos Aires May 30-June2, 1923 new
It appears that old pelage coincides with summer, new pelage
with winter; spring and fall are molt periods.
Geographic variation, if present in the species, is masked in
present material by individual variation in size, age differences,
and seasonal differences in color and pelage.
Habits and habitat. The laucha is the common pampa mouse.
Its name is the one applied by natives to any small rodent and
Azara adopted it for Calomys for want of another. The laucha
lives in grass clumps, among cacti, in piles of rock, rubbish, weeds,
and faggots, and in and about houses. Charles Darwin (in Water-
house, 1839, p. 44) noted that the peasant who brought him the
type of Calomys bimaculatus found six of the same species "living
together in one burrow." On the other hand, Oldfield Thomas
148 FIELDIANA: ZOOLOGY, VOLUME 46
(1916b, p. 184) made other observations during his collecting trip
into the La Plata region in 1896. "This animal [i.e., Hesperomys
rnurillus, which Thomas thought was different from true H. laucha]
is not much of a burrower, but lives about in the grass, and ex-
amples may be easily obtained by kicking up loose heaps of hay,
thistle stalks, or other rubbish, under which the mice take refuge.
One specimen I have marked as found under a heap of thistle-stalks,
in a round nest, the size of a tennis ball, made of thistle-down.
Another was dug up, semi-torpid, in very cold weather, from about
6 inches below the surface of the ground." On an earlier occasion,
Thomas (1898b, p. 3) recorded the same mice as Oryzomys laucha
and remarked that in the city of La Plata, the species "inhabits
the Museum park and the fields round the town and a specimen
or two may generally be kicked out from under heaps of weeds
or faggots left lying about the houses. Adult specimens are how-
ever by no means easy to obtain, and the great majority of those
I saw and trapped were little more than half grown." Henry Durnford
(in Thomas, 1898a, p. 211) noted that the laucha he collected in
Chubut "makes a nest in a thick bush about a foot above the ground.
The nest is made of grass torn into fine fragments." This information
fits, rather, the scansorial Eligmodontia taken by Durnford at the
same time.
A female Calomys laucha in captivity was studied by the Argen-
tine epidemiologist Dr. J. M. de la Barrera (1936, p. 474). Mated
July 30, 1935, the mouse produced a litter of 5 young on the 13th
of September! Mated again October 2, 1935, it produced 3 young
on the 26th of the same month. The last birth indicates a gestation
period of approximately 25 days. This is normal for a small cricetine.
The first litter, however, could not have required a gestation period
of 43 days, as indicated by the dates. It is practically certain that
there were two matings in this period, with offspring, if any, of the
first destroyed by one or both parents; de la Barrera speaks of
the female as being voracious and cannibalistic.
Nothing is known of the habits and circumstances of the impor-
tation of the Curacao and Aruba lauchas described as Baiomys
hummelincki by Husson in 1960. The type was collected in 1947.
Other specimens examined by Husson date from 1930 (Aruba, P.
Wagenaar Hummelinck, collector) to 1959 (Curacao, J. H. Stock,
collector). Presence of the species in the Netherlands West Indies
was first reported in 1940 by Hummelinck (1940, p. 69) under the
name Hesperomys sp.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 149
The following account of the Venezuelan import colony is quoted
from Butterworth (1960, p. 517):
"During the summer of 1958, Arnold Menke, Stephen Bromley
and I made collections of animals in northeastern Venezuela for
the Los Angeles County Museum. The facilities of the United
Geophysical Corporation were made available to us, and part of
our collecting was conducted from a temporary headquarters camp
located 42 km. southeast of Maturin in the State of Monagas. Thir-
teen specimens of Calomys laucha were collected in the immediate
area of the camp. . . . The present extension of the known range
is possibly due to artificial introduction and establishment in the
northern part of Venezuela. Units of the United Geophysical Com-
pany are also located in Bolivia, and equipment is frequently shipped
back and forth between camps. It is possible that these mice were
transported in equipment and subsequently became established in
Venezuela.
"These short-tailed mice were timid creatures and seldom tried
to escape when uncovered. All were collected by hand and, although
they bite if molested, only one of them made an attempt to bite and
escape. Four animals were found hiding under trash or boards in
the camp area. Six had taken up residence in hollow logs and were
found as far as 1000 feet from the camp in an adjacent marshy
meadow.
"Of the thirteen specimens collected, nine were adults and
four were juveniles. Five adult males had scrotal testes averag-
ing 10 x 5 x 4 mm. All four adult females were pregnant. Three
contained four embryos or fetuses ranging from 4 to 20 mm. (crown-
rump); one female contained three fetuses measuring 12 mm.
"A nest containing three recently born young was uncovered
under a board in the camp area. The nest was a shallow depression
in the ground, lined with fine grasses. The mother stood over
the young which lay on their backs while nursing. The hairless
young measured approximately 36 mm. (total length) and had tightly
closed eyes and ears. The mother later deserted the nest and the
young were preserved in formalin."
Calomys laucha laucha Olfers
Rat septicme on rat laucha Azara, 1801, Quadruples du Paraguay, 2: 102.
Laucha Azara, 1802, Apuntamientos par la historia natural de los quadrupedos
del Paraguay y Rfo de La Plata, 2: 96. Azara, 1809, Voyage Ame>ique
Mend., 1: 333.
150 FIELDIANA: ZOOLOGY, VOLUME 46
[Mus?] laucha Illiger, 1815, Abh. Akad. Wiss. Berlin, 1804-1811: 108
nomen nudum.
Af[z<s] laucha Olfers, 1818, in Eschwege, Journal von Brasilien, Neue Biblio-
thek der Reisebeschreibungen zur Erweiterung der Erd- und Wolkerkundc,
Weimar, 15, (2): 209 PARAGUAY: name based on Azara's laucha.
Brants, 1827, Het geschlacht des Muizen, p. 148 laucha Azara.
Mus laucha, Desmarest, 1819, Nouv. Diet. Hist. Nat., 29: 65 rat septieme ou
rat laucha Azara. Desmarest, 1822, Mammalogie, 2: 306.
H[esperomys] Laucha, Wagner, 1843, Schreber's Saugthiere, Suppl. 3: 543
classification.
[Hesperomys] laucha, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification. Tate, 1932, Novit. Amer. Mus. Nat. Hist., no. 557, pp. 4, 5
taxonomic history.
Hesperomys laucha, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 182
ARGENTINA: Corrientes (Goya) . Marelli,1924,ElencoSist. Fauna Prov.
Buenos Aires, p. 671 ARGENTINA: Buenos Aires; Tucumdn. Husson,
1960, Studies on the fauna of Curagao and other Caribbean Islands, 10,
(43): 38 ARGENTINA: Corrientes (Goya); Tucumdn (Concepcion);
comparisons.
Oryzomys laucha, Thomas, 1897, Ann. Mag. Nat. Hist., (6), 20: 215 (in text)
PARAGUAY: (type locality); ARGENTINA: Buenos Aires (Bahia
Blanca; Tala; La Plata); Salta (along Rio Parana to mouth). Thomas,
1898, Bol. Mus. Zool. Anat. Comp. Torino, 13: 3 PARAGUAY: Chaco
(Aguairenda) ; ARGENTINA: Salta; Corrientes (Goya); Buenos Aires
(Tala; Buenos Aires; La Plata).
[Eligmodontia] laucha, Trouessart, 1904, Cat. Mamm., Suppl., p. 428 classi-
fication.
Eligmodontia laucha, Thomas, 1910, Ann. Mag. Nat. Hist., (8), 5: 242
ARGENTINA: Buenos Aires (Los Inglesas).
Calomys laucha laucha, Hershkovitz, 1959, Jour. Mammal., 40: 339 Azara's
laucha; bimaculatus Waterhouse a synonym. Vaz Ferreira, 1960, Arch.
Soc. Biol. Montevido, 24: 67, fig. 1 (ears), figs. 2-5 (skull) URUGUAY:
Artigas (Salto; Tacuarembo); characters; habits.
Calomys laucha, Butterworth, 1960, Jour. Mammal., 41: 517 VENEZUELA:
Monagas (42 km. southeast of Maturfn); habits.
Mus bimaculatus Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 18
URUGUAY: Maldonado (type locality, Maldonado). Waterhouse, 1839,
Zool. Voy. "Beagle," pt. 2, pp. 42, 43, pi. 12 (animal), pi. 34, fig. 3 (skull,
dentition) description. Coues, 1874, Proc. Acad. Nat. Sci. Philadelphia,
p. 177, footnote part, type of Hesperomys Waterhouse by selection.
Coues, 1877, Monogr. N. A. Rodentia, 1: 44 type of Hesperomys Water-
house.
Mus (Calomys) bimaculatus, Waterhouse, 1837, Proc. Zool. Soc. London,
1837: 21.
Eligmodontia bimaculatus, Lesson, 1842, Nouv. Tabl. Reg. Anim., p. 133.
Hesperomys bimaculatus, Burmeister, 1861, Reise La Plata Staaten, 2: 415
ARGENTINA: Parana; Tucumdn; may be Azara's laucha. Figueira,
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 151
1894, An. Mus. Nac. Montevideo, 2: 17 (separate) URUGUAY: through-
out the country. Thomas, 1927, Ann. Mag. Nat. Hist., (9), 19: 550 -
designation of lectotype and lectoparatype. Sanborn, 1929, Field Mus.
Nat. Hist., Zool. Ser., 17: 157 URUGUAY: Minas (Paso de las Averias,
Rfo Cebollati; Polanco). Devincenzi, 1935, An. Mus. Hist. Nat. Monte-
video, (2), 4: 60 URUGUAY. Marelli, 1924, Elenco Sist. Fauna Prov.
Buenos Aires, p. 671 ARGENTINA. Crespo, 1944, Rev. Argentina
Zoogeogr., 4: 138 ARGENTINA: Buenos Aires (San Miguel).
H[esperomys] bimaculatus, Burmeister, 1869, An. Mus. Publ. Buenos Aires,
1: 457 laucha Azara. Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification; type of Hesperomys.
Hesperomys bimaculatus, Burmeister, 1879, Descr. Phys. Rep. Argentine, 3:
224 ARGENTINA: eastern half of country; Mus gracilipes Waterhouse
a young individual of bimaculatus.
H[esperomys (Calomys)] bimaculatus, Thomas, 1884, Proc. Zool. Soc. London,
1884: 449, 454, pi. 44, fig. 14 (ear) classification and measurements of
type.
[Hesperomys} bimaculatus, Osgood, 1933, Field Mus. Nat. Hist., Zool. Ser.,
20: 14 URUGUAY: Minas (Polanco; Rfo Cebollati).
Calomys dubius bimaculatus, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 477 classification.
Mus gracilipes Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 19 AR-
GENTINA: Buenos Aires (type locality, Bahfa Blanca). Waterhouse,
1839, Zool. Voy. "Beagle," pt. 2, pp. 42-45, pi. 11 (animal), pi. 34, fig. 4
(skull, dentition, hind foot) description.
Mus (Calomys) gracilipes, Waterhouse, 1837, Proc. Zool. Soc. London, 1837:
21 classification.
Eligmodontia gracilipes, Lesson, 1842, Nouv. Tabl. Regn. Anim., p. 133.
Thomas, 1898, Proc. Zool. Soc. London, 1898: 211. Allen, 1905, Exped.
Patagonia, Princeton Univ., Mamm., p. 54 ARGENTINA.
[Hesperomys (Calomys) laucha] gracilipes, Trouessart, 1881, Bull. Soc. Etud.
Scient., Angers, 1880, 10, (1); 138 classification.
H[esperomys (Calomys)] gracilipes, Thomas, 1884, Proc. Zool. Soc. London,
1884: 449 classification.
[Hesperomys] gracilipes, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
Mus pusillus Philippi, 1858, Arch. Naturg., (24), 1: 79 CHILE: Valparaiao
(type locality said to be the coastal region near Valparaiso). Philippi,
1900, Anal. Mus. Nac. Chile, Zool. Entr., 14a: 19, pi. 5, fig. 2 type re-
described; regarded as conspecific with the laucha [ = Calomys laucha}.
Osgood, 1943, Field Mus. Nat. Hist., Zool. Ser., 30: 239 type rede-
scribed; regarded as non-Chilean and probably an Argentine Hesperomys
[ = Calomys}.
[Hesperomys (Akodon)] pusillus, Trouessart, 1881, Bull. Soc. Etud. Scient..
Angers, 1880, 10, (1): 142 classification.
[Akodon] pusillus, Trouessart, 1897, Cat. Mamm., p. 538 classification.
152 FIELDIANA: ZOOLOGY, VOLUME 46
Akodon pusillus, Gyldenstolpe, 1932, Kiingl. Sv. Vet. Akad. Handl., 11, (3):
101 classification.
Eligmodontia laucha musculina, Thomas 1913, Ann. Mag. Nat. Hist., (8), 11:
138 ARGENTINA: Jujuy (type locality, Maimara, 2230 meters alti-
tude).
[Hesperomys laucha] musculinus, Thomas, 1916, Ann. Mag. Nat. Hist., (8),
17: 141 classification.
H[esperomys] musculinus, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 183
comparisons; 6 or 7 pairs of mammae.
Hesperomys musculinus, Thomas, 1920, Ann. Mag. Nat. Hist., (9), 6: 116
ARGENTINA: Catamarca (La Puntilla, near Tinogasta). Thomas, 1926,
op. cit., (9), 18: 194 ARGENTINA: Jujuy (Santa Catalina).
Calomys laucha musculinus, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 479 classification; cortensis Thomas a syno-
nym.
Hesperomys musculinus cortensis Thomas, 1920, Ann. Mag. Nat. Hist., (9),
5: 190 ARGENTINA: Jujuy (type locality, Jujuy, 1258 meters altitude).
Hesperomys murillus Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 183
ARGENTINA: Buenos Aires (type locality, La Plata; Las Talas; En-
senada; Bahfa Blanca).
Hesperomys murillus murillus, Yepes, 1935, Rev. Inst. Bacteriol., Buenos
Aires, 7: 227, pi. 6, fig. 2 (animal) ARGENTINA: Buenos Aires;
Cordoba.
Hesperomys murillus cordovensis Thomas, 1916, Ann. Mag. Nat. Hist., (8),
17: 184 ARGENTINA: Cordoba (type locality, Yacanto, near Villa
Dolores, 900 meters altitude). Thomas, 1919, op. cit., (9), 3: 115
ARGENTINA: Catamarca (Chumbicha). Thomas, 1920, op. cit., (9),
6: 116 ARGENTINA: Catamarca (La Puntilla, near Tinogasta).
Thomas, 1921, op. cit., (9), 8: 216 ARGENTINA: San Juan (Canada
Honda, 50 km. south of San Juan). Thomas, 1926, op. cit., (9), 17:
322 BOLIVIA: Tarija (Tablada; Sama). Thomas, 1926, op. cit., (9),
17: 604 ARGENTINA: Tucumdn (Norco). Thomas, 1927, op. cit.,
(9), 20: 204 ARGENTINA: La Pampa (Pichi Mahuida).
H[esperomys] murillus cordobensis [sic], Yepes, 1935, Rev. Inst. Bacteriol.,
7: 227 ARGENTINA: Neuquen.
Calomys laucha cordovensis, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 478 classification.
Hesperomys bimaculatus bonariensis Osgood, 1933, Field Mus. Nat. Hist.,
Zool. Ser., 20: 14 ARGENTINA: Buenos Aires (type locality, Torre-
cita). Sanborn, 1947, Fieldiana, Zool., 32: 242 type history.
Calomys dubius bonariensis, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 477 classification.
Baiomys hummelincki Husson, 1960, Studies on the fauna of Curajao and
other Caribbean Islands, 10, (43): 34, fig. 7 (head, feet), pi. 6 (skull),
pi. 7 (skull, molars) NETHERLANDS ANTILLES: Curacao (type
locality, Klein Santa Martha; Plantation Jongbloed; Savonet Cave;
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 153
Sheribana); Aritba (Dakota Airport, Boca Morto; Barranca Corra; Seroe
Blanco). Husson, 1960, De zoogdieren van de Nederlandse Antillen,
pp. 86, 157, fig. 21a (incisors), 22 (head, feet), pi. 26 (skull), pi. 306 (upper
molars) characters.
Hesperomys sp., Hummelinck, 1940, Studies on the fauna of Curacao, Aruba,
Bonaire and the Venezuelan Islands, The Hague, 1: 69- NETHER-
LANDS WEST INDIES: Aruba (Vadar Piet near Fontain); determina-
tion by M. A. C. Hinton and R. W. Hayman.
Calomys dubius dubins, Cabrera (part, not Fischer), 1961, Rev. Mus. argen-
tine Cienc. Nat. "Bernardino Rivadavia," 4: 477 citation of "//c.spm>-
mys bimacitlatHS bimaculatus Yepes, Rev. Inst. Bacteriol., 7: 1935: 227"
only.
Type, None preserved; technical name based on Azara's pub-
lished description of three specimens.
Type locality. One of Azara's specimens was taken in a pile of
maize stalks on a farm in the province of "Buenos Aires," and a
second in the "pampas" about 25 S. Lat. Buenos Aires in Azara's
time included present-day Uruguay and the Argentine provinces of
Misiones, Corrientes and Entre Rios. Azara did no work in the
modern province of Buenos Aires. The second locality, at the
twenty-fifth parallel, may be construed as being in the neighbor-
hood of Asuncion, Paraguay, to which area the type locality is now
restricted. Paraguay was selected by first reviser Olfers as type
locality.
Distribution (fig. 37). Paraguay, Uruguay and Argentina from
Rio Negro north into the Andean foothills of southern Bolivia. Alti-
tudinal range from sea level to not over 2500 meters above. An
established colony of imports 42 km. southeast of Maturin, Monagas,
northeastern Venezuela, may have been transported from Bolivia,
according to Butterworth (1960, p. 517). The precedence of the
colonies in Curasao and Aruba, Netherlands West Indies, has not
been determined.
Characters. Those of the species.
Variation. Generally as given for the species. Lauchax from
Uruguay and eastern Argentina are slightly darker throughout than
those of the Argentine Andes. A series of 10 specimens from Gua-
challa and one specimen from Orloff, both localities in eastern Chaco,
Paraguay, are nearest the Andean lauchas but average smaller and
paler throughout with white under parts, lower third of sides of body,
muzzle, arms and upper surface of hind feet. The Guachalla speci-
mens, taken September 3-5, 1945, are in prime pelage; the Orloff in-
dividual, dated November 15, 1945, is in old worn pleage. There
154 FIELDIANA: ZOOLOGY, VOLUME 46
is complete agreement in external characters between the Guachalla
specimens and the colored figure of the type of Mus bimaculatus
Waterhouse (1839, pi. 12), taken in June.
Of 13 specimens from 42 kilometers southeast of Maturin, Mo-
nagas, Venezuela, which were collected and recorded by Butter-
worth (1960, p. 517), 4 are described as juvenals; the remaining
9, represented by skins and 6 skulls, are at hand. They include one
juvenal and two subadults. Pelage of all is comparatively short and
thin as in old summer pelage of their southern hemisphere relatives.
Upper parts agree in color with the series from Guachalla, Chaco,
Paraguay; under parts vary from white to grayish. The tail aver-
ages shorter, actually and relative to head and body length, than
in any other series examined but in this respect they are also most
like the Paraguayan lauchas.
Taxonomy. First accurate characterization of mice of the re-
stricted genus Calomys was presented by Felix Azara in the French
edition (1801, p. 102) of his account of the mammals of Paraguay.
The vernacular name "laucha" was applied to the three speci-
mens described. In the later Spanish edition (1802, p. 96) only
one laucha was described. There also appears in the Spanish edi-
tion a small mouse called "bianco debaxo" or white-bellied mouse.
Tate (1932b, footnote, p. 11) thought the bianco debaxo was a laucha
for which the technical name Mus dubius Fischer was available.
Cabrera (1961, pp. 477-478) agreed and treated the white-bellied
bimaculatus Waterhouse and the gray-bellied bonariensis Osgood, as
subspecies of Calomys dubius.
Measurements given by Azara for the three lauchas of the French
edition and those for the laucha and the bianco debaxo of the Spanish
edition are as follows, in millimeters converted from Spanish inches.
Hind foot Ear
Total with from
Edition
length
Tail
claw
crown
laucha
cf French
110
46
15
7
laucha
9 French
100
-
laucha
9 French
81
laucha
- Spanish
127
54
16
9
bianco debaxo
- Spanish
135
42
18
13.5
External measurements of the bianco debaxo are not those of any
known Calomys. The animal might be a Thalpomys but this possi-
bility need not be discussed here.
Specimens from the type locality in the vicinity of Asuncion are
not available. Topotypes of H. laucha laucha may be nearer the
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 155
small white-bellied specimens from Guachalla, Chaco, or they may
be like the larger, darker Uruguayan and eastern Argentine lauchas.
Whatever the affinities, too little is known of seasonal and geographic
variation to prove subspecific distinction between any two popula-
tions of the species.
The figured skull accompanying the original description of the
Uruguayan Mus bimaculatus Waterhouse (cited in the above syn-
onymy) is inaccurate in several respects. It is shown with the in-
terorbital constriction exaggerated and the nasals tapered behind
to a point, instead of being square or broadly rounded. The mouse
described and figured by Waterhouse (supra cit.) as Mus gracilipes
is smaller than the type of bimaculatus but the difference in size lies
well within the limits of individual variation. Measurements given
by Gyldenstolpe (1932, p. 143) for "Hesperomys gracilipes" do not
correspond to the type, as implied, or to any other member of the
genus Calomys.
The body size of the type of Hesperomys laucha musculinus
Thomas, from Maimara, Jujuy, equals that of small adults of the
larger species C. callosus Rengger. However, the molar row length
in musculinus, given as 3.6 mm., is diagnostic of Calomys laucha.
Presumably because of the disparity in gross size between the types
of musculinus and laucha, Thomas subsequently raised musculinus
to specific rank and described cortensis as a subspecies of it. In this
connection Thomas observed that the type series of cortensis in-
cluded "a single old male skull one of those overgrown examples
which often render distinction of size so difficult -[that] measures
no less than 26 mm. in greatest length; but this is obviously abnor-
mal, the type being of about the usual adult size [24.5 mm.]." This
statement adds weight to my opinion that the type of musculinus,
also with skull length 26 mm., is an "overgrown" individual of
C. laucha. Specimens at hand from the type region of musculinus
and its erstwhile subspecies cortensis cannot be separated from other
Argentine and Uruguayan lauchas.
Hesperomys murillus, described by Thomas in 1916, was recorded
by the same authority in 1897 as Oryzomys laucha and again under
this same name in 1898. Subsequent specific separation was based
on the insignificant character of tail length, "which nearly or quite
equals the head and body in length." Hesperomys bimaculatus bo-
nariensis Osgood, like murillus, is nothing more than another name
for the same small pampas Calomys already described from the same
region as laucha, bimaculatus and gracilipes. No representative of
156 FIELDIANA: ZOOLOGY, VOLUME 46
Hesperomys murillus cordovensis is at hand, but there is nothing in
the original description or in the distributional pattern of related
forms that suggests racial distinction of the Cordoba laucha. A
specimen from Chumbicha, Catamarca, collected by Emilio Budin
and identified by Thomas as cordovensis, is not separable from other
Argentine lauchas.
The confusion attending the systematics of Calomys is com-
pounded by use of such similar sounding trivial names as murillus,
muriculus, musculinus, and cortensis, cordovensis.
Baiomys hummelincki Husson from the island of Curacao, Nether-
lands West Indies, most nearly resembles new summer pelage repre-
sentatives of typical Calomys laucha laucha but is more brightly
colored ochraceous-buff and smaller throughout. The original de-
scription is based on a skin and skull (type) and a skull only from
Curacao, and four specimens from Aruba represented by two skins
with skulls and two specimens in alcohol. External measurements
given are minimal for Calomys laucha but were taken from the
shrunken, preserved specimens. Cranial measurements are also
small. The figure of the type skull and its greatest length, 18.6,
are those of a Juvenal. The largest skull, evidently of an adult,
measures 19.3. The figures of the head and feet of one of the speci-
mens in alcohol from Aruba are of a Juvenal. Copies of these excel-
lent drawings are used here (fig. 38) for illustrating the external
characters of Calomys laucha. Husson's description of the Curacao
and Aruba specimens of Calomys laucha (= Baiomys hummelincki)
and two skins and three skulls at hand of the same material agree
best with the Venezuelan import colony. It has been suggested that
the latter may have been transported from Bolivia but it is equally
possible that it proceeded from Curacao or Aruba. This still does
not determine the native habitat or habitats of the original imports.
In any event, the differences between the West Indian and Venezu-
elan populations are of the same order as differences between pocket
populations in the southern hemisphere. Suppression of the winter
pelage in the northern hemisphere lauchas is a niche variable. More
collections are needed at regular intervals for measuring the rate of
evolution of Calomys laucha in Venezuela and the Netherlands West
Indies.
Measurements. See Table 3 (p. 190).
Specimens examined. 67. PARAGUAY. Chaco: Guachalla,
10 (CNHM); Orloff, 1 (CNHM). URUGUAY. Minos: Paso de
Averias, 2 (CNHM) ; Polanco, 1 (CNHM). ARGENTINA. Jujuy:
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 157
Maimara, 2 (MACN). Tucuman: Conception, 3 (CNHM). Cata-
marca: Chumbicha, 1 (CNHM). Buenos Aires: Torrecita, 13 in-
cluding the type of bonariensis Osgood (CNHM); near Henderson,
4 (CNHM); Dorrego, 10 km. northwest, 7 (CNHM); Algarrobo,
2 (MACN). Rio Negro: Chimpay, 7 (CNHM); Choele-Choel,
2 (MACN). VENEZUELA. Monagas: Maturin, 9 (LACM).
CURACAO. Plan tage Jongbloed, 1 (RNHL). ARUBA. Shiri-
bana, 1 (RNHL); Airport Dakota, Boca Morto, 1 (RNHL).
Calomys laucha tener Winge
Hesperomys tener Winge, 1888, E Mus. Lundii, 1, no. 3: 15, pi. '2, fig. 3 (skull).
Gyldenstolpe, 1932, Kungl. Sv. Vet. Akad. Handl., (3), 11: 75 selection
of lectotype.
[Hesperomys] tener, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141 classi-
fication.
Eligmodontia tener, Shufeldt, 1926, Rev. Mus. Paulista, 14: 503, 508, 563, 568,
pi. 2, fig. 6 (skin) BRAZIL: Sao Paulo (Piracicaba).
Type. Female, Zoological Museum, Copenhagen, no. 252.
Type locality. Rio das Velhas, Lagoa Santa, Minas Geraes,
eastern Brazil.
Distribution (fig. 37). Eastern Brazil; known from the states of
Minas Geraes and Sao Paulo but probably occurs, also, in Goias and
the southeastern coastal states of Brazil.
Characters. The original description of tener is based on a com-
parison with the sympatric congener Hesperomys callosus expulsus.
It remains to be shown that tener differs subspecifically from typical
laucha.
Remarks. Vieira (1953, p. 148) has recorded "Hesperomys tener"
from Sao Paulo. Measurements given for two specimens are not
those of any known species of Calomys.
Cabrera's (1961, p. 481) inclusion of "Ksperomys [sic] lepidus
lepidus Sanborn, Public. Mus. Javier Prado, Zool. num. 5, 1950: 3,"
in the synonymy of Calomys tener Winge is an obvious typograph-
ical error. Cabrera (op. cit., p. 480) cites the same reference cor-
rectly under Calomys lepidus lepidus Thomas.
Measurements. Those of the lectotype and two cotypes are from
the original description. External measurements taken from the dry
skin: head and body, 95 ("stretched"), 82, 74; tail, 67 ("stretched"),
57, 61; hind foot, 16.5, 15, 16; ear, 13, 13.5, 12.5; greatest length of
skull (of lectotype only), 19.7; zygomatic breadth, 12; upper molar
row, 3.3.
Specimens examined. None.
158 FIELDIANA: ZOOLOGY, VOLUME 46
EXPLANATION OF FIGURE 39
Calomys lepidus: collecting localities and collectors.
Type localities in boldface.
Calomys lepidus lepidus (1-7)
PERU
1. Carhuamayo, Junfn. C. C. Sanborn at 14,500 feet.
2. Junin, Junin. C. Jelski.
3. Tambo Polanco, San Miguel, Ayacucho. C. Kalinowski.
4. San Jenaro, Santa Inez, Huancavelica. C. Kalinowski.
5. Lauramarca, Cusco (3996 meters) . O. Garlepp.
6. Lucre, Cusco. O. Garlepp at 3500 meters.
6. Sucre, Cusco = Lucre (?..).
7. La Raya Pass, Cusco. E. Heller at 14,010 feet.
Calomys lepidus ducillus (8-19)
PERU
8. San Ant6n, Puno. P. O. Simons at 3800 meters.
9. Picotani, Puno. C. C. Sanborn at 14,000 feet.
10. Posoconi, Puno. C. C. Sanborn at 13,500 feet.
11. Santa Lucia, Puno. M. R. Portugal.
12. Chucuito, Puno. C. C. Sanborn.
13. Collacachi, Puno. C. C. Sanborn.
14. Yunguyo, 6 miles south, Puno. C. C. Sanborn at 13,000 feet.
15. Pairumani, Puno. O. P. Pearson at 13,000 feet.
16. Huacullani, Puno. C. C. Sanborn.
17. Sumbay, Arequipa. C. C. Sanborn.
18. Salinas, Arequipa. C. C. Sanborn and J. M. Schmidt at 13,500 feet.
CHILE
19. Ojos de San Pedro, Antofagasta. C. Koford.
Calomys lepidus carillus (20-21)
BOLIVIA
20. La Cumbre, La Paz. G. H. H. Tate at 15,200 feet.
21. Choro, Cochabamba. P. O. Simons at 3500 meters; F. Steinbach at
3500 meters.
Calomys lepidus argurus (22)
ARGENTINA
22. Abrapampa, Jujuy. E. Budin.
Calomys lepidus lepidus
" " _/ //
ducillus
O " " //
w canllus
FIG. 39. Collecting localities of the subspecies of Calomyx Icpidns. See
opposite page for explanation.
159
160 FIELDIANA: ZOOLOGY, VOLUME 46
Calomys lepidus Thomas. (Synonymy under subspecies.)
Distribution (figs. 28, 39). Temperate zone grasslands and scrub-
lands of the southern half of Peru, western Bolivia, extreme north-
western Argentina and northeastern Chile; altitudinal range between
3000 and 5000 meters above sea level.
Characters. Smallest of phyllotines in average size; pelage long,
thick, smooth or crinkly; tail between one- third and two- thirds of
length of head and body combined, whitish, buffy or gray above,
slightly paler beneath, terminal portion sometimes darker than basal
portion; fifth hind toe, less claw, not extending to tip of first phalanx
of fourth toe; heel and proximal portion of sole hairy, the tarsal
tubercle partially hidden; whitish postauricular patches present;
upper parts of body buffy to tawny more or less suffused with gray
anteriorly, lined or peppered with black posteriorly, the black tips
of guard hairs prominent only in juvenals; under parts sharply de-
fined gray or white with plumbeous basal portions of hairs showing
through; lateral lines, when present, not well defined, often meeting
posteriorly at base of tail; mammae 8 to 10 but usually not more
than 6 detectable; supraorbital region of skull (figs. 29, 30, 40) par-
allel-sided or slightly concave mid-frontally, the edges square, never
beaded; mid-frontal width less than greatest width of rostrum; pos-
terior tip of lower incisor forming a ridge without capsular projection;
dental characters (fig. 33) as for the genus.
Comparisons. The small size and vole-like appearance are alone
sufficient to distinguish Calomys lepidus from its three Mus-\ike con-
geners. Cranially, C. lepidus is nearest sorellus. The externally sim-
ilar though much larger vole-like Phyllotis sublimis and Galenomys
garleppi inhabit the same parts of the altiplano of southern Peru
and western Bolivia. Juvenals of Phyllotis sublimis have been con-
fused with adult Calomys lepidus, but differences between the two
are obvious when size and shape of ears and hind feet, cranial char-
acters, and size and structure of incisors and molars are taken into
account.
Variation. A bright buff, or tawny, color phase characterizes
some series, and a dusky gray phase characterizes others. In the
bright phase, head and shoulders are contrastingly grizzled in speci-
mens from the more arid localities. In the dusky phase, upper parts
and sides of body are fairly uniform in color except for the darker
mid-dorsal line or band. Color of tail varies independently, but there
are more dark tails among individuals of the dusky phase than in
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 161
FIG. 40. Calomys lepidus. Dorsal aspect of skulls showing variation in size (-X 2).
specimens of the bright phase. The color phases may represent two
stages of seasonal pelage succession or each may be a constant in a
given locality. The data are tabulated as follows:
No. of Date of
Calomys lepidus lepidus (Peru) specimens capture Phase
Carhuamayo, Junfn 2 Feb. 21-23 bright
Tambo Polanco, Ayacucho 1 Nov. 27 dusky
San Jenaro, Huancavelica 1 Dec. 24 dusky
Calomys lepidus ducillus (Peru)
Yunguyp, Puno 3
Posoconi, Puno 5
Santa Lucfa, Puno 1
Sumbay, Arequipa 1
Huacullani, Puno 3
Chucuito, Puno 1
Collacachi, Puno 8
Picptani, Puno 1
Salinas, Arequipa 5
Calomys lepidus carillus (Bolivia)
Choro, Cochabamba 1 June 27 dusky
La Cumbre, La Paz 7 Feb. 12-15 dusky
Variation in tone of bright and dusky phases parallels the con-
dition in Phyllotis darwini from the same localities. The bright
Carhuamayo and dusky Ayacucho and Huancavelica specimens of
Calomys I. lepidus are much more saturate than corresponding rep-
resentatives of C. I. ducillus. The Bolivian carillus is represented
by individuals of one color phase which are slightly darker than
dusky specimens of ducillus and practically indistinguishable from
dusky lepidus.
May 1-2
May 7-9
July 23
Aug. 18
Aug. 25-26
Sept. 8
Sept. 11-14
Sept. 15
Oct. 6-7
dusky
dusky
bright
bright
bright
bright
bright
bright
bright
162 FIELD IANA: ZOOLOGY, VOLUME 46
Most juvenals resemble small adults and growth continues through-
out life.
Habits and habitat. The following observations on Calomys lepi-
dus ducillus are quoted from Pearson (1951, p. 141) : "Only seven of
these little mice were caught, most of them at night in grassy places
or in stone walls such as those surrounding corrals in open country.
Hesperomys was apparently more abundant than this catch indicates,
for the owls at Pairumani (Puno, Lake Titicaca region) caught more
Hesperomys than they did any other species. The nocturnal habits
and grassland preferences of these mice make them natural owl prey,
and it is possible that they are not attracted to trap baits (nuts were
used for bait in most cases). Phyllotis sublimis was frequently
trapped nearby.
"A female on August 29 had an open vagina and thick uterine
horns, but no female earlier than this contained embryos and none
was caught later. Two males in July had testes 5.5 and 7 mm. long.
"The only ticks encountered on any animal in the region were
found on the ear of a Hesperomys from Pairumani."
The only other note on the habits of Calomys lepidus is a mis-
leading one made by Thomas. In connection with the description
of C. lepidus argurus, Thomas (1919d, p. 130) observed that it was
the "dry-area representative of the forest H. carillus." The type
and only specimen of Calomys lepidus carillus known to Thomas is
from the grasslands of Choro, Cochabamba, in the Bolivian Andes.
Calomys lepidus lepidus Thomas
Hesperomys (Calomys) bimaculatus var. lepidus Thomas, 1884, Proc. Zool.
Soc. London, 1884: 454, pi. 42, fig. 2 (color), pi. 44, figs. 10, 11 (skull),
fig. 12 (ear), fig. 13 (hind foot).
[Hesperomys} lepidus, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
E[ligmodontia] lepida, Thomas, 1900, Ann. Mag. Nat. Hist., (7), 6: 298
comparison in text.
Hesperomys lepidus lepidus, Sanborn, 1950, Mus. Hist. Nat. "Javier Prado,"
(A), Zool., no. 5, p. 3 PERU: Junin (Carhuamayo).
Hesperomys carillus marcarum Thomas, 1917, Smithsonian Misc. Coll., 68,
no. 4, p. 1 PERU: Cusco (type locality, Lauramarca). Thomas, 1920,
Proc. U. S. Nat. Mus., 58: 231 PERU: Cusco (La Raya Pass; Sucre
[= Lucre].
Calomys lepidus marcarum, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 480 classification.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 163
Type. Male, British Museum (Natural History) no. 85.4 1.43;
collected by Constantin Jelski.
Type locality. Junin, Junin, Peru.
Distribution (fig. 39). Andes of central Peru in the Lago Junin
and Rios Apurimac-Urubamba drainage systems, departments of
Junin, Huancavelica, Ayacucho, Apurimac and Cusco; altitudinal
range, from approximately 3500 to 4500 meters above sea level.
Characters. Upper parts tawny with or without a dark lining
on posterior half.
Variation. As described for the species (p. 160).
Remarks. Specimens from Carhuamayo, Junin, are practically
topotypes. One specimen from Huancavelica and another from Aya-
cucho agree with the published descriptions of Calomys carillus mar-
carum Thomas from Cusco. In view of the small difference of a
clinal nature between lepidus of central Peru and ducillus of southern
Peru the occurrence of a geographically intermediate race is extremely
doubtful.
Measurements. See Table 4 (p. 191).
Specimens examined. 4, all in collection of Chicago Natural
History Museum. PERU. Junin: Carhuamayo, 2. Huancavelica:
San Jenaro, Santa Ine"z, 1. Ayacucho: Tambo Polanco, San Miguel, 1.
Calomys lepidus ducillus Thomas
Eligmodontia ducilla Thomas, 1901, Ann. Mag. Nat. Hist., (7), 7: 182.
(Hesperomys) ducilla, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
Hesperomys ducillus, Pearson, 1951, Bull. Mus. Comp. Zool., 106: 141
PERU: Puno (Pairumani).
Hesperomys lepidus ducillus, Sanborn, 1950, Mus. Hist. Nat. "Javier Prado,"
(A), Zool., no. 5, p. 4 -PERU: Puno (Posoconi; Hacienda Picotani;
Chucuito; Hacienda Collacachi; Santa Lucfa; Yunguyo); Arequipa (Sa-
linas; Sumbay).
Hesperomys lepidus ducillus, Koford, 1954, Invest. Zool. Chilenas, 2: 6, p. 95
CHILE: Anlofagasta (Ojos de San Pedro).
Calomys lepidus ducillus, Cabrera, 1961, Rev. Mus. argent ino Cienc. Nat.
"Bernardino Rivadavia," 4: 480 classification.
Type. Female, British Museum (Natural History) no. 1.1.1.1;
collected June 28, 1900, by Perry O. Simons.
Type locality. San Anton, Lake Titicaca region, Puno, Peru;
altitude, 3800 meters above sea level.
164 FIELDIANA: ZOOLOGY, VOLUME 46
Distribution (fig. 39). Altiplano of southern Peru, northeastern
Chile, western Bolivia and probably northern Argentina; altitudinal
range, 3500 to 4500 meters above sea level.
Characters. Paler than typical lepidus.
Variation. As described for the species (p. 160). The series
from Salinas, another from Collacachi, and the only specimen from
Huacullani exhibit a strongly contrasting grizzling on head and
shoulders.
Remarks. Specimens from Picotani and Posoconi are practically
topotypical. The individual from the first locality is in the bright
color phase, the series of five from the second locality is in the dusky
pelage phase.
Measurements. See Table 4 (p. 191).
Specimens examined. 28, all in collection of Chicago Natural
History Museum. PERU. Arequipa: Salinas, 5; Sumbay, 1. Puno:
Huacullani, 3; Yunguyo, 6 miles south, 3; Santa Lucia, 1; Picotani,
1; Chucuito, 1; Posoconi, 3 miles west of Asillo, 5; Hacienda Colla-
cachi, 8.
Calomys lepidus argurus Thomas
Hesperomys carillus argurus Thomas, 1919. Ann. Mag. Nat. Hist., (9), 4: 130.
Type. Female, British Museum (Natural History) no. 19.8.1.21;
collected February 17, 1919, by Emilio Budin.
Type locality. Abrapampa, Jujuy, Argentina; altitude, 3500
meters above sea level.
Distribution (fig. 39). Known from type locality only.
Characters. According to the original description, "essential
characters apparently quite as in the true H. carillus, but colour
throughout much paler."
Remarks. The pale argurus may prove to be the northern Argen-
tine representative of Calomys lepidus ducillus. Thomas ignored
both lepidus and ducillus in his description of argurus.
Measurements. See Table 4.
Specimens examined. None.
Calomys lepidus carillus Thomas
Eligmodontia carilla Thomas, 1902, Ann. Mag. Nat. Hist., (7), 9: 133.
[Hesperomys] carilla, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification. Thomas, 1920, Proc. U. S. Nat. Mus., 58: 231 comparison.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 165
Hesperomys lepidus montanus Sanborn, (part), 1950, Mus. Hist. Nat. "Javier
Prado," (A), Zool., no. 5, p. 4 BOLIVIA: La Paz (type locality, La Cum-
bre, 15,200 feet altitude); the type and one subadult only.
Type. Male, British Museum (Natural History) no. 2.1.1.55;
collected July 1, 1900, by Perry 0. Simons.
Type locality. Choro, Cochabamba, Bolivia; altitude 3500 me-
ters above sea level.
Distribution (fig. 39). Upper Rio Mad re de Dios drainage sys-
tem in La Paz and Cochabamba Departments, Bolivia; altitudinal
range, 3500 to 4800 meters above sea level.
Characters. Slightly darker than dusky color phase representa-
tives of ducillus.
Variation. As for the species (p. 160).
Remarks. The difference between dusky phase near topotypes
of Calomys lepidus ducillus and Bolivian carillus is slight. However,
the suspicion that the dark Bolivian specimens represent the bright
color phase of carillus makes at least provisional recognition of the
name advisable.
Hesperomys lepidus montanus Sanborn is based on a series of 4
subadults including the type, and 4 juvenals referable to Phyllotis
sublimis. Two of the subadult Calomys are indistinguishable from
a topotype of carillus, a specimen not available at the time of the
description of montanus. The third subadult and, presumably, the
type, are darker.
Measurements. See Table 4 (p. 191).
Specimens examined. 4. BOLIVIA. Cochabamba: Choro, 1
(CNHM). La Paz: La Cumbre, 3 (AMNH).
Calomys callosus Rengger. (Synonymy under subspecies.)
Distribution (figs. 28, 41). Forest fringes and scrublands of
southern Brazil, Paraguay, Bolivian Chaco; plains of northern Ar-
gentina, and eastern slopes of Andes from La Paz, Bolivia, into the
Sierras Pampeanas in Argentina as far as Cordoba; altitudinal range
from near sea level to approximately 200 meters above.
Characters. Largest species of the genus; pelage long and mod-
erately lax, or short and adpressed; tail from approximately 60 per
cent to 90 per cent of combined head and body length, faintly to
sharply bicolor; fifth hind toe, less claw, extending from base to
middle of first phalanx of fourth toe; pale postauricular patches pres-
O
00
OU
1 -
o=
5 o'
I f
m
!!
1
E
c>
7
CQ
.. c
-H O
TT
c
S i g
D X
5, H
O ra *H
O
z
o
h
w
> A 5? ^^ --T "
* U < S ~
"^ S
~
-j jg
N3
dcdt-^oc oi <3o'~
B
E
>
c,
-
c -
T
&
1
c ^
5
O
_o
c
o
.c
K
o
L~
t> 10
'3_
m *
1
E s j .2 1 1 1
1 * 2" W . - 2
-
ug25
S g
2 .2
x
CQ
166
O
o
167
168
FIELDIANA: ZOOLOGY, VOLUME 46
ent or absent; upper parts of body ochraceous to tawny with a fine
or coarse mixture of black or dark brown; weakly defined ochraceous
lateral band sometimes present; under parts gray with or without a
FIG. 42. Calomys callosus callosus. Dorsal aspect of skulls showing variation
in size (-X2).
thin buffy wash; mammae 8 to 14; borders of supraorbital region of
skull (figs. 29, 30, 42, 54,6) divergent from anterior angle backward,
strongly beaded and forming broad ledges in fully mature individ-
uals; mid-frontal width always more than greatest width of rostrum;
interparietal well developed; dental characters (figs. 43, 44, 56,6) as
for the genus.
Comparisons. Calomys callosus is readily distinguished from all
other members of the genus by larger size and specialized form of
the supraorbital region. Large individuals of C. callosus resemble
small ones of Zygodontomys (for comparison see p. 199 and figs. 34
and 44). C. callosus and C. laucha are sympatric throughout the
greater part of their respective ranges. Both are Afws-like in ap-
pearance and, to a certain extent, in habits. Diagnostic characters
given in the keys and descriptions are adequate for separating them.
Variation. Individual and geographic variations in size lie with-
in the same narrow limits. Color of adults in a given season is uni-
form throughout the range of the species. However, one specimen
from Goias, Brazil, has dark under parts. Young individuals aver-
age darker than fully mature ones. Winter pelage is soft, long, and
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 169
thick; summer pelage is short, thin and, in warmer localities, slightly
hispid. Pattern of seasonal variation is local and, in Andean local-
FIG. 43. Calomys callosus. a, palate; 6, lower molars of juvenal; c, d, worn
upper and lower molars respectively, of adult.
ities, may depend on altitude. Most marked condition of winter
molt is found in specimens taken in June from Calilegua, Jujuy,
and from localities in Tucuman. In a large series from Concepcion,
Tucuman, 3 specimens taken in May are in good pelage, 9 speci-
mens taken in June are molting and 4 are in good pelage. In the
same series, 2 specimens taken in December are in well-marked
summer molt. Four specimens taken in February from Paraguay
FIG. 44. Upper and lower right molars of a, Calomys callosus; b, Zygodontomys
breeicauda; c, Phyllotis griseoflaviis.
170
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 171
have a short new summer pelage that averages darker than the
longer winter pelage of other Paraguayan members of the species.
Habits and habitat. Calomys callosiLs is the common mouse of
gallery and scrub forests. It has invaded cultivated fields and
houses, where it lives side by side with Mus musculus. In his de-
scription of C. callosus, Rengger stated that the mice dig tunnels
several feet long by about two inches wide and nest there in pairs.
Rengger also observed the species foraging in daylight for seeds
and roots.
Rodents recorded by Kuhlhorn (1952, p. 116; 1954, p. 72) as
Hesperomys musculinus or H. laucha musculinus are certainly refer-
able to the large species Calomys callosus. Their weight, given as
20-30 grams for subadults and 35-38 grams for fully developed in-
dividuals, corresponds to the weight of mice the size of C. callosus
and averages more than twice the weight of mice the size of C. laucha.
Kiihlhorn's specimens were taken in gallery forest where H. laucha is
unknown, and no specimens were found, after intensive trapping for
several weeks, in open country, or in campos, where H. laucha might
occur. Kuhlhorn noted that the mice were most active at night but
could still be observed in their runways between 6 and 7 o'clock in
the morning. Although traps were always set, only one Calomys
was taken at noon. The runways measured from 3 to 5 centimeters
in width. Evidently, a mouse used only its own runway system.
Once it was trapped out, no other mouse moved in. According to
Kuhlhorn, the species nests in holes in underbrush or rotting tree
stumps. The above observations were made during the dry season
in April and May, 1938. No nestlings, embryos or lactating females
were taken at that time. Stomach contents revealed mainly vege-
table matter with a small quantity of insects. Unfortunately, mice
collected by Kuhlhorn on Krieg's South American expedition were
lost during the war.
Calomys callosus callosus Rengger
Mus callosus Rengger, 1830, Natiirg. Saug. von Paraguay, Basle, p. 231.
Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 182 species unidentifiable.
Oryzomys callosus, Thomas, 1898, Boll. Mus. Zool. Anat. Comp., Torino, 13,
no. 315, p. 3 PARAGUAY: Conception (Rfo Apa, Concepci6n); Chaco
(Rio Pilcomayo); ARGENTINA: Jujuy (San Lorenzo) ; Corn entes (Goya).
Eligmodontia callosa, Thomas, 1902, Ann. Mag. Nat. Hist., (7), 9: 241
ARGENTINA: Cordoba (Cruz del Eje).
Hesperomys callosus, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141-
classification.
172 FIELDIANA: ZOOLOGY, VOLUME 46
H[esperomys] callosus callosus, Yepes, 1935, Rev. Inst. Bacteriol., Buenos Aires,
7: 227 ARGENTINA: all northern and central provinces.
Oryzomys (?) venustus Thomas, 1894, Ann. Mag. Nat. Hist., (6), 14: 359
ARGENTINA: Cordoba (type locality, Cosqufn).
[Hesperomys] venustus, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
Hesperomys venustus, Thomas, 1919, Ann. Mag. Nat. Hist., (9), 4: 154
ARGENTINA: Salta (Tartagal). Thomas, 1920, op. cit., (9), 5: 190
ARGENTINA: Jujuy (Villa Carolina). Thomas, 1925, op. cit., (9), 15:
578 BOLIVIA: Tarija (Yacuiba; Carapari). Thomas, 1926, op. cit., (9),
17: 604 ARGENTINA: Tucumdn (Cerro del Campo, Burruyacu).
Calomys venustus venustus, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 481 fecundus Thomas, a synonym.
Eligmodontia callosa boliviae Thomas, 1901, Ann. Mag. Nat Hist., (7), 8: 253
BOLIVIA: La Paz (type locality, Rfo Solocame, 1200 meters above
sea level; Yungas; Astilleros).
[Hesperomys callosus} boliviae, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17:
141 classification.
Hesperomys callosus boliviae, Osgood, 1916, Field Mus. Nat. Hist., Zool. Ser.,
10: 207 BOLIVIA: Beni (Trinidad). Sanborn, 1950, Mus. Hist. Nat.
"Javier Prado," (A), Zool., no. 5, p. 3 BOLIVIA: La Paz (Pitiguaya).
Hesperomys venustus callidus Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17:
182 ARGENTINA: Corrientes (type locality, Goya, altitude, 600 feet).
Hesperomys muriculus Thomas, 1921, Ann. Mag. Nat. Hist., (9), 8: 623
BOLIVIA: Santa Cruz (type locality, San Antonio, Parapeti, about
250 km. south of Santa Cruz de la Sierra).
Hesperomys fecundus Thomas, 1926, Ann. Mag. Nat. Hist., (9), 17: 321
BOLIVIA: Tarija (type locality, Tablada, altitude, 2000 meters).
Hesperomys musculinus, Kiihlhorn (not Thomas), 1952, Zeitschr. Saugetierk.,
18: 116 habits.
Hesperomys laucha musculinus, Kiihlhorn (not Thomas), 1954, Saugetierk.
Mitt., 2: 72 BRAZIL: Mato Grosso (Alto Parana; Rio Ivinheima).
[?] Necromys conifer Ameghino, 1889, Act. Acad. Nac. Cienc. Cordoba, 6: 120,
pi. 4, figs. 17, 18 (dentition) ARGENTINA: Buenos Aires (type locality,
Buenos Aires [Pleistocene]).
Type. Not known to be in existence. The bulk of Rengger's
Paraguayan collection was lost before it could be sent to Europe.
It is possible, however, that a few specimens reached the natural
history museum of Aarau, Switzerland.
Type locality. "Taken on the banks of the Rio Paraguay at
about 27 degrees latitude," i.e., opposite mouth of Rio Bermejo,
Department of Villa del Pilar, Paraguay.
Distribution (fig. 41). Mato Grosso, Brazil, Paraguay, Bolivian
Chaco, plains of northern Argentina and eastern slopes of Andes
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 173
from La Paz, Bolivia, into the Sierras Pampeanas of Argentina as
far south as Cordoba; altitudinal range to 2000 meters.
Characters. Those of the species except that the under parts are
not dark gray.
Taxonomy. The original description of Mus callosus Rengger,
published in 1830, is unmistakably that of the larger of the two
known species of Paraguayan Calomys. There is absolutely no basis
for the conjecture advanced by Thomas (1916b, p. 182) that callosus
is the same as Mus musculus. Rengger compared callosus with, not
to, as implied by Thomas, the Old World house mouse because the
two animals are superficially similar and frequently occupy the same
habitat. On pages 228-229 of his work Rengger makes clear the dis-
tinction between the "vier einheimische [cricetine] and zwei aus-
landische [murine] Nager" he found in Paraguay. Regarding meas-
urements, those of callosus are practically the same as those of a
number of specimens recorded or described by Thomas as members
of the large species of Hesperomys (= Calomys). The name callidus
proposed by Thomas for mice identified by authors as callosus
Rengger is a gratuitous synonym.
The characterization of Eligmodontia callosa boliviae Thomas does
not indicate substantial difference from Paraguayan callostis. Meas-
urements of the types of the two forms are not significantly different,
and specimens at hand from various localities in the Amazonian
drainage of Bolivia are not separable from the Paraguayan form.
The name fecundus is based on southern Bolivian individuals with
nothing more distinctive than possession of 14 mammae instead of
the more frequent 10. In addition to the type, Thomas recorded
under the name Hesperomys venustus many specimens from various
localities in northern Argentina and southern Bolivia. Abundant
material at hand from the same regions shows nothing by which
venustus can be separated from so-called fecundus or either of them
from representatives of true callosus. Another named form of south-
ern Bolivian callosus is muriculus Thomas. This is said to be "readily
recognizable by its comparatively dark colour." Measurements and
coloration of the type indicate a young individual. An adult from
Tacuara, Chuquisaca, just northwest of San Antonio de Parapeti,
type locality of muriculus, is indistinguishable from comparable
specimens of callosus.
Measurements. See Table 5 (p. 192).
Specimens examined. 113. BRAZIL. Mato Grosso: Descal-
vados, 7 (CNHM); Urucum de Corumba, 9 (CNHM). BOLIVIA.
174 FIELDIANA: ZOOLOGY, VOLUME 46
Beni: Trinidad, 1 (CNHM). Santa Cruz: Buena Vista, 4 (MACN,
1; CNHM, 3); San Carlos, Ichilo, 2 (MACN, 1; CNHM, 1); Tacu-
ara, 1 (CNHM). Tarija: Villa Montes, 2 (CNHM). PARAGUAY.
Chaco: Guachalla, Rio Pilcomayo, 6 (CNHM); Rio Pilcomayo, 15
miles above mouth at Rio Paraguay, 5 (CNHM). ARGENTINA.
Salta: Aguaray, 3 (MACN) ; Rio Santa Maria, 2 (MACN). Jujuy:
Calilegua, 11 (CNHM). Tucuman: Burruyacu, 3 (CNHM); Tafi
Viejo, 2 (MACN); Conception, 55 (MACN, 3; CNHM, 52).
Calomys callosus expulsus Lund
Mus expulsus Lund, 1839, Ann. Sci. Nat., Paris, 11: 233 BRAZIL: Minas
Gerais (Rio das Velhas) ; name only. Lund, 1841, Afh. K. Danske Vidensk.
Selsk. Nat. Math., 8: 134, 266, 280, 294 description and records. Schinz,
1845, Syn. Mamm., 2: 194 diagnosis.
Hesperomys expulsus, Burmeister, 1854, Syst. Ueber. Thiere Brasil, 1: 175
BRAZIL: Minas Gerais (Lagoa Santa). Giebel, 1855, Odontographie,
p. 50, pi. 21, fig. 76 (dentition). Giebel, 1857, Abh. naturw. Ver. Sachsen
u. Thiiringen, Halle, 1: 191 seq., p. 5, fig. 8 (skull) osteology. Winge,
1888, E Mus. Lundii, 1, no. 3: 16 (description), pi. 1, fig. 1 (head), fig. 2
(hind foot), pi. 2, fig. 4 (skull), 4a (molar) BRAZIL: Minas Gerais (Lagoa
Santa). Gyldenstolpe, 1932, K. Sv. Vet. Akad. Hand!., (3), 11: 75.
[Hesperomys] expulsus, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
[Oryzomys] expulsus, Trouessart, 1898, Cat. Mamm., p. 528 classification.
[Zygodontomys] expulsus, Trouessart, 1905, Cat. Mamm., Suppl., p. 423.
Type. In Zoological Museum, Copenhagen.
Type locality. Lagoa Santa, Minas Gerais, Brazil.
Distribution (fig. 41). Eastern Brazil; known only from Minas
Gerais and Goias but the range probably extends from the Rios
Sao Francisco and Parana to the coast.
Characters. Possibly darker throughout than typical callosus.
Remarks. Cotypes of Mus expulsus Lund have been redescribed
and figured by Giebel (supra cit.) and Winge (supra cit.). The ex-
tremely detailed and accurate evidence leaves no doubt of the spe-
cific identity of expulsus with callosus. Subspecific status of expulsus
may be postulated, however, on biogeographic grounds. A specimen
from Sao Domingo, Goias, the only one examined that can be re-
ferred to expulsus, differs from typical callosus by its extremely dark
under parts.
Measurements. See Table 6 (p. 193).
Specimens examined. 1. BRAZIL. Goias: Barro do Rio Sao
Domingo, 1 (CNHM).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 175
Genus Eligmodontia F. Cuvier
Eligmodontia F. Cuvier, 1837, Ann. Sci. Nat., Paris, Zool., (2), 7: 168. Thomas,
1916, Ann. Mag. Nat. Hist., (8), 17: 140- included species: typus Cuvier,
type [elegants Waterhouse a synonym), hirtipes Thomas, moreni Thomas,
morgani J. A. Allen.
Elygmodortia Wiegmann, 1838, Arch. Naturg., 4: 388 misprint.
Heligmodontia Agassiz, 1846, Nomencl. Zool. Mamm., Addenda, 5, Index
Univ., pp. 136, 175 emendation.
Elimodon Wagner, 1841, Arch. Naturg., 1: 125 misspelling. Palmer, 1904,
N. Amer. Fauna, no. 23, p. 256 "Elimodon," cited from Fitzinger, 1867.
Eligmodon Thomas, 1896, Ann. Mag. Nat, Hist., (6), 18: 307 emendation.
Type species. Eligmodontia typus Cuvier.
Included species. Eligmodontia typus Cuvier.
Distribution
Figures 27, 45
From the Straits of Magellan northward through Magallanes
Chile into Argentina as far as the Rio Parana on the east, and
along the Andes on the west into northern Chile, and the Lakes
Poopo and Titicaca drainage basins of western Bolivia and extreme
southern Peru; altitudinal range, sea level in southern latitudes, to
more than 4500 meters above in higher latitudes.
EXPLANATION OF FIGURE 45
Eligmodontia typus: collecting localities and collectors.
Type localities in boldface.
Eligmodontia typus puerulus (1-12; 36-38)
CHILE (1-3)
1. Churiguaya(?), Puna Zone, Tarapaca. Presumably in vicinity of Parina-
cota; G. Mann.
2. San Pedro, 20 miles east, Antofagasta. - C. C. Sanborn at 12,600 feet.
3. San Pedro de Atacama, Antofagasta (3223 meters). F. Philippi.
BOLIVIA (4-6)
4. Oruro, Oruro. P. O. Simons at 3700 meters.
5. Challapata, Oruro. P. O. Simons at 3750 meters.
6. Pampa Aullagas. P. O. Simons at 3800 meters.
ARGENTINA (7-12)
7. Abrapampa, Jujuy. E. Budin at 3500 meters.
8. Chorillos, Los Andes (=Salta). -E. Budin at 4500 meters.
9. Corral Quemado, Catamarca. E. S. Riggs.
10. Chumbicha, Catamarca. E. Budin at 600 meters.
176 FIELDIANA: ZOOLOGY, VOLUME 46
11. Chilecito, La Rioja. F. P. Moreno at 1200 meters.
12. Media Agua, San Juan. L. E. Miller and H. S. Boyle at 2200 feet.
PERU (36-38)
36. Santa Rosa, Puno. 0. P. Pearson at 14,000 feet.
37. Moquegua. O. P. Pearson.
38. Tacna. 0. P. Pearson.
Eligmodontia typus typus (13-35)
ARGENTINA (13-34)
0. Corrientes, Department. Supposed type region, but genus may not occur
here.
13. Delta del Parana, Buenos Aires.
14. Bahia Blanca, Buenos Aires. C. Darwin.
15. Peru Station, F.C.O., La Pampa. F. H. F. Parkes.
16. Pichi Mahuida, La Pampa. E. Budin at 650 meters.
17. Chos Malal, Neuquen. E. Budin at 800 meters.
18. Agrio (Rfo), Neuquen. J. Yepes.
19. Zapala, Neuquen. E. Budin at 1062 meters.
19. Las Lajas, Rfo Agrio, Neuquen. E. Budin.
20. Choele-Choel, Rio Negro. E. Budin.
21. Pilcaniyeu, Rio Negro. H. E. Box; E. Budin.
22. Huanu Luan, Rio Negro. J. C. Peters.
23. Rfo Chubut, Chubut. C. Burmeister.
23. Rawson, Chubut. E. Budin.
24. Pico Salamanca, Chubut (=Comodoro Rivadavia). E. Budin at 100
meters.
25. Piedra Clavada, Rfo Deseado, Santa Cruz (=Comodoro Rivadavia).
E. Budin at 200 meters.
26. Swan Lake, Santa Cruz. A. E. Colburn.
27. Upper Rfo Chico, Santa Cruz. A. E. Colburn.
28. Arroyo Else, Santa Cruz. Used incorrectly for "Basaltic Canyons" (<?..).
28. Basaltic Canyons, Santa Cruz. Not precisely located, said to be "50 miles
southeast of Lake Buenos Aires," but the Cordon Basaltico is at the point
shown on map; A. E. Colburn.
29. Rfo Chico, Santa Cruz. C. Burmeister.
30. Santa Cruz, Santa Cruz.
31. Coy Inlet, Santa Cruz. O. A. Peterson.
31. Rfo Coy, Santa Cruz. O. A. Peterson.
32. Halliday Ranch, Santa Cruz. O. A. Peterson.
33. Cape Fairweather (=Cabo Buen Tiempo), Santa Cruz. 0. A. Peterson.
34. Rfo Gallegos, Santa Cruz. E. Budin at 50 meters; 0. A. Peterson.
CHILE
35. Sarmiento (Lake), Ultima Esperanza. C. C. Sanborn.
Eligmodontio typus puerulus
typus
FIG. 45. Collecting localities of subspecies of Eligmodontia lypnx. See opposite-
page for explanation.
177
178
FIELDIANA: ZOOLOGY, VOLUME 46
FIG. 46. Eligmodontia typus. Dorsal and palatal aspects of skulls, showing
variation in size (Xl^)-
Characters
External. Small, gerbil-like in size, limb proportions, color and
long, silky texture of pelage; upper parts buffy to tawny with a fine
mixture of blackish giving a sandy effect in some series; under parts
white, the hairs wholly white or plumbeous basally; tail from about
15 per cent shorter to about 15 per cent longer than combined head
and body length, the pale under side from sharply to hardly defined
from darker upper side; tip without conspicuous brush; hind legs
elongated, metapodials broad, outer digits long, first hind toe without
claw hardly extending to base of first phalanx of second, fifth toe
without claw extending to base of second phalanx of fourth toe,
claws well developed; soles (fig. 3) hairy except on tips of toes, first
postdigital and tarsal tubercles; middle postdigital tubercles fused
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 179
FIG. 47. Eligmodontia typux. a, b, palate; r, skull; d, mandible.
to form a hairy cushion; fifth postdigital tubercle obsolete or ab-
sent; ears well developed but their length from notch always less
than that of hind foot, small white postauricular patches present or
absent; mammae, 2-2=8.
Cranial (figs. 46, 47). Skull delicately built, dorsal contour flat-
tened anteriorly, convex posteriorly, rostrum slender, its greatest
width subequal to, usually less than, width of mid-frontal region;
upper surface of skull with shallow median longitudinal depression;
sinusoidal inflations of frontals reduced; sides of supraorbital region
divergent, the edges square, never beaded or raised ; outline of fronto-
parietal suture crescentic to nearly straight, never angular; brain-
case broad, smooth; interparietal well developed transversely, about
180 FIELDIANA: ZOOLOGY, VOLUME 46
five times wider than long; zygomata delicate, parallel-sided and
little expanded; anterior border of zygomatic plate plane or slightly
concave; bony palate produced well behind posterior plane of last
FIG. 48. Eligmodontia typus. a, right upper molars; b, right lower molars.
molars; postero-lateral palatal depressions shallow, each marked by
a conspicuous pit; a pair of anterior palatal pits present, one on each
maxillary bone behind posterior end of incisive foramen; width of
mesopterygoid fossa at anterior base of pterygoid processes usually
less than greatest length of m^ and about one-half width of parap-
terygoid fossa measured at same plane; parapterygoid fossa com-
paratively shallow and broadly expanded laterally; bullae moderately
inflated, length, less tubes, equal to or longer than alveolar length
of molar row; mandibular ramus deeply excised posteriorly; condy-
lar process about twice length of coronoid process and extending
posteriorly to vertical plane of tip of angular process; capsular pro-
jection situated posteriad to angle of sigmoid notch.
Dental (figs. 48, 49). Upper incisors opisthodont, ungrooved,
molar rows parallel-sided or convergent posteriorly; upper and lower
first molars four-rooted; m ? slightly more than one-half length of m^;
cusps high, arranged in echelon, those of upper molars ovate, of
m T _s tending to triangulation; mesostyle(id) absent; m^ without
mesoloph and tending to lamination; m 7 sigmoid in outline; upper
and lower first molar with anterior fold well developed in unworn
condition, weak or obsolete when worn; m 5 ^ with anteroloph, the
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 181
first primary fold well developed, never becoming an enamel island
in m-, rarely an island in worn m-; second secondary fold indicated
FIG. 49. Molar planation. o, crested in Zygodontomys; b, bilevel crested
in Eligmodontia; c, plane in Phyllotis amicits.
only in unworn m-^ a ; first minor fold weakly developed or obsolete
in m% obsolete in m :i ; procingulum of m 2 _u rudimentary or absent;
minor fold present as a notch on enamel wall of m 2 , as a minute
enamel island in unworn m 7 ; second primary fold well developed
and persistently open in m r _ 5 , obsolete in m 7 .
Comparisons
The pale long silky pelage, long thin hind legs, and spade-shaped
hind feet with a large hairy cushion on each sole, are salient external
characters distinguishing Eligmodontia from all other living crice-
tines. Some of the Old World gerbils, notably Gerbillus (s. s. ), are
strikingly similar to Eligmodontia in size, bodily proportions, color
and texture of pelage, and modification of the hind feet. In con-
trast, the closely related Piura desert mouse, Phi/llotix gerbillnx, is
less similar superficially; its hind legs are not elongated, and the
three middle postdigital tubercles are discrete and bare.
182 FIELDIANA: ZOOLOGY, VOLUME 46
Cranially, Eligmodontia is nearest Calomys and most like C.
laucha. The former is distinguished from the latter by such relative
characters as longer rostrum, slightly more inflated braincase, fron-
tals with little or no sinusoidal inflations, more pronounced dorso-
median longitudinal sulcus, less arched zygomata, and fronto-parietal
sutures with less curvature.
The bilevel-crested, pre-terraced molars of Eligmodontia are an-
nectant between the crested molars of Calomys and the terraced and
plane molars of Phyllotis (fig. 49). Internal folds retained in some
individuals of Calomys and mesostyle(id) usually present in Zygo-
dontomys, are absent in Eligmodontia.
Remarks
Eligmodontia is the most highly specialized member of the Calo-
mys section. Its ecological niche in the New World parallels that of
Gerbillus in the Old World. Morphologically, Eligmodontia bridges
the narrow gap between the Calomys and Phyllotis sections of phyl-
lotine rodents.
Habits and Habitat
The capture of the type specimen of Mus elegans (= Eligmodontia
typus) is described as follows by Charles Darwin (in Waterhouse,
1839, p. 42) : " 'Whilst bivouacking one night on shore, amongst some
sand hillocks, this mouse, with its tail singed, leapt out of a bush
which was placed on the fire. Its hind legs appeared long in propor-
tion to the front, and it did not appear to be very active in endeav-
ouring to make its escape.' ' Thomas (1898a, p. 210) has recorded
Henry Durnford's observations on two specimens of Eligmodontia
captured in Chubut, Argentina. The first is said to be " 'not un-
common among bushes, into which it climbs readily. Comes out in
the evening to feed. I do not think this species makes holes in the
ground.' ' The second specimen bears this notation: "like the long-
tailed rat [Phyllotis griseoflavus] this species is most numerous in the
summer, though during the winter a few may be found. It does not
enter the house like its large relative, but is extremely numerous in
the thick scrub and brushwood in the neighborhood of the Colony,
and universally distributed. It makes a small oval nest of fine grass
and any soft material, which it places in the center of a thick bush.
It never burrows in the ground, but is extremely numerous among
the thorn bushes." During the course of their journey across the
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 183
Gobernacion de Santa Cruz, Argentina, the Birabe'ns (1937, p. 160)
found a nest of the mouse under a rock on the sea shore between
San Julian and Bahia Laura. The nest was made of bits of sponge
thrown up by the sea. Emilio Budin"(m Thomas, 1919b, p. 202),
who collected the same species in Pilcanieu, upper Rio Negro, re-
ports it as "common. Lives in holes at the foot of the bushes."
The same collector referred to another specimen, the type of jacunda
Thomas (1919d, p. 131), as having been "caught in sandy soil. In-
habits deserted burrows of Tuco-tucos [Ctenomys]." Budin took the
type series of marica Thomas (1918, p. 483) among pencas, translated
by Thomas as "prickly pears" but which are probably some species
of maguey. Food in stomachs of Eligmodontia of northern Chile,
examined by Mann (1945, p. 75), consisted largely of beetle larvae,
with only a small fraction of vegetable matter.
Evidence from morphology, distributional records, and field obser-
vations indicates that Eligmodontia prefers a sandy or rocky terrain
dominated by xerophytic plants. Because of the disproportionate
length of fore and hind legs, the mouse walks clumsily on the ground
and climbs slowly through brush. The long hind legs, however, per-
mit the animal to accelerate its progress by bounding over level
ground and leaping from rock to rock or among the branches and
thick leaves of bushes. According to testimony, the mouse nests in
shrubs, spiny bushes, and sometimes, whether for nesting or only for
temporary asylum, in burrows not of its own making.
Eligmodontia typus Cuvier. (Synonymy under subspecies.)
Distribution and characters. As for the genus.
Variation. Dark and pale color phases are more sharply marked
in Eligmodontia than in most other phyllotines. Nearly all Eligmo-
dontia of the pampas and Patagonia of Argentina and Magallanes,
Chile, are dark. The oldest name for them is E. typus Cuvier. Mice
of the dry salares and punas of northern Argentina, northern Chile,
and southwestern Bolivia average paler because of the greater num-
ber of pale phase individuals among them. The name E. typim
puerulus Philippi is available for them.
Individual variation in size is striking. Under parts vary from
wholly white to white with basal portions of hairs dark gray. As a
rule, the more white on the under parts the greater the extension of
white over lower half of sides of trunk, thighs, and arms. Pallid tails
are usually correlated with pale bodies, but the difference in color
184 FIELDIANA: ZOOLOGY, VOLUME 46
between upper and lower surfaces of tail varies independently.
Most variation in cranial characters is correlated with gross size
differences. The rostrum, however, tends to be narrower and more
tapered in some individuals and populations than in others. The
shape of the anterior border of the zygomatic plate varies individ-
ually from straight to concave.
Eligmodontia typus typus Cuvier
Eligmodontia typus Cuvier, 1837, Ann. Sci. Nat., Paris, (2), 7: 168, pi. 5 (ani-
mal, skull, molars, alimentary tract). Lesson, 1842, Nouv. Tabl. Reg.
Anim., Mamm., p. 133 part, elegans Waterhouse in synonymy. D'Or-
bigny and Gervais, 1847, Voy. Amer. Merid., 4, Mamm., p. 24 ARGEN-
TINA (type from Corrientes). Allen, 1905, Exped. Patagonia, Princeton
Univ., 3, Mamm., p. 51 elegans Waterhouse in synonymy. Marelli,
1924, Elenco Sist. Fauna Prov. Buenos Aires, p. 670 ARGENTINA:
Delta del Parana. Thomas, 1926, Ann. Mag. Nat. Hist., (9), 18: 636
ARGENTINA: Neuquen (Chos Malal; Las Lajas; Zapala). Thomas,
1927, op. cit., (9), 19: 652 ARGENTINA: Neuquen (Zapala). Thomas,
1927, op. cit., (9), 20: 204 ARGENTINA: Neuquen (Pichi Mahuida).
Yepes, 1939, Rev. Centre Doc. Estud. Cienc. Nat., 2, (5): 9 ARGEN-
TINA: Neuquen (Rfo Agrio).
E[ligmodontia] typus, Giebel, 1855, Odontographie, p. 51, pi. 23, fig. 10 (den-
tition). Thomas, 1918, Ann. Mag. Nat. Hist., (9), 2: 483 "elegans is
always assumed to be synonymous." Thomas, 1929, op. cit., (10), 4: 39
ARGENTINA: Corrientes (type locality); typus for northern form,
elegans for southern.
Mus elegans Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 19 ARGEN-
TINA: Buenos Aires (type locality, Bahfa Blanca). Waterhouse, 1839,
Zool. Voy. "Beagle," pt. 2, p. 41, pi. 12 (animal), pi. 34, fig. 2 (skull,
molars) description; comparisons; identification with typus Cuvier.
Mus (Cal[omys}) elegans, Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 21.
Hesperomys elegans, H. Burmeister, 1879, Descr. Phys. Rep. Argentine, 3:
220 ARGENTINA: Chubut (Rfo Chubut).
H[esperomys] elegans, C. Burmeister, 1891, Anal. Mus. Nac. Buenos Aires,
3: 314 ARGENTINA: Santa Cruz (Rfo Chico).
H[esperomys Calomys] elegans, Thomas, 1884, Proc. Zool. Soc. London, 1884:
449 classification.
E[ligmodon] elegans, Thomas, 1896, Ann. Mag. Nat. Hist., (6), 18: 308
synonym of E. typus.
Eligmodontia elegans, Thomas, 1898, Proc. Zool. Soc. London, 1898: 210
ARGENTINA: Chubut; habits. Thomas, 1929, Ann. Mag. Nat. Hist.,
(10), 4: 39 ARGENTINA: Chubut (Pico Salamanca) ; Santa Cruz (Piedra
Clavada; Rfo Gallegos); synonyms, E. morgani Allen, pamparum Thomas.
Yepes, 1939, Rev. Centro Doc. Estud. Cienc. Nat., 2: 5 ARGENTINA:
Neuquen (Chos Malal). Gyldenstolpe, 1932, K. Sv. Vet. Akad. Handl.,
11: 70, 162, pi. 7, fig. 3 (skull), pi. 17, fig. 19 (molars) ARGENTINA:
Rio Negro (Pichi Mahuida).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 185
Eligmodontia morgani Allen, 1901, Bull. Amer. Mus. Nat. Hist., 14: 409
ARGENTINA: (type locality, "Arroyo Else, Patagonia"). Allen, 1905,
Exped. Patagonia, Princeton Univ., 3, Mamm., p. 53, pi. 9, fig. 1 (skull),
pi. 10, figs. 2, 3 (molars) ARGENTINA: Santa Cruz (type locality,
"Basaltic Canons, 50 miles southeast of Lake Buenos Aires, Patagonia,"
not "Arroyo Else" on the labels and in the original description; Rfo Galle-
gos; Halliday Ranch; Coy Inlet; Cape Fairweather; upper Rfo Chico;
Basalt Canons; Swan Lake). Thomas, 1916, Ann. Mag. Nat. Hist., (8),
17: 141 classification. Thomas, 1919, Ann. Mag. Nat. Hist., (9), 3: 202
ARGENTINA: Rio Negro (Pilcaneu). Birabe'n and Scott, 1936, Rev.
Mus. La Plata, (n.s.), sec. oficial 1936, p. 160- ARGENTINA: Santo
Cruz (coast). Cabrera, 1936, in Birabe'n and Scott, loc. cit., perhaps a
subspecies of E. typus.
Eligmodontia elegans morgani, Osgood, 1943, Field Mus. Nat. Hist., Zool. Ser.,
30: 199 ARGENTINA: Santa Cruz (Piedra Clavada; Rfo Coy; Rfo
Gallegos); CHILE: Magallanes (Lake Sarmiento, Ultima Esperanza).
Eligmodontia morgani pamparum Thomas, 1913, Ann. Mag. Nat. Hist., (8),
12: 572 ARGENTINA: La Pampa (type locality, Peru Station, F. C. O.).
Type. Presumably in the Museum National d'Histoire Naturelle,
Paris; collected by Alcide d'Orbigny.
Type locality. "Buenos Aires," but according to d'Orbigny
(supra cit.) "province de Corrientes," Argentina. The "Buenos
Aires" locality, as given in the original description by Cuvier, was
meant to encompass most of central and northern Argentina, includ-
ing Corrientes. There is a question of whether or not the genus
actually occurs in the modern department of Corrientes or anywhere
north and east of the Rio Parana.
Distribution (map, fig. 45). Southern Chile and Argentina, from
the Straits of Magellan north through Magallanes, Chile and in Ar-
gentina into the provinces of La Pampa and Buenos Aires. Occur-
rence of Eligmodontia north and east of the Rio Parana has not been
corroborated and its existence there is extremely doubtful.
Characters. A sandy-colored mouse, sides slightly paler than
upper parts, except for a narrow, not always well-defined, ochru-
ceous lateral line; tail brown above, nearly as dark below, or sharply
bicolor.
Taxonomy. In his description of elegans, Waterhouse made it
clear both in text and synonymy that his specimen and Cuvier 's
typus "are identical." The synonymy was pointed out again by
Thomas, first in 1896, then in 1916, 1918, and finally in 1929. J. A.
Allen, in 1905, also called attention to the priority of the name typnx
Cuvier, published March 1837, over that of elegans Waterhouse, dated
November 21, 1837. Nevertheless, Allen added morgani and Thomas
186 FIELDIANA: ZOOLOGY, VOLUME 46
added pamparum, both names later shown by Thomas himself (supra
cit., 1929), to be synonyms of the synonym elegans.
Measurements. See Table 7 (p. 194).
Specimens examined. 19. ARGENTINA. Rio Negro (Pilcani-
yeu, 1 (CNHM) ; Huanu Luan, 1 (CNHM) ; Choele-Choel, 3 (CNHM,
1; MACN, 2). Neuquen: Chos Malal, 3 (CNHM); Las Lajas, 1
(CNHM) . Chubut: Rawson, 2 (MACN) . Santa Cruz: Santa Cruz, 3
(CNHM); Piedra Clavada, 1 (CNHM); Rio Gallegos, 1 (CNHM);
Cabo Buen Tiempo (Cape Fairweather), 1 (CNHM); Rio Coyle
(Rio Coy), 1 (CNHM). CHILE. Magallanes: Lake Sarmiento,
Ultima Esperanza, 1 (CNHM).
Eligmodontia typus puerulus Philippi
Hesperomys puerulus Philippi, 1896 [sic], Anal. Mus. Nac. Chile, Zool. Ent., 13a,
p. 20, pi. 7, fig. 1 (animal).
Mus puerulus, Philippi, 1900, Anal. Mus. Nac. Chile, Zool. Ent., 14a, p. 60.
Eligmodontia puerulus, Osgood, 1943, Field Mus. Nat. Hist., Zool. Ser., 30:
198, fig. 27 (skull) CHILE: Antofagasta (San Pedro, 20 miles east);
redescription of type.
E[ligmodontia] p[uerulus] puerulus, Mann, 1945, Biologica, Univ. Chile, fasc. 2,
p. 78 (comparisons).
Eligmodontia puerulus puerulus, Pearson, 1957, Breviora, Mus. Comp. Zool.,
Harvard, no. 73: 2 PERU: Moquegua; Puno; Tacna; altitudes, 13,000-
15,300 feet.
Eligmodon Moreni Thomas, 1896, Ann. Mag. Nat. Hist., (6), 18: 307
ARGENTINA: La Rioja (type locality, Chilecito, 1200 meters altitude).
Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141 classification.
Eligmodontia typus morenoi, Cabrera, 1961, Rev. Mus. argentine Cienc. Nat.
"Bernardino Rivadavia," 4: 482 classification.
Phyllotis hirtipes Thomas, 1902, Ann. Mag. Nat. Hist., (7), 9: 225 BOLIVIA:
Oruro (type locality, Challapata, Lake Poopo, 3750 meters altitude;
Oruro; Pampa Aullagas).
Eligmodontia hirtipes, Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141
classification.
Eligmodontia puerulus hirtipes, Mann, 1945, Bioldgica, Univ. Chile, fasc. 2,
p. 78 classification; comparisons. Pearson, 1951, Bull. Mus. Comp.
Zool., 106: 142 PERU: Puno (Santa Rosa).
Eligmodontia marica Thomas, 1918, Ann. Mag. Nat. Hist., (9), 2: 483
ARGENTINA: Catamarca (type locality, Chumbicha, 600 meters alti-
tude). Thomas, 1919, op. cit., (9), 3: 115 ARGENTINA: Catamarca
(desert area east of Chumbicha).
Eligmodontia hirtipes jacunda Thomas, 1919, Ann. Mag. Nat. Hist., (9), 4:
131 ARGENTINA: Jujuy (type locality, Abrapampa, 3500 meters
altitude).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 187
Eligmodontia puerulus tarapacensis Mann, 1945, Biologica, Univ. Chile, fasc. 2,
p. 75, fig. 25 (feet), figs. 26, 27 (alimentary tract), fig. 28 (zygomatic plate),
pi. 28 (skin) CHILE: Tarapacd (type locality, "Churiguaya" puna zone).
Mann, 1950, Invest. Zool. Chilenas, 1, (2): 5 CHILE: Tarapacd.
Type. Skin, mounted, Museo Nacional de Chile; collected by
Federico Philippi between 1884 and 1885.
Type locality. San Pedro de Atacama, Antofagasta, Chile; alti-
tude, 3223 meters above sea level.
Distribution (map, fig. 45). Sierras Pampeanas and Andes of
northern Argentina from the province of San Juan northward into
the puna zones, lake, and salar basins of western Bolivia, north-
western Chile and extreme southern Peru; altitudinal range from
approximately 500 to 4800 meters above sea level.
Characters. Slightly paler throughout than typus; back less
mixed with blackish, tail pale brown or grayish above, paler be-
neath, to nearly uniformly whitish.
Remarks. The original publication of the name Hesperomys
puerulus Philippi is dated 1896. However, the bibliographic sec-
tion for 1894 of the Archiv fur Naturgeschichte (1896, Jahrg. 62, 2:
234) records the date of publication as 1890. Whatever the date,
the name puerulus clearly has priority over moreni, described by
Thomas in October 1896.
According to Osgood (supra cit.) the type of puerulus, in the
Santiago de Chile Museum, is "not so brightly ochraceous as in
Philippi's figure, and is more of a pale buff with a cinnamon-tipped
effect. On the under side . . . the hairs are white to the roots on the
throat, chest, inguinal region, and probably along middle line of
abdomen. Laterally on the abdomen, the hairs have light grayish
plumbeous bases. The soles of the hind feet seem to be hairy, but
this is not well ascertained. Hind foot measures 21.5 [presumably
with claw]. The tip of the tail is not quite perfect, but apparently
it was slightly pencilled.
"The small size of the hind foot in the type is the only feature
to cast any doubt upon its identity with the small series now at hand
in which the foot measures 24, 25, 25, 25, and 26 mm. Other char-
acters of the type, especially the pure white under parts and general
proportions, seem to outweigh this, and with a series from the type
locality showing these characters, the establishment of the name is
amply justified."
The five specimens mentioned above by Osgood are from Rio
San Pedro, 3940 meters above sea level, and 20 miles east of San
188 FIELDIANA: ZOOLOGY, VOLUME 46
Pedro, a station on the Antofagasta-Bolivian railroad. The locality
is in the puna zone about 115 kilometers north of San Pedro de Ata-
cama, where the type of puerulus was taken. The specimens, all in
dark phase, are insignificantly paler, especially on the tail, than
Argentina typus.
The northern Chilean form described as Eiigmodontia puerulus
tarapacensis by Mann is said to differ from Philippi's puerulus by
paler color of dorsum and bicolor tail. The tail of the type of pueru-
lus is shown in the original figure to be sharply bicolor, hence as in
tarapacensis. Tails in the Rio San Pedro series vary from sharply
bicolor to faintly so. Color of back is the tenuous character that dis-
tinguishes pale from dark phase individuals.
Thomas described moreni as "most nearly allied to E. elegans,
Waterh. (E. typus, F. Cuv.)," but larger, with longer feet and
heavier muzzle. Thomas qualified, however, that the type of elegans
is "a bleached and deteriorated skin and all the examples of the
new form [moreni] being in spirit, it is impossible to compare them
satisfactorily." Two specimens from Media Agua, San Juan, south
of the type locality of moreni in Rioja, are like pale phase repre-
sentatives of typus, on the one hand, and agree completely with the
description and figure of puerulus, on the other. Eiigmodontia
marica Thomas is also pale and was first characterized as the smallest
"species" of the genus. Of the four original specimens obtained
by Budin, measurements of only the type of marica are given. The
dimensions indicate either a Juvenal or very small adult otherwise
not distinguishable from other Eiigmodontia within the range here
assigned to puerulus. The pale hirtipes Thomas from the arid region
about Lake Poopo was first described as a PhyUotis and compared
with African jumping mice of the genus Gerbillus. Thomas described
jacunda as a subspecies of hirtipes on the basis of its being "greyer
and duller." Of two specimens at hand from Chorillos, Los Andes,
south of the Jujuy type locality of jacunda, one is as pale, with
tail nearly all white, the other is an ordinary dark phase individual
with sharply bicolor tail.
Measurements. See Table 8.
Specimens examined. 10. ARGENTINA. Los Andes: Choril-
los, 2 (MACN). Catamarca: Corral Quemado, 1 (CNHM). San
Juan: Media Agua, 2 (AMNH). CHILE. Antofagasta: Rio San
Pedro, 20 miles east of San Pedro, 5 (CNHM).
"3 J3 COw> ~Ztt*f'*f e ^~Z-*f'*f'*r r
eoco-^rTCOcocococococococo I COCOCOCOCOTCOCOCOTCOCOCO
. cooo^^i- o ~
co' co' co' co' i 'ti
7 ,w ^
o 10 oo <^ ^ ^ t~" *o~ o ^ ^ "* ~ "
c~ o> 10 o co co cooTt-{i-ioo'cM ccTcot>-coco'io'co'O'-<cocoooc^
, I ^H i-H i-H -H i-* 1 I I i-H -H I i-H -H | * I 1-H ^^ * li lr~ l (^H* *-^, 1,^4*.^ N Q^
C 'C
N s
^ "5 OS
oo ^ -^ o t- ^ ^ co oo o o
Srtjs -^ ^idcdio'^^io'ioco tti
O ti bfl * ' I ^i i, [/; "5^.
F* ^^ jj [* ^^ oo co c^i *""* co t"~ co ^1* co ^*' ^' ^* ^^ ^i
E*z3~ co OJco' oi ri<cococo^<^Ti<cococo
CM^co^^^|^cococococoi^i"'^"'t'T)<'i<'t'a<'r'o'-rioco-r <r.
"WCMCM ICMCMCMCMCMCM ICMCMCMCMCMCMOJCMOIOICMIMOI s
>o
CO , v Cj ^T
oo ^-i 05 ^ oo t- ^
a hTs 8 ?^ T i S" s
^* t> oo "5 ^^t~ oo c- t> t- S cs
- - 1 > - | Ci- lo .d' T ^'^'- | Ct "^"^QC!^
I I tf oooo -2 -g ^
o. * !?
oo co o
3 oo o i i i i - - c-i <M 01 _ ^ . f-i
ST- 1 i ICM rt CM , i cvj s IT! CM CM c-i .
^ II CM i S? 1 1 CM IM i i i W 2 *rf S
C ff * r*\
~. ~. I lOOt'-O'Jt OSOJOOiOOOOOOCS' IO> "j^'^'^iOiOi ""'C O)
"c^-o^ N ^ N "I ISJ I
U 00 CO T)<r- li It |O>O| it-lO ^ H U
ja ~ toco -Tfoo^-^O'TOi o>*~ljj"rt-a
H co OO i iooocoo^'t-r^j-r^'O
- t~ oo t 60 t^ O^ t~ t "O v. 'C J<
" - * ' '' rt ea o < f -
" J I o-
I-H i o i iOi*O 10 ^ -1 *->'
oo co co ^^ - , 100^* ^ ^H ?.. -O
i m * ^ f~* on ^i ^ O (f^ rt ^ rt ^
C-l
-cajosooa>ooooo>'-iooQOooo>ooiooooooooajOioi-Ht^
> ? G3
TS 5 s P
II ijlr -* '
189
"* g
c3 3
O ^
I- 6
^
C^J
i-HCO
10
10
o ;*
^o
i
CO
CO*
coco
oq
co
P
CO 2
: -^
CO
COU3
1
^ S
OO ^f
CO
'S
"3
CO
co co
CO
co, N ~
M* ^
cS
2
CO CO Tf CO t-
t- 10 t- co * Tf c>
ncO^o'cOT}'
US
co' ob
oq
T3
.2
co co co co co
co co co co co co c*
D CO CO CO CO
co'
co IM'
CO g
"3
a
CO
'c
'Sfi
c"
^4
i-HCO
IO
1O
o
'C *"
, s
,, ^
J
o.2
*^
CO
C~* CO
S"
t-
,_*
r-5 co
(^J
I
SB
c
1 1 1 1
1 I
11
o -
u
i
1 1
1
o
i
H w
. CO
C &
(
(~^ J_^
]
* TJ*
"? "o
C/TT3
"C ^
i i
1-1 1 1
1 I
IH o^
oi o
^
CO 5^
Tf <* t>CO OO CO
i-H Tjeo const-
- 00 lOO IM
o
co' 06"
CO N
C
COrHrHrH COrH
COCOrH 1-HrH,-
HO -HC^CO
c<i
r-5 o
rH O
Ji'S
""* 'So
S
'E
g
t
1-1 co
U5
U5
^l"
.f") Q
S
T?^?
^
P
00
2
Ct3
'
i5 c<i
Tj5
'
i (
"t^ *^H
^j
CO
iM (M
c^
OJ
^^
O *
p^d 4-5
1
1 1
1
1
CO
rrt
a c
CO
Tjl t-
oq
co m
C-"
*S P
2
i5
O5O
TH
t-'
CO g
S
^ c
CO
i 1 OJ
(M
" s ^ r^
c
cocooo co o
CO U5 CO CO O CO U
SCO (M t-OO
^
oo" co""
TjT
^ SE-"
<V g
(M O I-H TH COCO
co TJ< o co rH TH c
5Oi-H iM I-H
CO
o oo
rH r .
L^ CO
CO CO CO CO CO C<
(M CO (M (M <M (M C-
J <MC<1 (M<M
<M
CO 1 "^
05 g
Lj ^
o
^H ?*
1 S
us t;
^
c3
00
co
oo^ .g
"3 ^^
i-P
s
rj D,
_
rH
|
oo *
cS -u *S
cU g
o
r c
H y
8f O
H Q 0)
t-l ^
.
-g P<
a>
s a.3
~ ^
s w
>c
o
S
^
03
I
.
^ 13
^_, & I I I I I co^usiovo^col
O H I I I I I TH rH TH rH TH rH TH [
.2
a> -u o
2 '~ l "^
.fi t Jis''- | i- 1 ^-Tf~~"''t^ h *''-'T3 .S"-^
iO Q5 i i O CD **i *^ ^ ' *
3T37 ^,0*0^7,2 M g >&.& >>
S .S co oo ^.^ oo co I f c rtCO'C a>^
gS ^t^oo opS r Q <1 i ) '3 ||
t^ FHCO 05U3rH OrH||"fecO'3gS.J-3
TJ< Tj- TJ. >. t- 2B,LL" 3 -So2 Xffi
o -^
OOCOTf"O5U3COCOO5"500lOt-CO"2
rHOOOOO5CDOOt-OOOOC-C-t-OOC~O5
a .- o> o
rr 4-> O. *-
r Sau
S C 3
00 t> tD 5 t _
co co co co co
wee
co w w co w co
co
co
O
j=
H
t-;
oo eg'
eg co eg -H
eg CM eg eg eg ^H
S
3
DC
eg eg eg eg eg eg
s
-i o w o
Oi t^ oj oo oo
os
o*co
-HCOIO TO* to
-c.5
II
a
I'
Sc
o o
s.s-.s-^
sbs.^
'C S'C c
~0 %
c 8
|c-1-
- . ^ 3
: . . -a
rt O_bC S
ll!s
H^|
2 2t c
0.0 rt-
^ E
Sa
*- Crs *
o -"2 c
O B - O
TI is s
3| w
s. ^
^ gwK^OOft, .= 5 OOJJ jj c;
'C OH ? CO e, <
191
o s^;
a
S -
Oo ira CD kO -_ OS O
-C *" "*" ^ 1*"? T* ^ *?
ti c3 o eo" T}<
CO C5 g\j ^
4 1
H
-f ,^ ^
^ ^ Tj< X
I ^_-
5)<
" co co" co T-H 1-4*1 1 10 i-
-1 CO CO -^ CO M5 Co"i-l T
t- co Tf co
CO
co
Tj< T)< C
& c
o
_w o'
o co" ^
? CO C r! .
"j r* 50"
Oj 4J 1 I "^
Tf Tj< . U3 1
i-H i 1 i i 1
5 358
g-0 1 ^
g > *-<
rH CO r-T *
1 oo_ *C & _a,
bfl I* CO r-T
co co -^i a
j C
^ M S fi
4 t
-H OJ W ^
oo'i-i oo co 10" c
j us co c- i-Tco a
-^ >
*' ~j Q^ W
-* <* <*' -* o
310 CO C00 -.tflO^-f
^* ^* 03 ^"2
1
o c.Sf'S)
-jj ^* CO ^* 05 C"O O "J^
d) T-H
O t- ,-.
5 1
S - w
g x gj co t: t: ^ o? 2? P S S
CM co CO ^
j <;
SCO
bo |f I-H oo*
s-_ * ._
t^ O CO O
(
D co"**^- *"
_r^; cd co #
^J* CO b T
' <
^ rt a3 co
SSi oo*
CO_^ CO CO O
i S
3 C M 2
^rf COCO t~ 00 CO CO CO CO IO O OS CO OS CO O O OO i
-H ^ S
CO t- CO t> OO IO CO U
3OSCO CO COO5 COOOC-
- t> IO !
oi 2
CM (M CO (N (M (M C
3 CO CO CO CO CO CO CO C
1 CO CO C
"* ' OH ^
^* S2 co
" w ^
o
S .2 2
r% 1 0* * 1 *
s oo | oo 06" oo
os t~
jv S 8 s
CO jji SJ ^
W 1 1 i-H I
H i 1 | i 1 1 1 1 1
1 1 1 1
'~~ ) 1 ~~
-. O t4_|
o m o
4J ^-^ ft^ ^. i
UJ
CD a <u
O ,x
S
a >. a
O W
1O CO ... U
9
"- 1 CVI J]
co co } c-
1
r . * K ^
ft \ *^
1 ^
L "" "* ^
c '"^ c<T i
O5 O CO *
H
M to
j-- 2ico_ l_
i i co co co
]
. C .
W i-Hi-7 COi-HOOIC
5i-l| COOSCOi-H OCOC
J CO
^ c o c
(M C^J (M CO W CO 1 C
JCOl COi-HCOCO (MCOC
J CO CO
c^ 5-^3 o
a us
^0,'C .&
CO Tj<
H
X ^
s"
w J
1 ^ f-^
o" o" ,., c
>
O ^3 fl)
'S3 oo
O5 O5 2^1-
H
^O *^3
WJ
t cC j
^^ 7
00 U5 ^H C
1
rt fi ctf
t^,oo_
,!>. t^ 05^ t;
.S 'B .S
O IO~ OO CO lO^CO 1 C
^ o o ^o T^ t^ oo oo o
3^0 10
CO bO'C bo
oo t- t- oo co t~ 1 c<
sos oooooot- t-ooa
3 00 CO
'C o 'C
o _, o
g
^ r 51 2
H S
CO .
^~*. co
V
o J~ o
-0 ^^
C 1 1-1
CO I-H JO w **1 10" **1
^i CO CO
lo co" ^
S S rt
^O "o O o
ctf O i * i <
CO O rH CO
OO i-H T-I OS
S o S
W 111 co^oT <M co co"
i-H O CO O O 00 C
tSCO Oi-li-Hi-H Oi-Hi-lOOO
O 43 O
-^* J3 EH *"
i-H i-l i-l i-H i-H O5
< S eo
.C T3 S
_
J gs
to esj
QJ ^^ ^
-O S-, y
$>> <T3 - CO <
' "c ^ ts Si *Z J3
-* O
3 *o *o *o
!d!igli,ll!l!l|l\|!!!|j'
,_j NCOS t-(.S^2 aiw *^i3 "^J * o XWagaCcC
G 'g <u <u <v -
avS a a a >>
|| ^E^Q
_) Q
PL| <J
192
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 193
TABLE 6. Measurements of Calomys callosus expulxus Lund
Head and
Locality body
BRAZIL
Lagda Santa
96
128 s
"
117=
"
108
"
100
"
104
88
"
124
Sao Domingo
Tail
80
76
74
65
67
74
71
85
Hind
foot
19
20
20
20
19.5
18
19.2
21
Ear
Skull,
greatest
length
Zygo- Alveolar
matic length of
breadth molar row
24.5
26.0
28.0
26.7
26
14.3
14.3
13.7
4.0
4.0
4.3
4.0
4.1
1 Cotypes, from Winge (1888, E. Mus. Lundii, 1, no. 3: 17, 20-21).
: Said to be "overstretched."
3 Skull figured by Winge (op. cit., pi. 2, fig. 4).
4 "Type," from Gyldenstolpe (1932, K. Sv. Vet. Akad. Handl., (3), 11: 143).
5 Cotype, from Gyldenstolpe (op. cit.).
6 Approximately.
194
FIELDIANA: ZOOLOGY, VOLUME 46
TABLE 7. Measurements of Eligmodontia typus typus F. Cuvier
Head and
Locality body Tail
ARGENTINA
Hind
foot
Skull,
greatest
Ear length
Zygo- Alveolar
matic length of
breadth molar row
Buenos Aires 1
68
90
20.3
.
" " 2
65
87
19.6
23.5
14.0
3.8
Peru Station 3
75
80
20.4 4
17
23.4
3.6
Bahia Blanca 5
91
95
21.0 4
.
.
Choele-Choel
90
87
25.0
17
26.1
13.3
3.9
" "
90
107
24.0
18
24.9
13.0
4.0
" "
81
108
21.0
18
23.9
12.0
4.0
Chos Malal
88
26.0
17
25.5
13.6
4.2
" "
90
96
24.0
17
25.6
4.2
" "
91
110
25.0
18
25.9
12.9
4.0
Las Lajas
92
102
22.0
17
25.3
4.1
Pilcaniyeu
76
78
21.0
16
24.0
4.1
Huanu Luan
92
87
23.0
24.9
12.3
3.8
Rawson
77
81
25.0
18
23.8
Bas. Canyons 6
85
80
23.0 4
13 7
24.0
12.0
4.0 8
Piedra Clavada
80
72
22.0
15
11.8
3.7
Rio Coyle
12.5
4.1
C. Buen Tiempo
23.8
12.3
3.5
Santa Cruz
70
72
23.0
23.3
11.6
3.7
" "
68
69
23.0
23.0
11.4
3.5
CHILE
L. Sarmiento
83
70
23.0
23.0
12.0
3.9
1 Type of typus Cuvier, from original description (Old French inches converted
to millimeters=l" : 27.07 mm.).
2 Type of typus Cuvier, from Gyldenstolpe (1932, K. Sv. Vet. Akad. Handl.,
2: 142).
3 Type of pamparum Thomas, from original description.
4 Without claw.
5 Type of elegans Waterhouse, from original description.
6 Type of morgani J. A. Allen, from original description.
7 From dry skin.
8 3.5 mm., according to Goodwin (1953, Bull. Amer. Mus. Nat. Hist., 102: 323).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 195
TABLE 8. Measurements of Eligmodoniia ti/pns pneriilus Philippi
Head and
Locality body Tail
Hind
foot
Ear
Skull,
greatest
length
Zygo- Alveolar
malic length of
breadth molar row
BOLIVIA
Challapata'
90
97
25.0 6
20
25.3
13.5
3.8
CHILE
Tarapaca 2
Rfo S. Pedro
93
87
67
88
22.0
23.5 7
22
25.2
13.0
3.7
" " "
78
79
23.5 7
" " "
92
95
24.0 7
25.9
13.8
4.1
" " "
97
93
26.0 7
25.6
13.7
3.9
M
105
88
24. 7
S. Pedro Atacama 3
90
70
21.0 6
ARGENTINA
Abrapampa 4
Chorillos
85
88
80
89
22.0 6
22.0
18
16
25.0
13.2
4.0
"
84
81
23.0
18
Chumbicha*
65
93
20.0
15
21.4
12.0
3.5
Corral Quemado
Chilecito 8
70
80
76
91
22.0 7
23.0"
15
17
22.7
11.7
12.4
4.0
3.6
Media Agua
81
70
89
85
21.0
20.0
15
15
i
1 Type of hirtipes Thomas, from original description.
2 Type of tarapacensis Mann, from original description.
3 Type of puerulus, from original description.
4 Type of jacunda Thomas, from original description.
* Type of marica Thomas, from original description.
6 Without claw.
7 Dry, with claw.
8 Type of moreni Thomas, in spirits, from original description.
196 FIELDIANA: ZOOLOGY, VOLUME 46
Genus Zygodontomys J. A. Allen
Zygodontomys J. A. Allen, 1897, Bull. Amer. Mus. Nat, Hist., 9: 38, pi. 1,
figs. 1-7 (skull, molars).
Type species. Oryzomys cherriei J. A. Allen (= Zygodontomys
brevicauda cherriei J. A. Allen).
Included species. Zygodontomys lasiurus Wagner, brevicauda J. A.
Allen and Chapman.
Distribution
Figure 50
Tropical savannas, brushlands, and forest fringes from Costa
Rica southward into Colombia, western Ecuador, Venezuela, the
Guianas, eastern Brazil and the Mato Grosso, Paraguay and north-
eastern Bolivia; altitudinal range from sea level to approximately
1200 meters above.
Characters
External. Largest member of the Calomys group; form and
appearance Sigmodon-\ike; pelage smoothly adpressed, the cover
hairs slightly hispid; upper parts and sides buff to tawny mixed
with blackish with a resultant agouti pattern; under parts not
sharply defined from sides, gray usually washed with buff; tail
shorter to slightly longer than combined head and body length,
thinly haired, without terminal tuft, brown above, paler beneath
except terminally; hind feet comparatively large, brown or buffy
above, soles relatively well scutulated, plantar surface of heel pilose,
claws strongly developed but length of middle claw measured on
ventral surface not exceeding one-half length of its digit, digital
bristles sparse; fifth hind toe, less claw, not reaching distal end
of first phalanx of fourth toe; ears small, about one-third shorter,
measured from notch, than hind foot with claw; auricular patches
or tufts not present; mammae, 2 2=8.
Cranial (figs. 34, 51, 66). Skull comparatively heavily built,
braincase relatively narrow; zygomata parallel-sided or convergent
anteriorly, widest distance between them less than length from
posterior tips of nasals to anterior border of supraoccipital ; supra-
orbital region broad, the dorsal surface convex in cross section,
width at mid-frontal region more than greatest width of rostrum,
sides divergent, the edges beaded and, sometimes, projected later-
ally as narrow ledges; temporal ridges often present; greatest dis-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 197
FIG. 50.
rturM.<t.
Type localities of the nominal subspecies of Zygodontomyx brerirandti and /..
EXPLANATION OF FIGURE 50
Zygodontomys breeicauda cherriei
Boruca, near Rfo Diquis, Puntarenas, Costa Rica.
Zygodontomys brericauda ventrioxint
Tabernilla, Canal Zone, Panama.
Zygodontomys brericauda xeorsus
San Miguel Island (Isla del Rey), Archipielago dc las Perlas, Golfo do
Panama, Panama.
Zygodontomys brevicauda nanctaemartae
Bonda, Santa Maria, Magdalena, Colombia.
Zygodontomys brevirandn brnnneus
El Saibal, Cundinamarca.
198 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 50 (continued)
Zygodontomys brevicauda stellae
6. Maipures, Vichada, Colombia.
Zygodontomys brevicauda punctulatus
7. Western Ecuador (see text).
Zygodontomys brevicauda thomasi
8. Campo Alegre, Cumana, Sucre, Venezuela.
Zygodontomys lasiurus tobagi [=Z. b. brevicauda?]
9. Tobago, West Indies.
Zygodontomys brevicauda brevicauda
10. Princestown, Trinidad.
Zygodontomys brevicauda microtinus
11. Suriname.
Zygodontomys lasiurus fuscinus
12. Soure, Ilha de Marajo, Para, Brazil.
Zygodontomys lasiurus pixuna
13. Crato, Ceara, Brazil.
Zygodontomys lasiurus lasiurus
14. Lagoa Santa, Rio das Velhas, Minas Gerais, Brazil.
Zygodontomys lasiurus brachyurus
15. Itarare, Sao Paulo, Brazil.
Zygodontomys [?lasiurus] lenguarum
16. Waikthlatingmayaliva, northern Chaco, Paraguay.
Zygodontomys [?lasiurus] tapirapoanus
17. Tapirapoa, Rio Sepotuba, Mato Grosso, Brazil.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 199
tance across fronto-maxillary sutures on dorsal surface subequal
to distance from anterior border of supraoccipital to angle between
fronto-parietal sutures; fronto-parietal sutures crescentic or broadly
angular in outline, never forming a right or acute angle at midline;
interparietal moderately well developed to notably reduced antero-
posteriorly; anterior border of zygomatic plate plane or slightly
concave, the upper corner rounded or pointed; posterior border
of incisive foramina pointed or rounded and sometimes, in old
individuals, not extending behind to anterior plane of first molars;
pitted posterior palatal region usually without median longitudinal
ridge, lateral depressions present or absent, posterior border rounded,
angular, square, or with a blunt median projection; width of meso-
pterygoid fossa at anterior base of pterygoid processes equal to or
greater than width of parapterygoid fossa measured at same plane;
bullae small, their length, less tubes, equal to or less than alveolar
length of molar row; coronoid process well developed and at least
one-half as long as condylar process.
Dental (figs. 44, 49). Upper incisors opisthodont, ungrooved;
molar rows parallel-sided or slightly convergent posteriorly; molars
moderately high-crowned, crested in unworn, secondarily terraced
in worn; individual cusps of upper and lower molars ovate in outline,
those of inner side opposite their analogues of outer side; upper
first molar three or four rooted, the lower two or three rooted;
m 3 from three fourths to equal the length of m 2 ; procingulum of mj
subelliptical or subcordate in outline, an anterior median fold, if
present, never more than a notch in adult, sometimes moderately
developed in Juvenal; m 1 -*- with well-developed anterolabial style
present, the first primary fold becoming an island in moderately
worn tooth; second secondary fold present in unworn, sometimes
in slightly worn, m 1 a ; first minor fold weakly developed and virtually
absent in moderately worn m 3 -'-; a vestigial mesoloph sometimes
present in Juvenal m :i ; procingulum of m 5 ^ rudimentary, absent
in worn teeth; second primary fold reduced to a small shallow
enamel island in moderately worn m, 2 , obsolete in slightly worn
m s ; a paralophule and mesostyle often present, sometimes fused
and bridging paracone and metacone.
Comparisons
Zygodontomys is distinguished from Calomys callosus, its nearest
relative, by larger size throughout, mesopterygoid fossa broader,
dorsal emargination of antorbital foramen shallower, incisive for-
FIG. 51. Zygodontomys brevicauda. Dorsal and palatal aspects of skull and
mandibles to show variation in size (slightly more than
200
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 201
amina wider, cusps more ovate and generally opposed in position,
third lower molar not shorter than second. Other members of the
Calomys group are much smaller and more divergent in external
cranial and dental characters. In the case of skulls only with molars
worn flat, the above cranial and dental characters for distinguishing
Zygodontomys from Calomys callosus serve also to separate the former
from Phyllotis griseoflavus. In addition, first minor fold of adult
m?_ 7 is reduced or obsolete in Zygodontomys as compared with the
same folds in Phyllotis griseoflavus (fig. 44).
Zygodontomys is distinguished from Pseudoryzomys chiefly by
its generally vole-like shape, larger size, relatively shorter tail,
smaller hind foot, broader and distinctly inflated frontal region;
crowns of molars crested, cusps of inner and outer sides very nearly
opposite each other, not arranged in echelon (cf. figs. 44 and 56).
Dark representatives of Zygodontomys closely resemble the reddish
brown Akodon aerosus Thomas (A. dayi Osgood a synonym) and
the Trinidad A. urichi J. A. Allen and Chapman. The skulls are
also similar except that the anterior zygomatic plate is but slightly
produced forward as seen from above, and in A. aerosus supraorbital
ridges or beading is absent. In both species of Akodon the molars are
more hypsodont; the second molars, upper and lower, are markedly
longer than wide; the first and second upper primary folds form
an echelon file with the folds of the opposite side, and after moderate
wear tend to disappear altogether from the crown surface. Other
but not all nominal species of Akodon may be distinguished from
Zygodontomys by one or more of the following characters: proodont
upper incisors; unridged and parallel- or concave-sided interorbital
region; weak anterior zygomatic plate; smaller interparietal; nasals
produced anteriorly to form a trumpet or produced posteriorly well
behind the fronto-maxillary suture; middle claw of forefoot more
than one-half the length of its digit. Each of these characters is less
than generic and some may vary individually and geographically.
No sharp line can be drawn between Zygodontomys and the nominal
species Akodon varius Thomas, A. arviculoides Wagner and A. ob-
scurus Waterhouse.
Zygodontomys has sometimes been confused with Oryzomys (Mel-
anomys) caliginosus. The mesolophodont molar pattern and fine,
but trenchant, differences in cranial structure, especially in the pal-
atal region of the latter, readily separate it from the former.
Oryzomys caliginosus, a vole-like forest dweller, may be replaced by
Zygodontomys where deforestation exposes the one and permits the
introduction of the other.
202 FIELDIANA: ZOOLOGY, VOLUME 46
Remarks
Zygodontomys has been confused with oryzomyine and akodont
rodents. Resemblance to Oryzomys, notably 0. caliginosus, is a case
of parallel development of ecological counterparts, one a grass- and
scrubland vole, the other a forest vole. True Akodon, however,
like Zygodontomys, is a grass- and scrubland vole and resemblance
between the two genera indicates close genetic relationship rather
than convergence. Indeed, Zygodontomys is an annectant form be-
tween phyllotine and akodont rodents. Cranial characters of Zygo-
dontomys combine features of both groups. The high braincase, well-
inflated frontal sinuses, reduced interparietal, posteriorly narrowed
incisive foramina and shorter than usual palate in many specimens of
Zygodontomys, are definitely akodont characters. The molar pattern
of Zygodontomys is less modified than that of Akodon proper but repre-
sents a stage in the line leading to the highly selenodont molars of the
Central American akodont genus Scotinomys. Further clarification of
the status of Zygodontomys requires a reassessment of the systematics
of akodont rodents comparable to the present one of phyllotines.
The following account and arrangement of the species and sub-
species of Zygodontomys are typologically based.
The Species
Twenty named forms of Zygodontomys are taken into account
here. Types of sixteen of these were examined by me and found
to be conspecific. Of the four types not seen, the first, Zygodontomys
lasiurus Lund, is known to me by a paratype in the British Museum
(Natural History) and the original description and figures. The
second, pixuna Moojen, from Ceara, Brazil, was originally distin-
guished from topotypes of Zygodontomys lasiurus by paler color
and more slender skull. Material from Ceara and Piauhy in the
collection of Chicago Natural History Museum shows that specific
status first accorded pixuna is untenable, and subspecific separation
from lasiurus is doubtful. The third named form, brachyurus, is
here identified as a Zygodontomys solely on evidence from the liter-
ature. There is nothing to indicate specific distinction from Z.
lasiurus. The fourth named form, Zygodontomys seorsus Bangs,
from San Miguel Island, Panama, is represented here by six para-
types. They average larger than populations of Zygodontomys brevi-
cauda from Trinidad, Panama and northern Colombia, but other-
wise are practically indistinguishable.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 203
Oryzomys obtusirostris J. A. Allen, 1900, subsequently referred
by its author to Zygodontomys, is a true Oryzomys.
Specimens of Zygodontomys at hand segregate into two geographic
groups. Each of these is provisionally accorded specific rank. The
first or northern group, typified by Z. brevicauda, ranges from north
of the Rio Amazonas into Central America. It is characterized by
widely opened, ovate incisive foramina, longer palate, prominently
pitted posterolateral palatal depressions, posterior border of palate
with either a rounded or lancet-shaped excision, mesopterygoid fossa
extremely wide, interparietal well developed antero-posteriorly, cap-
sular projection of mandible usually located at base of coronoid
process, upper incisors opisthodont. The type species of the south-
ern group, Zygodontomys lasiurus, occupies suitable habitats in Bra-
zil south of the Amazonas. It is distinguished by incisive foramina
usually narrower posteriorly than anteriorly, palate shorter, the
posterior border commonly with a short blunt median process,
posterolateral palatal pits generally situated posteriad to hind border
of palate, mesopterygoid fossa narrower relative to intermolar width
of palate, interparietal reduced antero-posteriorly, capsular projec-
tion of mandible usually located posteriad to base of coronoid proc-
cess, upper incisors opisthodont to practically orthodont. Many
juvenals and subadults of the northern group are intermediate and,
sometimes, more nearly like adults of the southern group.
Recognition of the subspecies listed below is uncritical.
Measurements of the types of each of the named forms of Zy-
godontomys are given in Table 9.
Since the present review was written and submitted for publica-
tion (prior to 1957), Cabrera's (1961, p. 462) classification of
Zygodontomys has come to hand (March, 1962). This authority
recognizes four species. His Z. lasiurus agrees with mine but his
microtinus, punctulatus and brevicauda are treated below as sub-
species of the last-named form.
NORTHERN GROUP
Zygodontomys brevicauda cherriei J. A. Allen
Oryzomys cherriei J. A. Allen, 1895, Bull. Amer. Mus. Nat. Hist., 7: 329.
Type locality. Boruca, near Rio Diquis, Puntarenas, Costa Rica.
Remarks. Three paratypes, received in exchange, are in the
collection of Chicago Natural History Musuem.
204 FIELDIANA: ZOOLOGY, VOLUME 46
Zygodontomys brevicauda ventriosus Goldman
Zygodontomys cherriei ventriosus Goldman, 1912, Smithsonian Misc. Coll., 56,
No. 36: 8.
Type locality. Tabernilla, Canal Zone, Panama.
Remarks. Two paratypes, received in exchange, are in the col-
lection of Chicago Natural History Museum.
Zygodontomys brevicauda seorsus Bangs
Zygodontomys seorsus Bangs, 1901, American Nat., 35: 642.
Type locality. San Miguel Island [Isla del Rey], Archipielago
de las Perlas, Golfo de Panama, Panama.
Remarks. Six paratypes, received in exchange, are in the col-
lection of Chicago Natural History Museum.
Zygodontomys brevicauda sanctaemartae J. A. Allen
Oryzomys sanctaemartae J. A. Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12: 207.
Type locality. Bonda, Santa Marta region, Magdalena, Colombia.
Remarks. Doubtfully separable from brunneus Thomas. See re-
marks under Z. b. brunneus.
Zygodontomys brevicauda brunneus Thomas
Zygodontomys brunneus Thomas, 1898, Ann. Mag. Nat. Hist., (7), 2: 269.
Zygodontomys griseus J. A. Allen, 1913, Bull. Amer. Mus. Nat. Hist., 32: 599
type locality, El Triumfo, Magdalena Valley, Colombia, 600 ft. above
sea level [about latitude of La Dorada].
Zygodontomys fraterculus J. A. Allen, 1913, Bull. Amer. Mus. Nat. Hist., 32:
599 type locality, Chicoral, Rfo Coello, Magdalena Valley, Tolima,
Colombia, altitude, 1800 ft. above sea level.
Type locality. El Saibal, Magdalena Valley, Cundinamarca,
Colombia.
Remarks. The Zygodontomys collected by the writer in Colombia
represent all forms, except stellae, described from that country.
This material and field observations will form the basis for a more
detailed account of the genus.
Zygodontomys brevicauda punctulatus Thomas
[tlHesperomys renggeri, Tomes (nee Waterhouse), 1860, Proc. Zool. Soc. Lon-
don, 1860: 213 Ecuador (without precise locality).
Hesperomys arvicoloides, Tomes (nee Pictet), 1860, Proc. Zool. Soc. London,
1860: 262 Ecuador (without precise locality).
Acodon [sic] punctulatus Thomas, 1894, Ann. Mag. Nat. Hist., (6), 14: 361.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 205
Type locality. "Ecuador (probably Pallatanga)," but if Ecuador
is the country of origin it is much more likely that the type was
taken in the lowlands of western Ecuador as indicated on the map
(fig. 50).
Remarks. To date, punctulatus is known only from the type.
Zygodontomys brevicauda stellae Thomas
Zygodontomys stellae Thomas, 1899, Ann. Mag. Nat. Hist., (7), 4: 380.
Type locality. Maipures, upper Rio Orinoco, Vichada, Colombia.
Zygodontomys brevicauda thomasi J. A. Allen
Zygodonlomys thomasi J. A. Allen, 1901, Bull. Amer. Mus. Nat. Hist., 14: 39.
Type locality. Campo Alegre, Cumana, Sucre, Venezuela.
Remarks. Doubtfully distinct from brevicauda.
Zygodontomys brevicauda brevicauda J. A. Allen and Chapman
Oryzomys brevicauda J. A. Allen and Chapman, 1893, Bull. Amer. Mus. Nat.
Hist., 5: 215.
Akodon frustralor, J. A. Allen and Chapman, 1897, Bull. Amer. Mus. Nat.
Hist., 9: 20 type locality, Caura, Trinidad.
Zygodontomys brevicauda tobagi 1 Thomas, 1900, Ann. Mag. Nat. Hist., (7), 5:
274 type locality, Island of Tobago, British West Indies.
Type locality. Princestown, Trinidad.
Remarks. Three paratypes of brevicauda and one of fntstrator,
received in exchange, are in the collection of Chicago Natural
History Museum.
Zygodontomys brevicauda microtinus Thomas
Oryzomys microtinus Thomas, 1894, Ann. Mag. Nat. Hist., (6), 14: 358.
Type locality. Suriname.
SOUTHERN GROUP
Zygodontomys lasiurus fuscinus Thomas
Akodon fusdnus Thomas, 1897, Ann. Mag. Nat. Hist., (6), 19: 496.
Type locality. Soure, Ilha de Marajo, mouth of Amazon, Pard,
Brazil.
1 Goodwin (1962, Amer. Mus. Nat. Hist., Novit., no. 2096, p. 7) re-cognizes
Zygodontomys brevicauda tobago [sic] as a distinct race larger than Trinidad breri-
caitda.
206 FIELDIANA: ZOOLOGY, VOLUME 46
Zygodontomys lasiurus pixuna Moojen
Zygodontomys pixuna Moojen, 1943, Bol. Mus. Nac., Rio de Janeiro, Zool.,
no. 5: 8, fig. 2 (skull and molars).
Type locality. Crato, Ceara, Brazil.
Zygodontomys lasiurus lasiurus Lund
Mus lasiurus Lund, 1839, Ann. Sci. Nat., Paris, 11: 233 (nomen nudum).
Lund, 1840, Mag. Nat. Hist., new ser., 4: 55 (description inadequate).
Lund, 1841, K. Danske Vidensk. Selsk. Afhandl., 8: 50-52, 134, 266,
280, 294.
Habrothrix lasiurus, Winge, 1888, E Mus. Lundii, 1, pt. 3: 31, pi. 1, fig. 8
(head), fig. 9, (hind foot), pi. 2, fig. 11 (skull), fig. lla (molar).
[Zygodontomys] lasiurus, Thomas, 1902, Ann. Mag. Nat. Hist., (7), 9: 61.
Type locality. Lagoa Santa, Rio das Velhas, Minas Gerais, Brazil.
Remarks. Ellerman (1941, pp. 417, 418) regards lasiurus as
"probably a member of the genus Akodon." More probable, in my
opinion, is that a number of species in the British Museum referred
by Thomas to Akodon should have been determined as Zygodontomys
lasiurus. One of the types in the Copenhagen Museum is described
and figured by Winge (supra cit.). Another specimen of the original
type series, collected by Reinhardt in Lagoa Santa, is in the British
Museum (BM No. 88.1.9.4).
Zygodontomys lasiurus brachyurus Wagner
Hesperomys brachyurus Wagner, 1845, Arch. Naturg., 11: 147. Wagner, 1848,
Abh. K. Akad. Miinchen, 5: 313. Pelzeln, 1883, K. K. Zool.-Bot. Ge-
sellsch., Beih., 33: 70.
Akodon sp. Thomas, 1901, Ann. Mag. Nat. Hist., (7), 8: 530 Rio Jordao,
Minas Gerais, Brazil.
[Zygodontomys} brachyurus, Thomas, 1902, Ann. Mag. Nat. Hist., (7), 9: 61
(closely allied to Mus lasiurus).
Zygodontomys lasiurus, Vieira, 1955, Arq. Zool., Sao Paulo, 8: 146 Ipiranga
and Piracicaba, Sao Paulo, Brazil.
Type locality. Itarare 1 , Sao Paulo, Brazil.
Zygodontomys [? lasiurus] lenguarum Thomas
Akodon lenguarum Thomas, 1898, Ann. Mag. Nat. Hist., (7), 2: 271.
Type locality. Waikthlatingmayaliva, northern Chaco, Paraguay.
Remarks. The dividing line between this, the following (tapir-
apoanus), and Akodon obscurus Waterhouse from Uruguay, is not
clear.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 207
Zygodontomys [? lasiurus] tapirapoanus J. A. Allen
Zygodontomys tapirapoanus J. A. Allen, 1916, Bull. Amer. Mus. Nat. Hist.,
35: 528.
Type locality. Tapirapoa, Rio Sepotuba, Mato Grosso, Brazil.
Remarks. Specimens of Zygodontomys from Buena Vista, Santa
Cruz, Bolivia, in the British Museum (Natural History), are referable
to tapirapoanus.
TABLE 9. Measurements of nominal subspecies of Zygodontomys lasiurus Lund
and Zygodontomys brericanda J. A. Allen and Chapman
(Measurements are of the type specimens unless otherwise indicated.)
Skull,
Zygo-
Alveolar
Head and
Hind
greatest
matic
length of
Name
Sex
body
Tail
foot
Ear
length
breadth
molar row
brachyitrns
<?
133
63
24 8
13
brevicauda
J
32.5
17.3
4.5'
bmnneus
9
152
117c
25 2 , 8
19 2
34.0 3
17.7 3
5.0 3
cherriei
<?
30.0
16.0
4.6
fratercvlus
9
115
83
26*
28.0
13.5
4.0'
frustrator
168
65
26
10 2
26.0
13.0
4.5
fuscinus
cf
98 4
64 4
19 4 , 8
13*
14.9
4.5
griseus
tf
133
101
26
28.5
14.0
4.2
lenguarum
115
76
21"
14
28.5
16.0
4.7 s
lasiurus
121
74
21"
27.0 s
4.8 s
microlinus
9
115<
84 4
24. 5V
16<
29.7
16.0
4.1
pixuna
9
86
120"
24.0
28.4
15.0
4.6
punctnla(Hx
132
71
22.0 2 , 8
14 2
29.6
15.0
4.2
sanctaemartae
9
129
100
27.0
15 2
34.0
17.7
5.0
seoraus
c?
180
140
34.0
18
32.8
18.4
5.2
xtellae
<?
110
38'
20.6*
17.7
30.0
15.0
4.2
tapirapoanus
9
130
80
25
29.5
15.8
5.0
thomasi
9
125
99
23
18
16.0
4.0
tobagi
o"
146
100
30"
18
35.0
19.0
4.6
rentriosux
<?
136
104
28
31.7
16.4
4.6
1 Crown length; measuring points of molar row in others unknown.
On dry skin.
3 Of cotype.
4 Of type in spirits.
s Of cotype, from Gyldenstolpe (1932, K. Sv. Vet. Akad. Handl., 2: 147).
6 Head and body and tail measurements apparently reversed; Moojen gives
head and body 112.5 and tail 80.5 as average for 10 adult female cotypes.
7 Bob.
8 Without claw.
PHYLLOTIS SECTION
The characters of the section are given in the key (p. 118). For
the geographic range, see maps (figs. 1 and 52).
Genus Pseudoryzomys Hershkovitz
Pseudoryzomys Hershkovitz, 1959, Proc. Biol. Soc. Washington, 72: 8.
Type species. Oryzomys wavrini Thomas, by original designation.
Included species. Pseudoryzomys wavrini Thomas.
Distribution
Figure 52
Known only from the Chaco of Paraguay and Argentina.
Characters
External. Form and appearance as in palustrine and semi-
aquatic cricetines; pelage long, comparatively coarse, and loose but
not lax; upper parts from snout to base of tail dark brown mixed
with buffy, the dark basal portion of the hairs showing through;
tail subequal to combined head and body length; thinly haired,
without terminal tuft, brown above, paler beneath; hind foot com-
paratively large, average length, with claw, more than 22 per cent
of combined head and body length; soles, including plantar surface
of heel, well scutulated and entirely bare; webbing between middle
digits of hind foot comparatively well developed, membrane between
digits 3 and 4 extending to distal ends of first phalanges (fig. 53);
claws weak, digital tufts thin; first hind toe, less claw, not extending
to base of second; fifth hind toe, less claw, not reaching distal end
of first phalanx of fourth toe; ears small, about one third shorter,
measured from notch, than hind foot with claw; fifth (outer posterior)
postdigital plantar pad obsolete or absent.
Cranial (figs. 54,a, 55,a). Skull elongated, especially in frontal
region, zygomatic arches parallel-sided, widest distance between them
subequal to, or less than length from posterior tips of nasal to anterior
208
PHYLLOTIS
ANDINOMYS
CHINCHILLULA
GALENOMYS
PSEUDORYZOMYS
FIG. 52. Distribution of the genera of the Phyllolis section.
209
210
FIELDIANA: ZOOLOGY, VOLUME 46
border of interparietal (not supraoccipital, the point used for measur-
ing in all other phyllotines) ; supraorbital region narrow mid-frontally,
the dorsal surface flat or concave in cross section, width at mid-
Pseudoryzomys
wavrini
Oryzomys
palustris
FIG. 53. Plantar surface of right
hind foot of Pseudoryzomys wavrini
and Oryzomys palustris.
frontal plane less than greatest width of rostrum, sides divergent,
the edges beaded and continuing on parietals as temporal ridges;
greatest distance across fronto-maxillary sutures on dorsal surface
subequal to distance from anterior border of interparietal to angle
between fron to-parietal sutures; fronto-parietal sutures crescentic,
not forming a right or acute angle at midline; interparietal well devel-
oped ; anterior border of zygomatic plate deeply concave, the upper
corner pointed; incisive foramina narrow, their posterior borders ex-
tending behind anterior plane of first molars; palate hardly as wide
between first molars as greatest length of m 1 ; paired anterior palatal
pits situated across maxillo-palatal suture on middle of palatal bridge;
posterior palatal region with a low median ridge, lateral depressions
present; width of mesopterygoid fossa at base of hamular processes
equal to or greater than width of parapterygoid fossa measured at
same plane; length of bulla, less tube, subequal to alveolar length of
molar row; coronoid process well developed, at least one-half as long
as condylar process.
Dental (fig. 56,a). Upper incisors opisthodont, ungrooved; molar
rows parallel-sided; first upper and lower molars four-rooted; m^ as
long as, or longer than, m^; molars moderately high crowned, terraced
in unworn condition and tending to lamination in the upper, triangu-
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS '211
lation in the lower; individual cusps arranged nearly in echelon,
compressed antero-posteriorly, the upper elliptical in outline, the
lower subtriangular; procingulum of m 1 elliptical in outline and dis-
tinctly biconulate in unworn condition, of m r subtriangular, without
anterior fold; mesolophs weakly developed or absent, mesolophid
absent; a poorly developed mesostyle(-id) may be present in m 1 ;
first primary fold, with corresponding anterolophs, of m 3 -"- well de-
veloped in unworn teeth; second secondary folds present as small
enamel islands in unworn m- 1 -"^; first internal folds of m 3 -' 3 - not dis-
crete but recognizable; first minor fold weakly developed in unworn
to moderately worn m% obsolete in m-; procingulum of m z 3 weakly
developed ; second primary fold well developed in moderately worn
m T _ 7 ; first minor fold present in m?-?.
Comparisons
The combination of characters that distinguish Pseudoryzomys
as a genus from all other phyllotines includes moderate size, small
ears, large hind feet, soles entirely naked and with five plantar tuber-
cles, webbing between toes well developed, unspecialized tail subequal
to combined head and body length, zygomatic spread extremely nar-
row relative to skull length, interorbital region narrow with divergent
and beaded supraorbital edges.
Pseudoryzomys is treated as a member of the Phyllotis section
because of its terraced molars. In most other respects it appears
to be more nearly related to members of the Calomys section. Crani-
ally, it combines the narrow interorbital region characteristic of most
phyllotines and the divergent and beaded supraorbital edges of Zygo-
dontomys, Calomys callosus and Phyllotis griseoflams. This combi-
nation occurs in no other phyllotine but is nearly approached in
Phyllotis darwini wolffsohni.
Pseudoryzomys most nearly resembles Zygodontomys and Calomys
callosus in size, pilosity of tail, and texture and color of pelage. The
hind foot of Zygodontomys, however, is not specially adapted for
natation, is smaller, more hairy, provided with stronger claws but
with weaker interdigital webbing. Furthermore, Zygodontomys is
larger, with tail relatively shorter, pelage finer, thicker, shorter,
color of upper surface and sides of head and body more uniform
and evenly ticked. Calomys callosus is approximately the same bulk
as Pseudoryzomys but its tail is shorter, feet smaller, hirsute, com-
paratively delicate in structure, and without interdigital webbing.
212
FIELDIANA: ZOOLOGY, VOLUME 46
FIG. 54. Dorsal and palatal aspects of skulls of a, Pseudoryzomys wavrini
(with nasal tips missing) ; 6, Calomys callosus; c, Oryzomys palustris. (About X 1 Y<i).
Texture and color of pelage in both Zygodontomys and Calomys are
more nearly as in Oryzomys than Pseudoryzomys. In neither Zygo-
dontomys nor Calomys is the antorbital foramen as deeply excised
or the anterior border of the zygomatic plate as deeply concave.
Resemblances between Pseudoryzomys and palustrine species of
Oryzomys (figs. 53-55) are of a convergent nature. The hind feet of
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 213
FIG. 55. Side view of skull and mandible of a, Psendoryzomys wavrini (with
nasal tips missing); 6, Oryzomys palustris. (About X IJ^-)
Pseudoryzomys, larger and more powerfully developed than in any
other phyllotine, are like those of Oryzomys palustris. The wholly
bare soles and well-developed interdigital webbing are also char-
acters of Oryzomys and particularly of the oryzomyine Nectomys,
rather than of phyllotines. These external characters, nevertheless,
occur in nearly every murid more or less adapted for aquatic life.
The long palate with posterolateral pits common to phyllotines and
oryzomyines is narrower in Pseudoryzomys than in any oryzomyine.
The hypsodont molars, advanced stages of lamination and triangu-
lation of the crowns and cusps respectively, and the absence of the
mesoloph(-id) are other important dental characters distinguishing
Pseudoryzomys from all oryzomyines.
Remarks
Pseudoryzomys is the semi-aquatic representative of the phyllo-
tine rodents. Its adaptations for a palustrine and aquatic habitat
compare with those of Oryzomys palustris. They fall short of those
already attained by Nectomys among oryzomyines and Holochilus
FIG. 56. Upper and lower molars of a, Pseudoryzomys wavrini; b, Calomys
callosus; c, Oryzomys palustris.
214
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 215
among sigmodonts. The phyllotine Zygodontomys is less modified
for a palustrine habitat than Pseudoryzomys, and its direction of
evolution is toward the vole-like rather than the natatorial type.
TABLE 10. Measurements of Pseudoryzomys uwrini Thomas
Head and
Locality body
Tail
Hind
foot
Ear
Skull,
greatest
length
Zygo-
matic
breadth
Alveolar
length of
molar row
PARAGUAY
Jesematathla 1
106
106
25
16
28.8
15.5
4.8
Mision
120
120
26
17
30.3
16.2
5.0
ARGENTINA
Tacaagle
105 2
110*
29*
122
3
14.0
4.8
1 Type.
J External measurements from dry skin.
s Condylo-incisive length 25.3 (in type, 26.6).
Pseudoryzomys wavrini Thomas
Oryzomys wavrini Thomas, 1921, Ann. Mag. Nat. Hist., (9), 7: 177. Eller-
man, 1941, The families and genera of living rodents, 2: 341, 354.
Pseudoryzomys wavrini Hershkovitz, 1959, Proc. Biol. Soc. Washington, 72:
9 PARAGUAY: Chaco Boreal (Jesematathla; Mision); ARGENTINA:
Formosa (Tacaagle, Rfo Porteno).
Type. "Young adult male" skin and skull, British Museum
(Natural History) no. 20.12.18.16; collected 15 August, 1920, by
the Marquis de Wavrin.
Type locality. Jesematathla, west of Conception, Chaco Boreal,
Paraguay; altitude, 100 meters above sea level.
Distribution (fig. 52). Chaco Boreal of Paraguay and Chaco
Central, Formosa in Argentina.
Characters. Those of the genus.
Remarks. In describing wavrini as an Oryzomys Thomas was mis-
guided by a certain amount of convergence in a few superficial char-
acters. The diagnostic cranial characters and similarities with such
truly related forms as the sympatric Calomys callosus were over-
looked, and the absence of the mesoloph(-id), the "cross-crochet"
of Thomas, was brushed aside as a "mere abnormality." Ellerman
(supra cit.) regarded wavrini as aberrant within the framework of
the genus Oryzomys. He did note (p. 341), however, its resemblances
to Hesperomys (= Calomys).
Nothing is known of the habits of Pseudoryzomys wavrini. The
morphology indicates that Pseudoryzomys fills nearly the same eco-
216 FIELDIANA: ZOOLOGY, VOLUME 46
logical niche among phyllotines as Nectomys does among oryzomyines
and Holochilus among sigmodonts.
The characterization of Pseudoryzomys is based primarily on a
subadult male at hand from Mision Tacaagle, Rio Porteno, Chaco
Central, Argentina, collected 27 November, 1925, by Hans Krieg.
The type of Oryzomys wavrini, with which comparison was made,
is fully adult and in thick winter (August) pelage.
Measurements. See Table 10 (p. 215).
Specimens Examined. Total 3. PARAGUAY. Chaco Boreal:
Jesematathla, 1, the type (BM); Mision, 1 (BM). ARGENTINA
Formosa: Tacaagle, Rio Porteno, 1 (CNHM).
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 217
Genus Phyllotis Waterhouse
Phyllolis Waterhouse, 1837, Proc. Zool. Soc. London, 1837: 28 subgenus of
Mus; included species, darwini, jcanthopygus, griseoflavus, Thomas, 1884,
Proc. Zool. Soc. London, 1884: 449 subgenus of Hesperomys; Mut* dar-
irini Waterhouse, type by selection. Thomas, 1896, Proc. Zool. Soc. Lon-
don, 1896: 1020 full genus. Thomas, 1897, Ann. Mag. Nat. Hist., (6),
20: 550 in text; generic rank. Thomas, 1916, op. cit., (8), 17: 141
diagnosis. Osgood, 1947, Jour. Mammal., 28: 165. Pearson, 1958, Univ.
California Publ. Zool., 56: 391 revision.
Auliscomys Osgood, 1915, Field Mus. Nat. Hist., Zool. Ser., 10: 190 sub-
genus of Phyllotis; Reithrodon pictus Thomas, type. Thomas, 1926, Ann.
Mag. Nat. Hist., (9), 17: 317 genus. Osgood, 1943, Field Mus. Nat.
Hist., Zool. Ser., 30: 210 subgenus of Phyllotis.
Graomys Thomas, 1916, Ann. Mag. Nat. Hist., (8), 17: 141 genus; type,
Mus griseoflavus Waterhouse. Osgood, 1916, Field Mus. Nat. Hist., Zool.
Ser., 10: 207 subgenus of Phyllotis. Thomas, 1919, Ann. Mag. Nat.
Hist., (9), 3: 495 genus. Osgood, 1947, Journ. Mammal., 28: 170
subgenus of Phyllotis.
Paralomys Thomas. 1926, Ann. Mag. Nat, Hist., (9), 17: 315 Phyllotis gerbil-
lus Thomas, type. Osgood, 1947, Journ. Mammal., 28: 171 subgenus of
Phyllotis.
Loxodonlomys Osgood, 1947, Journ. Mammal., 28: 172 subgenus of Phyllotis;
type, Mus micropus Waterhouse.
Hesperomys, Thomas (not Waterhouse), 1884, Proc. Zool. Soc. London, 1884:
449 part, Phyllotis subgenus, only. Ellerman, 1941, The families and
genera of living rodents, London, 2: 446, 448 part, Paralomys, sub-
genus only.
Eligmodontia, Thomas (not Cuvier), 1893, Proc. Zool. Soc. London, 1898: 210
part, Phyllotis griseoflavus only. Thomas, 1902, Ann. Mag. Nat. Hist.,
(7), 9: 132 and footnote domorum, cachinus only.
Euneomys, Thomas (not Coues), 1901, Ann. Mag. Nat. Hist., (7), 8: 254
part, species pictus and sublimis only. Thomas, 1916, Ann. Mag. Nat.
Hist., (8), 17: 143 part, Auliscomys subgenus, only.
Type species. Mus darwini Waterhouse (= Phyllotis darwini
Waterhouse) by subsequent designation (Thomas, 1884, p. 449).
Included species. Phyllotis darwini, osilae, andium, haggardi,
micropus, gerbillus, boliviensis, sublimis, pictus, griseoflavus, edithae,
amicus, hypogaeus.
Distribution
(Figures 52, 57)
From the Ecuadorian Andes at the equator south along the Andes
and coast of Peru and Chile to the Straits of Magellan, west over the
J.*.0.*." griseo'lavu
hypogaeus
edilhae
FIG. 57. Distribution of the species of Phyllotis.
218
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 219
Bolivian Andes into the Paraguayan Chaco, and continuing south-
ward through the Andes, Sierras Pampeanas, Chaco and Patagonian
regions of Argentina; altitudinal range from sea level to over 5,500
meters above, or to limits of perpetual snow. The species of the
Phyllotis darwini complex (darwini, osilae, (indium, haggardi) range
over most of the area occupied by the genus from tropical zone to
temperate zone, in deserts and on humid mountain sides. In con-
trast, Phyllotis gerbillus is restricted to a few hundred square miles of
desert about Piura in northwestern Peru. P. micropus is known only
from the cold, humid cordilleras that form the boundary between
southern Chile and Patagonia. The treeless, sandy and rocky
highlands above 3400 meters in Peru, Bolivia, northern Chile,
and northern Argentina are inhabited by P. sublimis. The range of P.
boliviensis is the same, except that it does not extend into Argentina.
P. pictus is a third highland form not known from Argentina and
Chile, but its range extends farthest north in Peru. Phyllotis griseo-
flavus prefers the scrublands from sea level to nearly 3000 meters
above, in Argentina, Paraguay and Bolivia. A similar species, P.
amicus, occupies the semiarid scrublands of western Peru. Two
species, edithae and hypogaeus, from Argentina, are of uncertain
status and known only from the types. Both occur within the range
of Phyllotis griseoflavus griseoflavus and it has been suggested (cf.
p. 455) that they are identical with it.
Characters
External. External form adapted for terrestrial and scansorial
life; size variable, pelage long, fine; body elongate, tail shorter to
longer than combined head and body length; ears large, length from
notch shorter to longer than hindfoot length; postauricular patches
sometimes present, rarely conspicuous; fifth hind toe (fig. 3), less
claw, reaching distal end of first phalanx of fourth toe, the first hind
toe at least to base of first phalanx of second toe. Underside of heel
hairy, remainder of sole naked or, sometimes, with a sparse covering
of short bristles; plantar pads naked, six in number, the middle three
usually enlarged but not coalesced; mammae eight.
Cranial (figs. 58-60). Dorsal contour of skull flat or slightly
convex; supraorbital region broad or narrow with sides parallel, con-
cave or divergent; fron to-parietal sutures crescentic in outline, not
forming a right or oblique angle at midline, combined width on dor-
sal surface usually more than greatest width across fron to-maxillary
sutures and more than alveolar length of molar row; interparietal
220 FIELDIANA: ZOOLOGY, VOLUME 46
well developed; palate broad, greatest width between inner borders
of first molars more than length of m-; pitted posterolateral portion
of palate little to moderately excavated; width of mesopterygoid
fossa, measured at anterior base of pterygoid processes, approxi-
mately equal to greatest width of m-, always more than width of
m-, but less than width of parapterygoid fossa measured at same
plane; parapterygoid fossa shallow or moderately excavated.
Dental (figs. 59, 67-69). Upper incisors variable in position, their
anterior face grooved or smooth. Molar crowns low or moderately
high ; occlusal surface of unworn or moderately worn molar plane or
terraced, outline of individual cusps, as seen on occlusal surface,
usually subovate but often tending to triangulation or lamination;
upper first molars with 4, sometimes 3 roots, lower with 3 or 4 roots;
procingulum of first upper molar ovate, triangular or subcordate in
outline, never completely divided into two conules; anteroloph of
m^ reduced or well developed, of m- reduced or absent; postcingulum
of all upper molars obsolete or absent; first minor folds of m-' 3 - obso-
lete or absent; a vestigial mesoloph sometimes present; discrete in-
ternal folds absent; procingulum of m T usually undivided; procingu-
lum obsolete in m^_^; postcingulum of m T present and normally well
developed, of m^ present but may be obsolete in worn tooth, of m 7
vestigial or absent; minor fold present at least in slightly worn m^,
obsolete or absent in m^.
Comparisons
The genus Phyllotis is distinguished from genera of the Calomys
section (Calomys, Eligmodontia, Zygodontomys} by molars terraced
or planed, not crested (figs. 14, 49), procingulum of m^- uniconulate,
mesostyle absent or extremely reduced; from Calomys and Zygodon-
tomys by the long outer toes of hind foot; from Zygodontomys by
finer pelage, narrower mesopterygoid fossa and more broadly ex-
panded parapterygoid fossa; from Eligmodontia by generally larger
size and absence of hairy cushion on sole of hind foot. Compared
with other genera of the phyllotine section (figs. 3, 61-63, 69)
the typical genus is distinguished from Galenomys primarily by the
practically naked distal half of sole, flat or slightly convex dorsal
contour of skull, and by greater width of mesopterygoid fossa rela-
tive to width of third upper molar; from Chinchillula and Andinomys
by smaller size, broader palate relative to length of first upper molar,
less hypsodont molars, and less triangulate cusps; from Chinchillula
by absence of well-defined contrasting color pattern on upper parts;
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 221
from Andinomys by ordinary orientation of the upper incisors at
median line; from Pseudoryzomys by smaller feet, longer outer digits,
hairy heel and generally broader skull.
Similarities between South African Mystromys and New World
Phyllotis noted by Ellerman (1941, pp. 444, 445) are common to
many cricetines while differences in certain details of cranial and
dental structure definitely separate Mystromys from all other genera.
A skull of Mystromys (figs. 60, 64-66) compared with skulls of phyl-
lotines reveals the following distinctive characters: Coronoid and
condylar processes of mandible long, slender and subequal in length;
exposed portion of lower incisor about one and one-half times length
of lower molar row; parapterygoid fossa deep (but approximately
equal in Chinchillula); external auditory meatus directed ventrally
as well as laterally; sphenopalatine vacuities large but lateral wings
of presphenoid fully ossified (thinly ossified and largely fenestrated
in phyllotines); incisive foramina extremely narrow, parallel-sided
and longer than in phyllotines; preorbital foramen sac-like, the lat-
eral wall inflated (compressed, with slit-like opening in phyllotines);
premaxillary extending anteriad to nasal and both elements lying
posteriad to antero-vertical plane of incisors; interorbital region rela-
tively narrower than in phyllotines; interparietal narrow antero-
posteriorly, subtrapezoidal in outline with long base posteriad;
median longitudinal occipital crest well developed and backward
sloping (weakly defined or absent in phyllotines) ; molars (figs. 66, 67)
crested (most nearly as in Zygodontomys) , pattern greatly simplified,
with pro- and post-cingula reduced, and without mesoloph(-id) or
mesostyle(-id) ; third molar less than one-half size of second and with
second primary fold rotated posteriorward (also see pp. 24, 107 for
additional remarks on Mystromys).
Variation
The largest species, Phyllotis griseoflavus, is a fourth smaller than
full-grown house rats of the genus Rattus. The smallest species,
P. gerbillus, is the size of the house mouse, Mus musculus. The tail
varies from nearly half again as long as head and body length in
the scansorial P. griseoflavus, to as little as a third as long in the
vole-like subliwis. In pilosity and color, the tail varies almost as
much intraspecifically as intragenerically. The high Andean P.
sublimis has moderate-sized ears, but it lives side by side with ex-
tremely large-eared P. boliviensis. Even greater contrast in size
exists between the smallest-eared P. gerbillus of the desert coast of
222 FIELDIANA: ZOOLOGY, VOLUME 46
northern Peru and its geographic neighbor, P. amicus, with very
large ears. The desert dwelling P. gerbillus is also the palest spe-
cies, while the darkest, P. micropus, inhabits the cold, humid Pata-
gonian Andes. The same correlation between color of animal and
humidity of habitat obtains throughout the range of the genus.
The small, delicately formed skull of P. gerbillus differs grossly
from the large, angular one of boliviensis. Nevertheless, there is com-
plete intergradation in cranial characters between all species of the
genus (figs. 58, 59). A narrow parallel-sided or constricted interorbital
region characterizes the P. darwini group, micropus, boliviensis, sub-
limis and pictus. The broad, divergent-sided type of interorbital region
is found in gerbillus, amicus and griseoflavus, where it is extreme.
However, some individuals of the P. darwini group, notably P. dar-
wini wolffsohni and P. amicus, approach each other so nearly in the
shape of the interorbital region that distinction between the two
types is not always obvious. The zygomata are little expanded,
practically parallel-sided in darwini, gerbillus, griseoflavus, become
well-bowed in boliviensis, sublimis and pictus, and generally triangu-
lar-shaped in P. micropus. The interparietal is well developed in the
genus, but rather small in P. sublimis. Bullae are neither markedly
small nor exceptionally large in any species. They are most inflated
in P. boliviensis, somewhat less in griseoflavus, and least in the P.
darwini complex and P. sublimis.
Dental characters are fully intergrading among the species of
Phyllotis (figs. 59, 67, 68). All molar crown modifications are based
on the simplified or tetralophodont pattern, but the mesoloph ap-
pears occasionally in all species as a slight projection or, usually, as
a mere sinuosity of the connecting enamel ridge between protocone
and hypocone. The incisors vary in angle of projection, from opistho-
dont in most species to generally orthodont in pictus and chiefly pro-
odont in boliviensis. Grooves of the anterior surface of the incisors
are always present, though weakly etched, in P. pictus, less constantly
present and faintly indicated in sublimis, and obsolete in boliviensis.
Molar rows vary from parallel-sided in most species to convergent
posteriorly in haggardi and amicus, divergent posteriorly in micropus,
and bowed in some individuals of boliviensis. Molar crowns are lowest
in gerbillus, highest in the darwini complex, micropus and boliviensis.
The crowns are terraced in gerbillus and pictus, planed in the others,
except in juvenals of boliviensis, sublimis and amicus. The horizon-
tal outline of the cusps varies from ovate to triangulate whether in
different species or within the same species. The enamel pattern of
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 223
the second molar may be 8-shaped, modified S-shaped, or some inter-
mediate design. The procingulum of second upper molar is present
in adults of most species, weakly developed in P. sublimis, and con-
siderably reduced in the P. darwini complex.
Taxonomy
All generic synonyms were based, originally, on single species.
Paralomys Thomas and Loxodontomys Osgood were frankly proposed
for a species each of Phyllotis. Graomys Thomas also proves to be
monotypic, though it was first believed to include four "species."
Auliscomys Osgood was set up on the basis of a comparison of its
genotype, P. pictus, with Phyllotis darwini. Two other species, P.
sublimis and P. boliviensis, were also referred to Auliscomys, but
Osgood 's definition of the genus excludes them. Relationships be-
tween each of the genotypes as well as the remaining species (edithae
and hypogaeus not seen and excepted) are about the same, though not
in the same order. As simple species of the genus Phyllotis, the status
of each vis-a-vis the others remains exactly the same. Subgeneric
names in this case are superfluous complications.
224
FIG. 59. Species of I'hylloti*. Side view of skulls of a, I', griseoflavus; b,
P. darwini; c, P. micropus; d, P. sublimin; e, P. pictun; f, P. bolirienxis. Vertical-
incisive, molar and basal-incisive planes shown by white line (cf. pp. 107 108).
FIG. 60. Species of Phyllotis and Mystromys. Mandibles of a, P. griseoflavus;
b, P. darwini; c, P. micropus; d, P. sublimis; e, P. pictus; f, P. boliviensis; g, My-
stromys albicaudatus.
226
.B-2
o
II
o .
o _J
. V,
'_ s:
c S
r. ~
D..S
cl
C -y.
227
FIG. 62. Side view of skulls of a, Phyllotis darwini; b, Galenomys garleppi;
c, Chinchillula sahamae; d, Euneomys chinchilloides. Vertical-incisive, molar and
basal-incisive planes shown by white lines. (About X 1 HO
228
FIG. 63. Mandibles of a, I'hyllotis darwini; b, Galenomu* garlcppi; c, Andi-
nomys edax; d, Chinchillula sahamae; e, Euneomyx chinchilloides. Relationship
of incisor tips to molar plane shown by white line (cf. p. 108).
229
FIG. 64. Dorsal and ventral aspects of skull of a, Mystromys albicaudatus;
b, Phyllotis darwini. See comparisons in text, p. 221. (About X 1H-)
230
FIG. 65. Side view of a, Mystromys albicaudattis; b, Phyllotis darmni. See
comparisons in text, p. 221. (Slightly more than natural size.)
FIG. 66. Palate and right upper molars of a, Zygodonlomys brevicauda; b,
Mystromys albicattdatitx; c, Phyllolis darmni. See comparisons in text, p. 221.
231
Q,
232
FIG. 68. Right upper molars, unworn and worn of a, b, PhyllotiK danrini;
c, d, P. micropus.
FIG. 69. Right upper and left lower molars of a, Phyllotix darwini; b, Galenomt/x
garleppi; c, Andinomyx edax; d, Chinchillula sahamae; e, Euneomyx chinchilloides.
233
234 FIELDIANA: ZOOLOGY, VOLUME 46
Phyllotis darwini Complex
Distribution
(Figures 57, 70)
Savannas, scrublands and deserts from the Ecuadorian Andes
south through the Andes and along the Pacific coast to the Straits
of Magellan and to the Atlantic in the Patagonian region.
Definition
The Phyllotis darwini complex consists of the usual complement
of broadly defined clinal subspecies, a pair of sympatric subspecies,
and a group of ill-defined species or near species which are not cer-
tainly recognizable as taxons in allopatry but are not known to inter-
breed in sympatry.
The geographic relationship of the members of the complex is
discussed elsewhere under the heading Sympatry and Allopatry
(p. 31).
Characters
External. Size moderate to nearly as large as P. griseoflavus;
tail from approximately one-third less to two-fifths more than com-
bined head and body length, sharply bicolor or slightly paler beneath
than above, thinly to well haired but never markedly bushy, tip more
or less pencilled; hind feet normal, soles naked except at heel, plantar
tubercles well developed; ears moderate to large in size, length, from
notch, rarely, if ever, as long as hind foot with claw; small pale post-
auricular patches often present. Upper parts of body buffy or ochra-
ceous to dark brown, more or less mixed with black; head and sides
of body with less black; ochraceous lateral line present or absent;
underparts from sharply defined whitish to gray or from plumbeous
washed with buff to brown and hardly or not at all defined from
sides; base of hairs always dark; a pectoral streak or mid ventral line
often present.
Cranial. Interorbital region generally narrow, the sides con-
cave, parallel or posterior half slightly to moderately divergent;
borders square or slightly pinched upward, sometimes beaded or
provided with narrow ledges; zygomata usually parallel-sided or
convergent anteriorly, rarely well expanded, their greatest breadth
less than distance between posterior tips of nasals and anterior
FIG. 70. Distribution of the species and subspecies of the Phyllolis danrini
complex.
235
236 FIELDIANA: ZOOLOGY, VOLUME 46
border of supraoccipital; anterior border of infraorbital plate plane
or slightly concave, the upper corner rounded, square, or pointed,
never produced as a conspicuous spinous process; incisive foramina
well opened; posterior border of palate square, or rounded and
with or without a median spinous process; posterolateral palatal
pits variable in size and position relative to anterior border of
mesopterygoid fossa; bullae moderately inflated, their antero-
posterior length, less tubes, approximately equal to or less than
alveolar length of molar row; outer side of mandible with slightly
projecting capsule for encasing base of incisor.
Dental. Upper incisor ungrooved, opisthodont (fig. 19, A) 1 but
combined width of cutting edges less than alveolar length of m 1 ;
molar rows parallel-sided or slightly convergent posteriorly; upper
and lower first molars 4-rooted; molars hypsodont, crowns of upper
plane, cusps ovate or sub triangular in outline; crowns of unworn
lower molars slightly terraced ; procingulum of m^ usually reduced,
the first primary fold shallow and well defined in Juvenal, often
persistent in adult; moderately worn m^ with 8-shaped or S-shaped
enamel pattern; a vestigial mesoloph sometimes present in m 1 "^;
m^ with first minor and primary folds present in unworn, present
or absent in worn condition.
Comparisons
Because of the community of their characters and the paral-
lelisms in their individual and local variations, all members of the
Phyllotis darwini complex are best compared as a unit with other
species of the genus. Small, pale, long-tailed members of the group
resemble large, similarly colored representatives of Phyllotis amicus;
and small, pale, short-tailed individuals are superficially like P.
boliviensis. Large, dark, short-tailed examples could be confused
with P. micropus and large, pale, long-tailed group members re-
semble P. griseoflavus. Externally, the P. darwini complex is dis-
tinguished from P. amicus by larger size, tail generally shorter
relative to head and body length, ears proportionately smaller and
not as long as hind foot including claw; from P. micropus by tail
relatively longer, hairier, pencilled, more distinctly bicolor, and pel-
age of body glossy and adpressed; from P. griseoflavus by under-
parts grayer, less sharply defined, with hairs of throat and neck
1 Pearson (1958, pp. 413 ff.) describes the upper incisors of Phyllotis darwini
as orthodont.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 237
slaty basally, tail usually shorter, less hairy basally, ears shorter;
from P. boliviensis by over-all larger size and usually longer tail, pre-
auricular patches absent, postauricular patches absent or incon-
spicuous.
Dentally, members of the darwini complex, excepting P. darwini
wolffsohni, differ from all congeners by the greater reduction of
procingulum of m^" 3 - and postcingulum of m^^, with corresponding
first primary folds and minor folds of worn teeth reduced or ob-
solete (fig. 67); these folds of the procingula are nearly always
well developed in P. darwini wolffsohni (fig. 85, rf-/). The com-
paratively long, narrow skull, slightly expanded zygomata, usually
parallel- or concave-sided interorbital region, and moderately sized
tympanic bullae (figs. 58-60) are cranial characters that singly or in
combinations serve to distinguish members of the darwini complex
from the species with which comparisons have been made. Such
members of the darwini complex as P. darwini wolffsohni and P. d.
caprinus (fig. 83) with more or less beaded and divergent-sided
interorbital regions are distinguished by their narrower interorbital
width as compared with P. griseoflavus and P. amicus with sim-
ilarly shaped skulls.
238 FIELDIANA: ZOOLOGY, VOLUME 46
EXPLANATION OF FIGURE 71
Phyllotis in Ecuador: collecting localities and collectors.
Type localities in boldface.
Phyllotis haggardi (1-16)
1. Mojanda (Mount), Pichincha. Natives per L. Soderstrom at 8000-13,000
feet.
2. Perucho, Pichincha. Natives per L. Soderstrom.
2. Puellaro, between Perucho and Guaillabamba, Pichincha. Natives per L.
Soderstrom at 7500 feet.
3. Guaillabamba, Pichincha. Natives per L. Soderstrom at 8000-9000 feet.
4. Puembo, Pichincha (2542 meters). Native per L. Soderstrom at 8000 feet.
5. Pichincha (Mount), Pichincha. Type locality of haggardi; F. Mena at
3800 meters; M. Olalla between 3000 and 4000 meters; natives per L. Soder-
strom between 3000 and 4000 meters.
5. Garzon (Hacienda), southern foot of Mount Pichincha, Pichincha. S. N.
Rhoads at 12,000 feet.
6. Quito, Pichincha (2817 meters). Natives per L. Soderstrom.
6. Jiron, Pichincha. Natives per L. Soderstrom at 9400 feet.
7. Saloya, Pichincha. F. Mena per Leopoldo Gomez at "1100 meters."
7. "Galaya, Cotopaxi."= Saloya, Pichincha.
8. Papallacta, Napo-Pastaza (3156 meters). Native per L. Soderstrom.
9. Guamani, Pichincha (3400 meters) . Record ex Pearson (1958, p. 443) at
11,000 feet.
10. Antisana (Mount), Pichincha. W. Richardson at 12,000 feet; G. H. H.
Tate at 13,500-15,000 feet; Clark Mclntyre at 3500 meters; natives per
L. Soderstrom at 12,000 feet.
11. Corazon (Mount), Pichincha. Natives per L. Soderstrom.
12. Illiniza (Mount), Cotapaxi. Native per L. Soderstrom.
13. Chimborazo (Mount), Chimborazo. A. Mena at 4000-4200 meters.
14. Urbina, Chimborazo (3700 meters). G. H. H. Tate.
15. Pallatanga, Chimborazo (1550 meters). Type locality of elegantulus; C.
Buckley.
16. Contrayerbas, Azuay. Type locality of fuscus; G. H. H. Tate at 11,000
feet.
Phyllotis andium (17-24)
17. Banos, Tungurahua. Record ex Pearson (1958, p. 441) at 5800 feet.
18. Punin, Chimborazo. About 10 kilometers south of Riobamba; G. H. H.
Tate at 9000 feet.
18. Rfobamba, Chimborazo. Record ex Pearson (1958, p. 441) at 9900 feet.
19. Pauichi (Paujchi), Chimborazo or Canar. Tate, Wickenheiser. "Half day
by pack mule from Huigra on the Canar trail."
20. Canar, Canar. Type locality of andium; P. O. Simons at 2600 meters.
21. Cuenca, Azuay (2 53' S., 78 59' W.). Record ex Pearson (1958, p. 441)
at 7200 feet.
21. Guishapa, Azuay (2 59' S., 78 57' W.). Record ex Pearson (1958, p. 441)
at 6600 feet.
22. Sigsig, Azuay. Record ex Pearson (1958, p. 441) at 8500 feet.
23. Yunguilla Valley, Azuay. H. Cuestas at "1500 meters."
24. Guachanama, Loja. Type locality of fruticicolns; H. E. Anthony at
9050 feet.
Phyllotis haggordi
andium
FIG. 71. Collecting localities of Phyllotix haggardi and P. andium in Ecuador.
See opposite page for explanation.
239
Pnyllotis and/urn
haggard/
darwint limatus
" post i cat is
i 1
FIG. 72. Collecting localities of Phyllotis andium. Shaded areas show approxi-
mate ranges of P. haggardi and some subspecies of P. darwini in Peru. See oppo-
site page for explanation.
240
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 211
EXPLANATION OF FIGURE Tl
Phtjllotis andium: collecting localities and collectors.
Type localities in boldface.
ECUADOR
17-24. See explanation of figure 71 (p. 238) for names of localities.
PERU
25. Ayavaca, Piura (2750 meters). C. Kalinowski.
26. Huancabamba, Piura (1960 meters). C. Kalinowski.
27. Chongoyape, Lambayeque (240 meters). -C. Kalinowski.
27. Cabache ( = Cayache?), Lambayeque (460 meters). About 12 kilometers
northeast of Chongoyape; C. Kalinowski.
28. Concha, Amazonas. North of Chachapoyas; R. W. Hendee at 8000-9500
feet.
29. Condechaca, Amazonas (1550 meters). About 15 kilometers south of
Chachapoyas; R. W. Hendee at 7000 feet.
29. Chachapoyas, Amazonas (2398 meters). W. H. Osgood and M. P. Ander-
son; H. Watkins at 7500 feet.
30. Molinopamba, Amazonas (2350 meters). R. W. Hendee.
31. TAMBO CARRIZAL, Amazonas. Type locality of tamborum; W. H.
Osgood and M. P. Anderson at 5000 feet.
32. San Pedro, Amazonas. About 12 kilometers northeast of Leimabamba;
H. Watkins between 8600-9400 feet.
32. Leimabamba, Amazonas (2500 meters). R. W. Hendee.
33. UTCUBAMBA (Rio), 51 miles above Chachapoyas, Amazonas.
Type locality of stenops; W. H. Osgood and M. P. Anderson at 8000 feet;
R. W. Hendee.
34. Celendfn, Cajamarca (2500 meters). R. W. Hendee.
35. Limon (Hacienda), Cajamarca. W. H. Osgood at 3000 feet.
36. Cajamarca, Cajamarca (2750 meters). W. H. Osgood and M. P. Ander-
son; R. W. Hendee.
37. Llagueda (Hacienda), Libertad. W. H. Osgood at 6000 feet.
37. Otuzco (mountains near), Libertad. W. H. Osgood and M. P. Anderson
at 10,000 feet.
38. Macate, Ancash. M. P. Anderson at 9000-10,000 feet.
39. Yungay, Ancash (2335 meters). C. Kalinowski.
40. Huaras, Ancash (3091 meters). C. Kalinowski at 3050 meters.
40. Quilcayhuanca (Quebrada), Ancash. Northeast of Huaras; C. Kalinowski
at 4000 meters.
41. Pira, Ancash. R. W. Hendee at 13,000 feet.
42. Catac (Hacienda), Ticapampa, Ancash. C. Kalinowski at 3500 meters.
43. Llata, Huanuco. R. W. Hendee at 11,000 feet.
44. Cullcui, Huanuco. J. T. Zimmer at 10,400 feet.
45. Ambo, Huanuco (2152 meters). E. Heller.
46. Huarcs, Lima. O. P. Pearson at 11,500-12,000 feet.
47. Canta, Lima.- O. P. Pearson at 8800 feet.
48. Surco, Lima (2050 meters). M. Puestas.
48. Santa Eulalia, Lima. O. P. Pearson at 3500 feet.
49. Matucana, Lima (2336 meters). J. T. Zimmer.
242 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 72 (continued)
49. San Bartolom6 Station, Lima. About 12 kilometers southwest of Matu-
cana; O. P. Pearson at 5200 feet.
49. San Mateo, Lima. About 12 kilometers northwest of Matucana; O. P.
Pearson at 9500 feet.
49. Zarate, Lima. About 5 kilometers southwest of Matucana; O. P. Pearson
at 9000 feet.
50. Casapalca, Lima. O. P. Pearson at 13,200-14,000 feet.
50. Villavista, Lima. About 7 kilometers southwest of Casapalca; 0. P. Pear-
son at 12,200 feet.
EXPLANATION OF FIGURE 73
Phyllotis darwini in Peru: collecting localities and collectors.
Type localities in boldface.
Phyllotis darwini definitus (1)
1. Macate, Ancash. M. P. Anderson at 9000 feet.
Phyllotis darwini limatus (2-14)
2. Huacho, Lima (30 meters). J. J. von Tschudi.
3. Lima, Lima, 156 meters. Capital of Peru; no collecting records.
4. Nana, Lima. O. P. Pearson at 2200 feet.
5. Chosica, Lima. P. O. Simons; C. C. Sanborn at 3000 feet; O. P. Pear-
son at 3500 feet.
5. Rimac Valley. O. P. Pearson at 4400 feet.
6. Santa Eulalia, Lima. J. T. Zimmer; 0. P. Pearson at 4000 feet.
7. Huinco, Lima.
8. San Bartolome Station, Lima. O. P. Pearson at 5200 feet.
8. Verruga Canyon. Dr. Tyzzer.
9. Surco, Lima. O. P. Pearson at 6000 feet.
9. Oscollo, Lima. M. Puestas.
10. La Palma, Lima.
11. San Jacinto, lea, lea. C. C. Sanborn.
12. Atico, Arequipa. C. B. Koford at 50 feet.
13. Tambo, Arequipa.
14. Chucarapf, Arequipa. C. B. Koford at 300 feet.
Phyllotis darwini posticalis (15-42)
15. Huariaca, Pasco. R. W. Hendee at 9000 feet.
16. Carhuamayo, Junfn. C. C. Sanborn at 14,500 feet.
17. Junm, Junin (4133 meters). M. P. Anderson.
18. Oroya = La Oroya, Junin (3720 meters). Type locality of abrocodon;
R. W. Hendee; M. P. Anderson.
19. Galera, Junin. Type locality of posticalis; P. 0. Simons at 4800 meters.
20. Casapalca, Lima. O. P. Pearson at 13,200-14,000 feet.
21. Mantaro (Rfo), Huancavelica. 0. P. Pearson at 8500 feet.
22. Piso (Hacienda), Locroja, Huancavelica. C. Kalinowski at approxi-
mately 3100 meters.
23. Mayoc, Huancavelica. C. Kalinowski at approximately 2500 meters.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 243
Phyllotis d
defmifus
limatus
o posfico//
mogisfer
ropes fris
FIG. 73. Collecting localities of the subspecies of Phyllotis darmini in southern
Peru. The approximate range of P. d. rupestris is shaded. P. d. rupestris and
P. d. magister are independent offshoots of P. d. posticalis that have become
sympatric.
Explanation of Figure 73 (continued)
24. Huancavelica, Huancavelica (3716 meters). C. Kalinowski at 3680
meters.
25. Lircay, Huancavelica (2714 meters). C. Kalinowski at 3310 meters.
26. San Jenaro, Santa Ine"z, Huancavelica. C. Kalinowski at 4760 meters.
27. Polanco, Tambo, Ayacucho. C. Kalinowski.
28. Ayacucho, Ayacucho.- O. P. Pearson at 9500 feet.
29. Puente Pajonal, Ocros, Ayacucho. C. Kalinowski at 1900 meters.
30. Puquio, Ayacucho. O. P. Pearson at 14,600 feet (35 kilometers ENE of
Puquio), 13,500 feet (15 kilometers ENE); C. B. Koford at 14,500 feet.
31. Palmira (Hacienda), Andahuaylas, Apurimac. C. Kalinowski at 2200
meters.
32. Occobamba Valley, Cusco. E. Heller at 9100 feet.
32. Tocopoqueu, Cusco. E. Heller at 9100 feet.
33. Ollantaytambo, Cusco. E. Heller at Occobamba Pass, 15 kilometers
north of Ollantaytambo, 9300 feet.
34. Macchu Picchu, Cusco (2331 meters). E. Heller at 6000-13,000 feet.
35. Chospioc, Cusco. E. Heller at 10,000 feet.
35. Huarocondo, Cusco. E. Heller at 10,850 feet.
36. Urco (Hacienda), Calca, Cusco (3000 meters). E. Heller; J. M. Schmidt.
36. Paullo Grande, Calca, Cusco. C. Kalinowski at 2900 meters.
244 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 73 (continued)
37. Ampay, Pisac, Cusco. C. Kalinowski at 3500 meters.
38. Puquiura, Cusco. E. Heller at 9500 feet.
39. Sacsahuaman, Cusco, Cusco. A pre-Columbian fortress overlooking
Cusco; C. C. Sanborn at 11,500 feet.
39. Cusco, Cusco (3496 meters). C. C. Sanborn.
39. Fundo Perayoc, Cusco. I. Ceballos.
40. Ocongate, Cusco (3465 meters). C. Kalinowski.
41. Ccolini, Marcapata, Cusco. C. Kalinowski at 3900 meters.
42. Limbani, Puno. C. B. Koford at 13,000 and 15,000 feet.
Phyllotis darwini magister (43-48, all sympatric with P. d. rupestris).
43. Yura, Arequipa. J. M. Schmidt at 8000 feet.
44. Misti (Mount), Arequipa (5860 meters). P. O. Simons at 2500 meters.
45. Arequipa, Arequipa. P. O. Simons at 2300 meters; H. E. Anthony
and G. Ottley.
46. Tingo, Arequipa. Southeastern outskirts of Arequipa; G. H. H. Tate at
7500 feet.
46. Chihuata, Arequipa. M. and C. B. Koford at 10,000 feet.
47. Torata (Rfo), Moquegua. 15 kilometers northeast of Torata; A. K. and
O. P. Pearson at 11,200 feet.
48. Tarata, Tacna. A. K. and O. P. Pearson at 11,000-12,800 feet.
EXPLANATION OF FIGURE 74
Phyllotis darwini: locality records and collectors of subspecies of P. darwini in
southern Peru, Bolivia, northern Chile and northern Argentina.
Phyllotis darwini rupestris (1-93)
PERU
1. Ongoro, Valle de Mages, Arequipa. C. C. Sanborn.
2. San Ignacio, Arequipa. O. P. Pearson at 13,000 feet.
2. Cailloma, Arequipa (4330 meters). P. 0. Simons; C. C. Sanborn and
J. M. Schmidt at 14,500 feet.
3. Sibayo, Arequipa. 0. P. Pearson at 11,500 feet.
4. Pulpera, Arequipa.
5. Huaylarco, Arequipa. A. K. Pearson at 15,300 feet; C. B. Koford at
15,000 feet.
6. Imata, Arequipa. M. and C. B. Koford at 14,500 feet.
7. Sumbay, Arequipa. C. C. Sanborn and J. M. Schmidt at 13,500 feet.
8. Yura, Arequipa. J. M. Schmidt at 8000 feet.
9. Arequipa, Arequipa (2335 meters). P. O. Simons; H. E. Anthony and
G. Ottley; A. K. and 0. P. Pearson at 8800 feet.
10. Balneario de Jesus, Arequipa. C. C. Sanborn at 8900 feet.
11. Misti, Arequipa. P. 0. Simons.
12. Salinas, Arequipa. C. C. Sanborn at 14,000 feet; C. B. Koford at 14,200
feet.
13. Asillo, Puno. C. C. Sanborn; C. B. Koford at 13,000 feet.
13. Osila, Puno. See Asillo.
14. Arapa, Puno. M. Koford at 12,600 feet.
15. Juliaca, Puno (3825 meters). J. M. Schmidt at 12,500 feet; M. Koford.
16. Umayo, Puno. C. B. Koford at 12,700 feet.
o rupesfris i . j
wolffsohni j
x coprinus 104 - no
Phyllotis osi/oe
osiloe
p/ioeus
^B nogo/oris
fucumonus
FIG. 74.- Collecting localities of the subspecies of Phi/llolix dnnrini in southern
Peru, Bolivia, and northern Chile and Argentina. Shaded areas show the approxi-
mate range of each of the subspecies of sympatric Phyllotis osilar.
245
246 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 74 (continued)
17. 82 kilometers west of Puno. A. K. and O. P. Pearson at 14,000 feet.
18. Tincopalca, Puno. C. B. Koford at 13,500 feet.
19. Occomani, Puno. E. Zuniga.
20. Puno, Puno (3822 meters). M. R. Portugal; A. K. and 0. P. Pearson and
C. B. Koford at 13,000 feet.
21. Chucuito, Puno. C. C. Sanborn.
22. San Antonio de Esquilache, Puno. C. C. Sanborn at 15,000 feet.
23. Collacachi, Puno. C. C. Sanborn at 12,000 feet.
24. Have, Puno. O. P. Pearson at 12,600 feet.
25. Juli, Puno. O. P. Pearson at 12,500-12,700 feet.
26. Pairumani, Puno (4062 meters). 0. P. Pearson at 12,800 feet; C. B.
Koford at 13,000 feet.
27. Sorapa, Puno. H. E. Anthony and G. Ottley.
28. Pomata, Puno. 0. P. Pearson at 13,500 feet.
29. Yunguyo, Puno. C. C. Sanborn at 13,000 feet.
30. Huacullani, Puno. C. C. Sanborn.
31. Santa Rosa de Juli, Puno. O. P. Pearson at 14,000 and 15,000 feet.
32. Caccachara, Puno. 0. P. Pearson at 15,200 and 16,000 feet.
33. Mazocruz, Puno. C. B. Koford at 14,300 feet.
34. Rfo Santa Rosa, Puno. A. K. and O. P. Pearson at 14,400 feet; C. B.
Koford.
35. Pisacoma, Puno. C. C. Sanborn at 13,200 feet.
36. Pampa de Ancomarca, Puno. A. K. and 0. P. Pearson at 14,200 feet.
37. Torata, Moquegua. A. K. Pearson at 9400 feet, 10 kilometers NE.; A. K.
and O. P. Pearson at 11,200 feet, 15 kilometers NE.
38. Tala, Moquegua. A. K. Pearson at 13,700 feet.
39. Volcan Tutupaca, Moquegua.
40. Lago Suche, Moquegua. O. P. Pearson at 14,500 feet; A. K. Pearson at
14,600 feet, 5 kilometers E.
41. Lago Viscacha, Moquegua. A. K. Pearson at 14,900 feet.
42. Tarata, Tacna. A. K. and O. P. Pearson at 11,500 feet, 2 kilometers N.;
at 12,200 feet, 3 kilometers N.; at 12,800 feet, 4 kilometers N.; A. K. Pear-
son at 13,200 feet, 4.5 kilometers N.; A. K. and O. P. Pearson at 13,500 feet,
5 kilometers N.; 14,600 feet, 20 kilometers NE.; O. P. Pearson at 15,200
feet, 25 kilometers NE.; C. B. Koford, 13,000 feet, 8 miles NE.
43. Nevado Livine, Tacna.
CHILE
44. Parinacota, Tarapaca. Type locality of osgoodi Mann and chilensis
Mann; G. Mann.
45. Putre, Tarapaca (4560 meters). G. Mann; C. C. Sanborn at 11,600 feet.
46. Codpa, Tarapaca (2109 meters). G. Mann.
46. Timar, Parinacota, Tarapaca. Type locality of chilensis Mann.
47. Esquina, Tarapaca. G. Mann.
48. Caritaya, Tarapaca. C. B. Koford at 12,000 feet.
49. Tarapaca, Tarapaca (1350 meters). G. Mann.
50. Ojos de San Pedro, Antofagasta. M. and C. B. Koford at 12,500 feet.
51. San Pedro, Antofagasta (2436 meters). F. Philippi; type locality of
glirinus Philippi, lanatus Philippi.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 247
Explanation of Figure 74 (continued)
52. San Pedro, 20 miles E., Antofagasta (3223 meters). C. C. Sanborn.
53. Toconce, Antofagasta. M. and C. B. Koford at 14,000 feet.
54. Tatio Geysers, Antofagasta. C. B. Koford at 14,000 feet.
55. Cobija, Antofagasta ("high mountains" of). Type locality of rupestris
Gervais; M. Gaudichaud (voyage La Bonite).
56. Antofagasta, Antofagasta. Type locality of capita Philippi.
57. Paposa, Antofagasta.
58. Mill-so Parado, Taltal, Antofagasta (sea level). -F. Philippi.
58. Muelle de Piedra, east of Taltal. Not located; see Hueso Parado.
59. Vallenar, Atacama.
60. Domeyko, Atacama (778 meters). C. C. Sanborn.
BOLIVIA
61. La Paz, La Paz. Specimens from 20 miles south; O. P. Pearson at 13,000
feet.
62. Cosmini, La Paz. 14,400 feet.
63. Estacion Perez, La Paz. F. Steinbach at 3913 meters.
63. General Prez, La Paz. See Estacion Perez.
64. Esperanza, Pacajes, La Paz. F. Steinbach at 4200 meters.
65. Sahama (Mt.), Oruro. F. Steinbach at 4350 meters.
66. Oruro, Oruro (3700 meters). P. O. Simons.
67. Oruro, 40 miles S., Oruro. O. P. Pearson at 12,000 feet.
68. Chianta, Oruro. At 12,000 feet.
69. Tin Tin, Cochabamba. J. Steinbach.
70. Sucre, Chuquisaca.
71. Potosf, Potosf (4020 meters).
72. Potosf, 20 miles S., Potosf. O. P. Pearson at 12,300 feet.
73. Uyuni, Potosi. Type locality of arenarius Thomas; 0. P. Pearson at
12,600 feet; P. 0. Simons at 3670 meters.
74. Lipez (=San Antonio de Lipez), Potosf (4510 meters). E. Budfn at 4500
meters.
75. Villazdn, Potosf. O. P. Pearson at 11,500 feet, 5 miles N. and 25 miles N.
76. Camataquf, Tarija. O. P. Pearson at 11,500 feet, 25 miles SSE.
77. Sama, Tarija. E. Budin at 4000 meters.
ARGENTINA
78. Abrapampa, Jujuy (3475 meters). E. Budfn at 3500 meters.
79. Cerro Casabindo, Jujuy. E. Budfn at 4000 meters.
80. Tres Cruces, Jujuy (3632 meters). E. Budfn at 4000 meters.
81. Sierra de Zenta, Jujuy. E. Budfn at 4500 meters.
82. Tilcara, Jujuy. O. P. Pearson at 8500 feet.
83. Alfarcito, Jujuy. E. Budfn.
84. La Laguna, Sierra de Zenta, Jujuy. J. Yepes at 4500 meters.
84. Cerro de Lagunita, Jujuy.- E. Budfn at 4500 meters.
85. San Antonio de los Cobres, Salta. E. Budfn at 3700 meters.
85. San Antonio, Los Andes. See San Antonio de los Cobres.
86. G. M. Sola, Salta. E. Budfn at 2500 meters.
87. Incamayo, Salta.
88. Salar de Antofalla, Los Andes ( = Catamarca).
89. Pasto Ventura, Catamarca.
248 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 74 (continued)
90. Laguna Blanca, Catamarca. Type locality of oreigenus Cabrera; E.
Budin at 3200 meters; J. Mogensen at 3200 meters; Weiser.
91. Lago Helado, Catamarca.
92. Otro Cerro, Catamarca. Type locality of ricardulus Thomas; E. Budin
at 3000 meters.
93. Chumbicha, Catamarca. E. Budfn at 500 meters.
Phyllotis darwini wolffsohni (92-103)
BOLIVIA
92. Tapacari, Cochabamba. O. P. Pearson at 9000 feet, 15 miles E.
93. Parotani, Cochabamba. L. E. Miller and H. S. Boyle at 8800 feet.
94. Cochabamba, Cochabamba (2464 meters). J. Steinbach at 2700 meters.
94. Taquina, Cochabamba. Suburb of Cochabamba; J. and F. B. Steinbach
at 2700-2750 meters.
95. Cuchicancha, Cochabamba. L. E. Miller and H. S. Boyle at 11,000 feet.
96. Tiraque, Cochabamba. F. B. Steinbach at 3200 meters.
97. Punata, Cochabamba. O. P. Pearson at 10,000 feet, 8 miles NE., and
10,500 feet, 10 miles NE.
98. Arani, Cochabamba. At 9000 feet.
99. Pocona, Cochabamba. F. B. Steinbach at 2700 meters.
100. Totora, Cochabamba. At 8500 feet.
101. Comarapa, Santa Cruz. 0. P. Pearson at 7500 feet.
102. Guadelupe, Santa Cruz. Marzan and Machiavello.
103. Tomina, Chuquisaca. R. M. Gilmore at 2200 meters.
Phyllotis darwini caprinus (104-110)
BOLIVIA
104. Camargo, Chuquisaca.- O. P. Pearson at 8500 feet.
105. Camataqui, Tarija. 0. P. Pearson at 8500 feet, 20 miles SSE.
106. Tarija, Tarija. 0. P. Pearson at 6700 feet.
107. Yuruma, PotosL E. Budfn at 2200 meters; 0. P. Pearson at 10,500 feet.
ARGENTINA
108. Sierra de Zenta, Jujuy. E. Budin at 4500 meters.
109. Humahuaca, Jujuy. At 7700 feet.
110. Tilcara, Jujuy. L. E. Miller and H. S. Boyle at 8000 feet; O. P. Pearson
at 8000 feet.
110. Maimara, Jujuy. E. Budfn at 2230 meters.
EXPLANATION OF FIGURE 75
Phyllotis darwini: locality records and collectors of subspecies of P. darwini
in Chile and Argentina (continued from fig. 74).
Phyllotis darwini rupestris (1-29)
ARGENTINA
1. Lago Helado, Catamarca. See no. 91, fig. 74.
2. Otro Cerro, Catamarca. Type locality of ricardulus Thomas; E. Budin
at 3000 meters.
3. Chumbicha, Catamarca (415 meters). E. Budin at 500 meters.
Phyllotis darwini
o rupesfris i n
darwini to H
m fu/vescens j
xonf/iopygus M
-
.'-- / o o
FIG. 75.^ Collecting localities of the subspecies of Phyllolix darwini in Argentina
and Chile.
249
250 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 75 (continued)
4. La Invernada, Cadena Famatina, La Rioja. E. Budfn at 3800 meters.
5. Potrerillos, La Rioja (2500 meters). E. Budfn.
6. Chilecito, La Rioja. J. Yepes at 1000 meters.
7. Puesto Viejo, La Rioja. J. Yepes at 2500 meters.
8. Las Piriquitas, La Rioja. J. Yepes.
9. San Antonio, La Rioja. J. Yepes at 2700 meters.
10. Sierra de Tontal, San Juan. E. Budfn.
11. Angaco Sud, San Juan.
12. Los Sombreros, San Juan. E. Budfn at 2700 meters.
13. Pedernal, San Juan.
14. Puente del Inca, Mendoza (2720 meters). E. Budfn; H. E. Anthony and
G. Ottley.
15. Punta Vacas, Mendoza (2385 meters). Type locality of vaccarum
Thomas; P. O. Simons; E. Budfn at 2300-2500 meters.
15. Las Vacas, Mendoza. See Punta Vacas.
16. Canada Colorada, Mendoza (440 meters). J. Yepes.
17. Malargue, Mendoza (1450 meters). J. Yepes.
18. Chos Malal, Neuquen (1395 meters). E. Budfn.
19. Las Lajas, Neuquen (710 meters). E. Budfn.
20. Quilquihue, Neuquen. E. Budfn.
21. Collon Cura, Neuquen. E. Budfn.
CHILE
22. Vallenar, Atacama.
23. Domeyko, Atacama (778 meters). C. C. Sanborn.
24. Banos del Toro, Coquimbo (3258 meters). C. C. Sanborn at 10,600 feet.
25. Paihuano [Paiguano], Coquimbo. C. C. Sanborn at 3300 feet.
26. Rfo Blanco, Santiago. R. Barros V., at 1540 meters.
27. Bocatoma, Santiago (1800 meters). Type locality of wolffhuegeli Mann;
G. Mann.
27. Lo Valdes, Santiago. W. and G. Mann.
28. Rfo Maule, 14 km. above Curillinque, Talca. C. C. Sanborn.
29. Arroyo del Valle, Talca. C. C. Sanborn.
Phyllotis darwini darwini (30-54)
CHILE
30. La Sirena, Coquimbo. Type locality of griseoflavus Philippi.
30. Romero, Coquimbo. C. C. Sanborn.
31. Coquimbo, Coquimbo. Type locality of darwini Waterhouse; C. Darwin.
32. Fray Jorge, Coquimbo.
33. Illapel, Coquimbo. Type locality of illapelintis Philippi.
34. Choapa, Coquimbo. Type locality of campestris Philippi.
35. Alicahue, Aconcagua. J. A. Wolffsohn.
36. Longotoma, Aconcagua. J. A. Wolffsohn at 200 meters.
37. La Ligua, Aconcagua. Type locality of platytarsus Philippi; C. C.
Sanborn.
38. Papudo, Aconcagua. J. A. Wolffsohn at 100 meters; C. S. Reed; C. C.
Sanborn.
39. Los Agostinos, Aconcagua. J. A. Wolffsohn.
40. Las Rojas [ = Lo Rojas], Quillota, Valparaiso. J. A. Wolffsohn at 150
meters.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 251
Explanation of Figure 75 (continued)
41. Buen Retire, Valparaiso. J. A. Wolffsohn at 250-300 meters.
41. Las Hijuelas, Valparaiso.
41. La Calera, Valparaiso. J. A. Wolffsohn; C. S. Reed.
42. Palmilla, Valparaiso. J. A. Wolffsohn at 300 meters.
43. Olmu6, Valparaiso (152 meters). J. A. Wolffsohn.
44. Quilpue", Valparaiso. J. A. Wolffsohn at 100 meters.
45. Valparaiso, Valparaiso.
46. La Laguna, Valparaiso.
47. Batuco, Santiago.
48. San Cristobal, Santiago. F. C. C. Platt.
48. Santiago, Santiago.
49. Puente Alto, Santiago.
50. Penalolen, Santiago.
51. Angostura, Santiago. Type locality of M us melanonotus Philippi.
52. Paine, Santiago; see Peine.
52. Peine, Santiago. -Type locality of dichrous Philippi and segethi Philippi.
53. Pilen Alto, Maule (250 meters). J. A. Wolffsohn; C. C. Sanborn.
54. Quirihue, Nuble.- C. C. Sanborn.
54. Coroney Ranch, Nuble. -Type locality of boedeckeri Osgood; C. C.
Sanborn.
Phyllotis darwini fulvescens (55)
CHILE
55. Piedra de Aiguilas, Sierra Nahuelbuta, Malleco. Type locality of
fulvescens Osgood; W. H. Osgood at 4000 feet.
55. Araucaria forest, Nahuelbuta, Malleco. H. E. Anthony and G. Ottley at
3700 feet.
Phyllotis darwini xanthopygus (56-68)
ARGENTINA
56. Pilcaneu, Rfo Negro. E. Budm at 1400 meters; H. E. Box.
57. Huanuluan, Rfo Negro. J. L. Peters at 3200-3600 feet.
58. Tecka, Chubut. H. E. Box.
59. Pico Salamanca, Comodoro Rivadavia.
60. Caprek Aike, Comodoro Rivadavia. C. Burmeister.
61. Basaltic Canyons (Arroyo Aike), Santa Cruz. O. A. Peterson.
62. Swan Lake ( = Lago de Los Cisnes), Santa Cruz. O. A. Peterson.
62. Arroyo Aike, see Swan Lake and Basalt Canyons. A. E. Colburn.
63. Rfo Chico (upper), Santa Cruz. O. A. Peterson; A. E. Colburn.
64. Lago Viedma, Santa Cruz (225 meters). J. R. Pemberton.
65. Puerto Deseado, Santa Cruz. C. Darwin.
65. Port Desire, see Puerto Deseado.
66. Santa Cruz, Santa Cruz. Type locality of xanthopygus Waterhouse;
C. Darwin; B. Brown, 30 miles south.
67. Rfo Coig, Santa Cruz. O. A. Peterson.
67. Rfo Coy, see Rfo Coig.
CHILE
68. Laguna Lazo, Magallanes.
252
FIELDIANA: ZOOLOGY, VOLUME 46
Phyllotis darwini posticalis
osilae phaeus
osilae
FIG. 76. Contact between Phyllotis osilae and P. darwini posticalis. Probable
origin of P. osilae from the ancestral form of P. daricini posticalis indicated by
broken-lined arrow.
EXPLANATION OF FIGURE 77
Phyllotis osilae: locality records and collectors.
Type localities in boldface.
Phyllotis osilae osilae (1-37)
PERU
1. Occobamba, Cusco. E. Heller at 9500 feet.
2. Macchu Picchu, Cusco. E. Heller at 12,000-14,000 feet.
3. Ollantaytambo, Cusco. E. Heller at 13,000 feet.
4. Huarocondo, Cusco. E. Heller at 10,850 feet.
5. Urco, Cusco. J. M. Schmidt at 9500-10,000 feet.
6. Santa Rosa de Ayaviri, Puno. O. P. Pearson at 12,800 feet.
7. Osilla, Puno. = Asilla.
7. Asillo, Puno. H. H. Keays at 12,000 feet; C. B. Koford at 13,000 feet.
8. Tirapata, Puno (3880 meters). H. H. Keays.
9. Azangaro, Puno (3859 meters). Ortiz de la Puente at 4020 meters.
10. Checayani, Puno.
11. Calacala, Puno. C. B. Koford at 13,000 feet.
12. Arapa, Puno. M. and C. B. Koford at 12,600 feet.
13. Umayo, Puno. M. Koford at 12,700 feet.
14. Isla Amantf, Lago Titicaca, Puno.
15. Vilque, Puno. 0. P. Pearson at 13,300 feet.
' .5 B Of I i
, N '"W )S" -. '
ii H* ;*'
Phyllotis osi/oe
osi/oe i - >'
o fucumonus >
phoeus ' - si
nogo/oris M
I S" /"**-; / ~
P/)y//ofis darwini
a posh'calis
limatus
ropes fri's
FIG. 77. Collecting localities of the subspecies of Phyllotix oxilae. Shaded
areas show approximate ranges of the subspecies of I'hyllotis darwini in southern
Peru, Bolivia, and northern Argentina and Chile. See opposite page for explanation.
253
254 FIELDIANA: ZOOLOGY, VOLUME 46
Explanation of Figure 77 (continued)
16. Occomani, Puno. C. C. Sanborn at 12,700 feet.
17. Puno, Puno (3822 meters). A. K. and O. P. Pearson at 13,000 feet; M. C.
Portugal.
18. Chucuito, Puno. C. C. Sanborn at 12,800 feet.
19. Pairumani, Puno.-C. B. and M. Koford at 13,000 feet; A. K. and O. P.
Pearson at 12,800 and 13,500 feet.
20. Juli, Puno. A. K. Pearson at 12,700 feet.
21. Pomata, Puno. A. K. and O. P. Pearson at 12,500 feet.
22. Yunguyo, Puno. C. C. Sanborn at 13,000 feet.
23. Huacullani, Puno. C. C. Sanborn at 12,700 feet.
BOLIVIA
24. Achacachi, La Paz. R. M. Gilmore at 3800 meters.
25. La Paz, La Paz (3720 meters).
26. Choro, Cochabamba. Type locality of lutescens; P. O. Simons at 3200-
3500 meters; F. Steinbach at 3500 meters.
27. Choquecamate, Cochabamba. P. O. Simons at 4000-4300 meters.
28. Colomi, Chapare, Cochabamba. F. Steinbach.
29. Tiraque, Cochabamba. Collected at 15 miles ESE.; O. P. Pearson at
10,500 feet.
30. Punata, Cochabamba. Collected 10 miles NE.; 0. P. Pearson at 10,500
feet.
31. Vacas, Cochabamba. J. Steinbach at 3800 meters.
32. Lagunillas, Potosf (3500 meters). P. O. Simons.
33. El Cabrado, Potosf. P. O. Simons at 3500 meters.
34. Tarija, Tarija. Collected 10 miles NW.; 0. P. Pearson at 8200 feet.
35. Pinos, Tarija. E. Budfn at 1700 meters.
ARGENTINA
36. Leon, Jujuy. E. Budin at 1500 meters; O. P. Pearson at 5800 feet.
37. Yala, Jujuy, mountains west of. W. H. Osgood at 10,000 feet.
Phyllotis osilae tucumanus (38-46)
ARGENTINA
38. Cienaga, Tucuman.
39. Tan del Valle, Tucuman. L. E. Miller and H. S. Boyle at 7000 and 9500
feet.
40. Cumbre de Mala Mala, Sierra de Aconquija, Tucuman. Type local-
ity of tucumanus; E. Dinelli at 3300 meters.
41. Cerro San Javier, Tucuman. E. Budfn at 2000 meters.
42. Norco, Vipos, Tucuman. E. Budfn at 1500-2000 meters.
43. Aconquija, Catamarca. J. Mogensen at 3000 meters.
44. Rfo Vallecito, Andalgala, Catamarca. J. Crespo at 2900 meters.
45. Otro Cerro, Catamarca. E. Budfn at 3000 meters.
46. Chumbicha, Catamarca. E. Budfn at 500-600 meters.
Phyllotis osilae phaeus (47-53)
PERU
47. Limbani, Puno. C. C. Sanborn at 11,000 feet; C. B. Koford at 11,500
and 13,000 feet.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 255
Explanation of Figure 77 (continued)
BOLIVIA
48. Sorata, La Paz (2657 meters). - H. E. Anthony and G. Ottley.
49. Tacacoma, La Paz. H. E. Anthony and G. Ottley.
50. Alaska Mine, La Paz. G. H. H. Tate at 13,700 feet.
51. Pongo, La Paz. G. H. H. Tate at 12,000 feet.
52. Aceramarca, La Paz. G. H. H. Tate at 10,800 feet.
53. Yanacachi, La Paz.
Phyllotis osilae nogalaris (54)
ARGENTINA
54. 1 1 mu, -i ill. i. Valle Grande, Jujuy. E. Budfn at 2000 meters.
256 FIELDIANA: ZOOLOGY, VOLUME 46
The Species of the Phyllotis darwini Complex
Four species are recognized. They are so closely related inter
se that if large series from certain crucial areas had not been avail-
able for study, the four might well have been regarded as one.
There is a probability, nevertheless, that even more material from
as yet unexplored regions may reverse this conclusion and prove
that all members of the P. darwini group are still intergrading
segments of a single species.
A key to the species based on morphology alone would not
be feasible, if at all possible. The key devised by Pearson (1958,
pp. 407-408) to all species of the genus Phyllotis depends largely
and, in critical areas, entirely, on geographic data. This is extreme
and prejudices taxonomic judgments. Only the species of the dar-
wini complex lack trenchant diagnostic characters. The members
of the group, however, are mostly or wholly allopatric to each
other. Several occupy parts of a geographic gradient in size and
some differ in proportion of parts and the shape of the baculum.
These considerations are combined in the following "key" to the
species.
1. Phyllotis haggardi. Andes of Ecuador. Size small; tail short-haired, less
than 95 mm. and always shorter than head and body combined.
2. Phyllotis andium. Andes of Ecuador and Peru as far south as Lima.
Average size greater than haggardi; tail short-haired and more than
95 mm. or longer than head and body combined; base of baculum con-
vex or plane (osilae type, fig. 7).
3. Phyllotis darwini. Peru from Junin and Lima departments south into
Bolivia, Chile and Argentina. Average size greater than andium; tail
short- or long-haired and longer or shorter than head and body com-
bined; base of baculum concave or plane (darwini type, fig. 7).
4. Phyllotis osilae. Andes of southern Peru (Cusco-Puno), Bolivia, northern
Argentina; size and proportions as in P. darwini; tail short-haired; ears
usually less than 23 per cent of head and body; m 2 - 3 with first primary
fold obsolete or absent in moderately worn tooth; second primary fold
of m 3 nearly always an enamel island; base of baculum convex or plane
(osilae type, figs. 7, 86).
Phyllotis haggardi Thomas
Phyllotis haggardi Thomas, 1898, Ann. Mag. Nat. Hist., (7), 2: 270. Thomas,
1912, op. cit., (8), 10: 409-410 comparisons. Lonnberg, 1913, Ark. Zool.,
Stockholm, 8, (16): 27 Pichincha (Mt. Pichincha; Quito). Stone, 1914,
Proc. Acad. Nat. Sci. Phila., p. 11 Pichincha (Hacienda Garzon, Mt.
Pichincha, 12,000 ft.). Allen, 1916, Bull. Amer. Mus. Nat. Hist., 35: 120
Pichincha (Mt. Antisana, 12,000 ft.). Pearson, 1958, Univ. California
Publ. Zool., 56: 441 characters; comparisons.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 257
Phyllotis haggardi haggardi, Pearson, 1958, Univ. California Publ. Zool., 56:
442 Imbabura (Mt. Mojanda); Pichincha (Guaillabamba; Imbuyo; Je-
rusaten; La Providencia; Perucho; Puellaro; Puembo; Tanda; Ventanilla;
Quito; Mt. Pichincha); characters; comparisons; distribution.
Hesperomys elegans, Tomes (not Waterhouse), 1860, Proc. Zool. Soc. London,
I860: 213 Chimborazo (Pallatanga).
Phyllotis elegantulus Thomas, 1913, Ann. Mag. Nat. Hist., (8), 11: 139 type
locality Pallatanga, Chimborazo Province, Ecuador.
Phyllotis haggardi elegantulus, Pearson, 1958, Univ. California Publ. Zool., 56:
443 status of type.
Phyllotis fuscus Anthony, 1924, Amer. Mus. Nat. Hist. Novit., no. 114: 1
type locality Contrayerbas, Azuay, Ecuador, 11,000 ft. Goodwin, 1953,
Bull. Amer. Mus. Nat. Hist., 102: 324 history of type; measurements.
Phyllotis haggardi fuscus, Pearson, 1958, Univ. California Publ. Zool., 56: 442
Azuay (Contrayerbas); Chimborazo (Mt. Chimborazo; Urbina); Pichin-
cha ("Galaya" [ = Saloya]; Guamanf; Mt. Antisana; Mt. Corazon, Cota-
pafi (Mt. Illiniza); Napo-Pastaza (Papallacta); characters; comparisons;
distribution.
Type.- -Skin and skull, sex unknown, British Museum (Natural
History) no. 98.5.1.11; collected October 1897, by Ludovic Soder-
strb'm.
Type locality. Mt. Pichincha, above Quito, Pichincha Province,
Ecuador; altitude, 340(MOOO meters.
Distribution (figs. 70-72). Andes of Ecuador, from just north of
the Equator to about 3 30' south in the Province of Azuay; alti-
tudinal range from approximately 2000 to over 4000 meters above
sea level.
External characters. Smallest species of the P. darwini complex;
tail less than 95 millimeters and shorter than combined head and
body length; ears short, apparently less than 23 per cent of com-
bined head and body length; upper parts of body buffy to dark
brown with head and rump not markedly different from back;
under parts gray, well defined from sides, a minute pectoral streak
rarely present; tail bicolor, short-haired, pencil little developed.
Cranial characters (figs. 78, 79). Interorbital region narrow, par-
allel-sided or, usually, concave mesially, the edges square; proximal
ends of nasals usually pointed and terminating behind plane of fronto-
premaxillary sutures; posterolateral palatal fossa well excavated,
the pits large and usually situated anteriad to plane of posterior
border of palate; antero-posterior length of bulla, less tube, sub-
equal to alveolar length of molar row.
Dental characters. Generally as in P. darwini; alveolar length
of molar row, 3.9-5.0 (49 specimens).
258 FIELDIANA: ZOOLOGY, VOLUME 46
Comparisons. Phyllotis andium is the only closely related spe-
cies found in or near the range of P. haggardi. It is distinguished
by longer tail and cranial characters described under the species
heading. Comparisons with other species are made elsewhere (p. 263) .
Variation. Pale and dark populations are scattered throughout
the range of the species. As a rule, dark populations occur at the
altitudinal peaks of the range, i.e., on the high humid grasslands,
or paramos, of Mounts Pichincha, Mojanda, Corazon, Antisana, etc.,
from 3500 meters to more than 4000 meters above sea level. Most
of these dark populations are isolated from each other. Pale popu-
lations are found at the opposite altitudinal extremes, in the iso-
lated arid and semi-arid intermontane valleys, between 200 and
2500 meters above sea level. Dark and pale populations grade in-
sensibly into each other, or into the main population mass occu-
pying the broad and continuous intermediate altitudinal zone.
There is an increase in size and relative length of tail from
north to south. Because of the uneven topography and the great
diversity of local environments, the gradient is correspondingly un-
even, obscured at some points and disrupted at others.
Although recognizing the cline in size, bodily proportions and
color, Pearson (1958, pp. 441-443) admitted three subspecies of
Phyllotis haggardi. The nominate form was restricted to the type
locality in the Pichincha-Quito area, thence northward about 30
miles to Mt. Mojanda. P. k. elegantulus was recorded from its
type locality only in Pallatanga, Chimborazo, while the range of
fuscus engulfed those of the other two. A specimen in Chicago
Natural History Museum from Saloya, misspelled "Galaya" on the
museum label, was referred by Pearson to fuscus on the assumption
it originated in the province of Chimborazo. Actually, Saloya lies
west of Mt. Pichincha in Pichincha province. The Saloya speci-
men was taken by F. Mena. Two specimens from Chimborazo, in
Chicago Natural History Museum, were also collected by A. Mena.
Taxonomy. Phyllotis haggardi was originally characterized as
"The Ecuadorean [sic] representative of the Chilian Ph. darwini
. . . distinguished by its smaller size and smaller ears." Present
material confirms the smaller size of haggardi. Collectors' ear meas-
urements are not available for the vast majority of the specimens
examined. The ears, however, do appear to average smaller in
proportion to head and body length than those of most members
of the group. The type, collected by Soderstrom, is an imperfect
specimen with incomplete skull and without the usual collector's
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 259
data. Its published external measurements were taken from the
dry skin. Specimens at hand include 79 individuals from the type
region, also collected by Soderstrb'm. Most of them are juvenals
and subadults. The color and texture of many skins indicate undue
exposure to drying and fading. No external measurements are given
and accurate ones cannot be made on the distorted specimens.
There is considerable mismatching between skins and skulls of the
same species while some skins are coupled with skulls of mice of
the genera Akodon, Thomasomys and Reithrodontomys. It is assumed
that data given on the original labels of some of these Sb'derstrom
specimens are likewise untrustworthy.
Phyllotis elegantulus Thomas, from Pallatanga, Chimborazo Prov-
ince, was described as "a small species allied to Ph. amicus, but with
shorter tail." The type was skinned out of spirits and the original
description is based on the dried, made-up skin. Color of the type,
said to be "somewhat modified . . . but apparently as in Ph. amicus,"
agrees as well with that of Phyllotis haggardi. External measure-
ments and cranial characters given by Thomas for distinguishing
elegantulus from amicus are precisely those that distinguish haggardi
from amicus. Present material from the type region of elegantulus
is unquestionably representative of haggardi. Pearson (1958, p. 443),
who examined the type and what appeared to be a topotype, con-
firmed the identification of elegantulus with the nominate form of
haggardi rather than with fuscus. He, nevertheless, retained ele-
gantulus as a valid subspecies, chiefly to avoid placing the "clearly
defined P. h. fuscus into synonymy under the almost unknown
elegantulus."
Phyllotis fuscus Anthony, from Contrayerbas, Azuay Province,
Ecuador, was distinguished from topotypes of haggardi by darker
color and longer rostrum. The Contrayerbas series at hand does
average darker than Mt. Pichincha and Quito haggardi, but the
difference is local, if not seasonal. A large series of Phyllotis from
Mt. Antisana just southeast of Quito also averages darker than
topotypes of haggardi and is quite as dark as the Contrayerbas
Phyllotis. The longer rostrum attributed to fuscus as compared
with topotypes of haggardi merely reflects the increase in size of
the species from north to south. The proportions of the parts,
however, remain practically the same, as shown in Table 11. Speci-
mens listed are those of fully mature adults with skulls in good
condition.
260 FIELDIANA: ZOOLOGY, VOLUME 46
TABLE 11. Measurements of topotypes (Mt. Pichincha) of Phyllotis haggardi
Thomas and topotypes (Contrayerbas) of Phyllotis fuscus Anthony
Greatest
length Nasal Ratio
Locality Specimen no. of skull length %
Mt. Pichincha 1 CNHM 53305 26.5 11.7 44
MACN 31150 26.7 11.3 42
31151 25.7 11.3 44
AMNH 46825 26.6 10.8 40
46826 26.2 10.5 40
46829 26.5 11.3 43
46836 27.0 11.6 43
Contrayerbas 2 AMNH 62050 3 29.5 12.6 43
61957 29.0 12.3 42
61959 28.7 12.4 43
61960 28.3 11.5 40
61961 28.7 11.0 38
1 Means and extremes of nasal length of 11 specimens measured by Pearson
(1958, p. 465), 10.930.14 (10.4-11.7).
- Means and extremes of nasal length of 5 specimens measured by Pearson
(1958, p. 465) 12.340.12 (12.0-12.6). The difference of 1 millimeter in the mini-
mum length of the nasals in the two sets of measurements does not affect the con-
clusions. If nasals of no. 61961 were 12.0, the ratio would be 42%.
3 Type of Phyllotis fuscus Anthony; measurements from original description.
Measurements. See Table 12.
Specimens examined. 124, all from Ecuador. Pichincha: Mt.
Pichincha and vicinity including Quito, 49 (AMNH, 40; CNHM, 4;
MACN, 2; MCZ, 3); Mt. Mojanda, 12 (AMNH); south slope of
Mt. Mojanda and vicinity of Guaillabamba, 7 (AMNH); Rio
Guaillabamba, 1 (AMNH); Jerusalem, Guaillabamba, 4 (AMNH);
Puellaro, 6 (AMNH); Puembo, 1 (AMNH); Jiron, 1 (AMNH);
Saloya, 1 (CNHM); Mt. Antisana, 16 (AMNH, 13; MCZ, 3); Mt.
Corazon, 12 (AMNH). Cotapaxi (formerly Leon): Mt. Illiniza,
1 (MCZ). Napo-Pastaza: Papallacta, 1 (AMNH). Chimborazo:
Urbina, 1 (AMNH); Mt. Chimborazo, 3 (CNHM). Azuay: Contra-
yerbas, 8 (AMNH).
Phyllotis andium Thomas
Phyllotis andium Thomas, 1912, Ann. Mag. Nat. Hist., (8), 10: 409. Osgood,
1914, Field Mus. Nat. Hist., Zool. Ser., 10: 165 Cajamarca (Hacienda
Limon near Balsas; Hacienda Llagueda); Libertad (mountains near Otuz-
co). Thomas, 1926, Ann. Mag. Nat. Hist., (9), 18: 162 Amazonas
(Condechaca; Chachapoyas; Molinopamba). Thomas and St. Leger,
1926, op. cit., (9), 18: 348 Amazonas (Goncha). Pearson, 1958, Univ.
California Publ. Zool., 56: 408, 440 characters; comparisons; distribu-
tion [for locality records see explanation of figs. 71, 72]; synonyms, me-
lanius, stenops, tamborum, fruticicolus.
A
^
0)
I_
- *
O o
01
CM t-
o
Q.
"3
j= *"
t
lO
_>>
i
_>
*J u-
bcja
co
cg c<T co"
?
"
^
-1 w*
i. 5
Tf > I Tj< ?O T
f o co o"
;|
*c
c
1 1
<u
f-
10
E
u
O
oT
c
<D
1*
O <j;
ICOCO I ** I ^l 1 ^1* "5 liO^
o
r
-^ 10 co
t-' t- oi oo'
CM eg CM eg
K
-i
C-1CMCMCMCMCM
C
'5
;s>
E
ri C
-
C
2
lO O
t- O -H
OS r-l -H
c> . to co co
O ^H O CM r* ~*
>- OS 1 I OS f-H '-I
2
s. E -
i'rtrt
- -
3 1 1 1 S- 8
5 E
<s> V
s _ ~
261
262 FIELDIANA: ZOOLOGY, VOLUME 46
P[hyllotis] andium, Thomas, 1926, Ann. Mag. Nat. Hist., (9), 17: 615 Ama-
zonas (Chachapoyas); stenops a synonym.
[Phyllotis lutescens] andium, Osgood, 1944, Field Mus. Nat. Hist., Zool. Ser.,
29: 194 classification.
Phyllotis melanius Thomas, 1913, Ann. Mag. Nat. Hist., (8), 11: 407 part,
skull only; ECUADOR: (type locality Porvenir, Bolivar, 1800 meters).
Pearson, 1958, Univ. California Publ. Zool., 56: 440 type a composite of
skull of Phyllotis andium from Canar and skin of Akodon aerosus from
Porvenir; type restricted to skull only.
Phyllotis andium stenops Osgood, 1914, Field Mus. Nat. Hist., Zool. Ser., 10:
165 PERU: (type locality Rio Utcubamba, 15 miles above Chacha-
poyas, Amazonas, altitude, 7500 feet).
Phyllotis tamborum Osgood, 1914, Field Mus. Nat. Hist., Zool. Ser., 10: 165
PERU: (type locality Tambo Carrizal, east of Balsas, Amazonas).
Phyllotis andium tamborum, Thomas, 1926, Ann. Mag. Nat. Hist., (9), 17:
614 PERU: Cajamarca (Celendin); Amazonas (Tambo Carrizal; Leima-
bamba).
Phyllotis fruticicolus Anthony, 1922, Amer. Mus. Nat. Hist., Novit., no. 32:
1 ECUADOR: (type locality Guachanama, Loja, Ecuador, 9050 ft.).
Goodwin, 1953, Bull. Amer. Mus. Nat. Hist., 102: 323 history of type;
measurements.
Phyllotis daricini posticalis, Thomas (not Thomas), 1927, Ann. Mag. Nat.
Hist., (9), 20: 602 -PERU: Hudnuco (Llata); Pasco (Huariaca); Ancash
(Pira).
Type. Adult male, skin and skull, British Museum (Natural
History) no. 99.9.9.68; collected 18 April, 1899, by Perry O. Simons.
Type locality. Canar, Canar Province, Ecuador; altitude, 2600
meters.
Distribution (figs. 70-72). From Tungurahua Province in the
Andes of central Ecuador south through the Andean departments of
Peru between the coastal and Rio Huallaga drainage basins as far as
northern Junin and western Lima; altitudinal range from approxi-
mately 200 to 4800 meters above sea level.
External characters. Average size larger than P. haggardi, smaller
than P. darwini; tail 95 millimeters or longer and usually (always
in Ecuador) longer than combined head and body length; ear, from
notch, 25 millimeters or less; upper parts nearly uniformly warm
brown; sometimes buffy or slightly grizzled but with little or no con-
trast between anterior third and posterior parts of body; underparts
gray, often with a thin wash of pale buff; a poorly defined pectoral
patch or streak rarely present; tail short-haired with poorly developed
pencil, sharply bicolor but tip often uniformly brown.
Cranial characters. Interorbital region parallel-sided, or, usually,
concave mesially, the edges square, never beaded or forming ledges,
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 1>63
the median frontal sulcus weakly defined or absent; proximal ends
of nasals usually truncate and terminating approximately in line
with fronto-premaxillary sutures; posterolateral palatal fossa poorly
defined, the pit (or pits) large or small and situated on a line with,
or, usually, anteriad to, plane of posterior border of palate; posterior
border of palate round or square and with or without median cleft
or median process; width of mesopterygoid fossa, measured at base
of hamular processes subequal to or less than width of parapterygoid
fossa measured at same plane, sides parallel or slightly concave
medially, sometimes slightly divergent; bullae moderately inflated,
antero-posterior length, less tubes, 3.8-4.8 and always less than
alveolar length of molar row; auditory bullae comparatively little
inflated, Eustachian tubes short to moderately elongate.
Dental characters. Generally as in the P. darwini group but
m 1 more often S-shaped than 8-shaped, pf 1 of m^ more often ab-
sent or obsolete in moderately worn tooth, pf 2 of nv 1 nearly always
an enamel island; molar rows parallel or slightly convergent pos-
teriorly; alveolar length 4.1-5.3 (190 specimens).
Baculum. See discussion on p. 58 and figures 7 and 8.
Comparisons. Two species and three subspecies of the Phyllotis
darwini complex occur in or near the range of P. andium. The
Ecuadorian P. haggardi is slightly smaller with tail actually and
proportionately shorter. P. darwini posticalis and P. d. limatus
average larger throughout with bullae usually more inflated. P. d.
definitus is absolutely larger with molars larger, body more warmly
colored throughout, the under parts washed with ochraceous, pectoral
patch well defined.
Separation of Phyllotis andium from P. haggardi and P. darwini
posticalis is not always clear. Evidently, speciation was recently
accomplished and only in critical geographic areas is it sufficiently
defined for recognition. Specific distinction between P. andium and
P. darwini posticalis is predicated principally if not solely, on the
basis of a small series of each species collected by Pearson near
Casapalca, Lima, Peru. Here the representatives of the two species
differ in virtually all dimensions, notably in inflation of bullae and
proportional width of interorbital region (Table 13). Some of these
differences may be age factors, the andium series being younger.
The posticalis series, however, is also darker, more gray, with a
coarser ticking, has more prominent guard hairs, hairier tail and
its median palatal spine is poorly defined or absent.
% t:
auids IB^BIBJ 02 = = =
u -O
O. rt
q^3uai ||ti3js t^ t^ oo oo t^~ oo oo oo
:MOJ JBjoaAiv
2
o>
(X
t^ oo o ci ^o t> ^ ~^
rt
A\OJ JBJO3AIV ^' Tt W3 Tf 10 10 10* IO*
J
qi3U't| oooo -H^HOOO
3
Itn>js :SIBSBM
1
oo o co Oi TJ< o
A
SIBSBN 2 ^ S 2 2 S ^ S
o
o
i
aBjjnq XJQ^. 0303^0-^ oqi-noiOi
2
-ipnB jo q^Sua^j ^ "*' "* ^
1
"w
q^Suaj {(nj^s ^on^o rj<^<ioio
i
: jB^iqjoja^uj
&,'
TllStl^I ^^ ^"" ^^ ^^ ^^ ^^ ^^
"O
t t t-t cg'-HOoo" o
TTHMS isaiBaj-O eg eg eg eg 03 03 co eg ^
g
CO
S
1
Q
Xpoq oooeg oocg-^J* Z
egegcg'vj ^jegcgcg o
PUB pBaq :JBg
.
0)
",5
._._, OOOrH Tj<lOeDTj< K*
^o
J ' { eg eg eg eg eg eg eg eg . ;
"s>
o
S
"o
(Aip) ;ooj pui H SSScg e^So3e5 1
s
$
eg-^oso t-co-^to c
^IB^ i i i it i T-> Mcgo"
t,
o>
03
Jjj
OOiOOt^ H tO tO H S
Apoq PUB psajj oosoicft egcgr-io ^
|
^H ^H ^H ^H ^H QQ
*o
CO
1t
fe
3
5J "i
n
^^
^
j 5 *5
t"*
03 03 o: -^^ 03 .^ ^
^4
^.J" o > i eg co 10 o t- oo o-
*^ ^H^-,^H^I oooooooo -3 a
O oooo oooo =S
j oooo oooo "S't;
c
0)
^gcgcgegeg-gcgcgegcg % %
.E,
(^ S *^
1 1 ss ^ I s s *
o
264
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 265
Specimens of darwini and andium from other localities in the area
of sympatry are imperfect for comparative purposes. One specimen
of Phyllotis darwini limatus (MVZ 120033) from Surco, Lima, is a
hydrocephalous Juvenal with an abnormally inflated braincase (fig.
80,a). Its skull cannot be fairly compared with those of three adult
andium from the same locality. However, external differences be-
tween the Surco darwini and sympatric andium are the same as ob-
tain between the two Casapalca species except that the tail of dar-
wini is not appreciably longer-haired. One specimen of P. darwini
limatus from 1 mile east of San Bartolom is also pale, with a more
coarsely ticked coat and slightly hairier tail as compared with a series
of 10 specimens of andium from the same locality. The andium
series also shows well the shorter and broader muzzle, less inflated
bullae and other distinguishing cranial characters of the species.
Some allopatric series of andium, notably one from Chongoyape,
Lambayeque, differ even more widely from the sympatric series
of posticalis while others overlap in all characters except relative
degree of inflation of the bullae. The slight but real difference
in the auditory bullae is fairly constant throughout the geographic
range of both species. Unfortunately bullae cannot be accurately
compared in terms of the linear measurements used here.
Evidence of sympatry between P. andium and P. haggardi is lack-
ing. Both species become larger, their tails longer, from north to south.
The size cline in andium begins along the same coordinate south
of the point where the known range of haggardi ends. On the other
hand, P. andium remains nearly the same size with the same long
tail where its range parallels that of P. haggardi. This phenomenon
is the dubious basis for specific separation of the two forms. Cranial
characters used by Pearson (1958, p. 437) for distinguishing haggardi
from andium include "longer palate, posteropalatal pits usually sunk
in depressions, tooth rows tending to converge posteriorly, zygomatic
arches more widely flaring." These characters though valid in present
material are of the kind which in larger samplings usually prove
to be local or individual variables.
The less nearly related Phyllotis amicus is smaller, with longer
tail, larger ears, skull with broad divergent-sided supraorbital region,
incisors more delicate and m^ with procingulum more developed.
Variation. The various series of andium from the Department
of Lima are fairly uniform in cranial characters, notably in the
presence of a well-developed median spine on the posterior border
of the palate. This feature is insignificant or absent in the vast
266 FIELDIANA: ZOOLOGY, VOLUME 46
majority of andium from elsewhere. Specimens from localities in
Lima coincident with or near the range of dark-colored Phyllotis
darwini posticalis are dark, others from paler Phyllotis darwini
limatus territory (Surco, Santa Eulalia) are correspondingly paler.
A series of 36 specimens from Macate, northern Ancash, taken
from 1 February through 6 March, 1914, by M. P. Anderson,
is more brown, on an average, than andium from the Department
of Lima. A series from Yungay, Ancash, collected March 4-6,
1954, southeast of Macate, is more somberly colored because all
11 specimens are in old, worn pelage. Nevertheless, patches of
new pelage on the dorsum of one specimen (CNHM 81246) are
colored as in the Macate series. Thirty-three specimens from
Huaras, Quilcayhuanca and Hacienda Catac, in the Department
of Ancash, are paler than those from Yungay. They were taken
in February 1954. All are in old pelage, but some show patches
of new pelage. None compare with the Macate specimens which
are in prime pelage although taken in the same general region
during the same month 40 years earlier. The series from Huaras
includes individuals nearly as pale as coastal Phyllotis darwini limatus.
Eight small, pale, long-tailed mice from Chongoyape, Lamba-
yeque, a locality 240 meters above sea level on the coast of northern
Peru, closely resemble large individuals of the nearly related Phyllotis
amicus. This population may represent a desert race characterized
by small size, extremely pale color and long tail. In most of the
Chongoyape specimens the molar crowns are considerably worn,
the dentine deeply excavated. As noted elsewhere, unusually small
size appears to be correlated with excessive molar wear. Evidently,
in the Chongoyape ambience the mice were obliged to feed on tough-
fibered plants with low nutritional value.
Taxonomy. The type of Phyllotis andium stenops Osgood, from
Rio Utcubamba, Chachapoyas, is the only fully mature individual
of a series of ten from the Chachapoyas area in southern Amazonas.
The series was distinguished from Cajamarca representatives of
andium "principally by the narrowness of [the] nasals." It has
already been shown by Thomas and Pearson that subspecific dis-
tinction of stenops by this or any other character is untenable.
The type of Phyllotis tamborum Osgood, from the mountains
east of Balsas, southeast of Chachapoyas, is a juvenal absolutely
indistinguishable from Chachapoyas stenops.
Phyllotis fruticicolus Anthony, from Guachanama, southern Ecua-
dor, is, as shown by Pearson (1958, p. 441), indistinguishable from
X
CO
X
5?
<J"I
oq C3 os to to os eg TO cs os as t~-. o oo
T}< 1C * -rjl -rj* -rf U3 IO U3 rf -r. ' Tjl 10
a
i
e
1/3 rH _
<1 O to
W3 U3 U3 to IO
L I L I V
10 rH to u3 eg
eg' TC'
**
Tf
TO
^ ^f TO O OS 1C
rH
rH* 00
t^"
Sjj
O U3
e
t- to
|
oo
^
t~ Os 1C
w
rU 00
to
^
c eg eg
cr.
T}< TO
t-
CO
oo
eg
i
TO
Os OS O
eg eg TO
i i I
TO eg TO
?i
CO
2S
si, S
oo
eg
ac
e5
t- t~ 00
eg eg eg
?]
t-' to'
eg eg
X
O4
t^ to eg w rH -*j<
o to
71
o eg o T
c rf os oo
eg os
CO
/ to to co oo os
t~- 1C
oo oo os o
> oo t- oo
s
oo c~
1 -
W
oo
c7
OJ
eg^ eg_ eg .1,
10 TO us eg^
OO OS rH 1C rH ,_, OO
S" P P oo" oo" P~ oo~
eg eg eg eg eg eg M
i 1 l ' i 1
Tf kOrl<tOCOu3U3ic
e^j 10 us eg eg eg e-i e>j eg e>i
t~ c- to to to"
o M
O O OS
rH rH OS
TJ 00 TO 00 CO TO
rH eg eg eg eg eg eg
Cg rH rH rH rH rH rH
1-1 III I I
00 it tO O t~ OS
co oornoooeg
OO"~lrH OOrHt-tOOSt COT*""!
rHegrHOOCgTOrHrHrHOrHrHOO
rH OS rH OS rH rH rH rH rH rH _ rH OS
ECUADOR
Punfn 88,
Canar 1 Hi
Yunguilla
Valley 90,
Guachanama 2 91
Guachanamd 84
OO
^
1
o
eg
l
?i
T!
1
rH eg
rH rH
1 1
t eg
1
00
=.
to
to
~
o
- 1
S
t^ eg
rH O
2 S
N
t-
el
i -
oT
O Os
'
jg
w t
TO if
/
-
00 "3
frt "*1*
S
rH OS
*
rt
~
Tn
01
Chongoyape
Cabache
^
9
Chachapoya
Chachapoya
Carrizal 6
-
\
~
c
a
CO
Cajamarca
Limon
near Otuzco
Llagueda
Macated" cf
-
-
1
od
-
-
^
Yungay
Huaras
Quilcayhuar
Catac
Cullcui
267
1.2
os co
co eg
d
o
o
c
as
aS
o>
(-<
73
C
73
aS
0)
c
73
IV
C
T3
OS
0)
o
o
<l|
eg" of c
<s o eg" o co"
~
-i:
.1:
.1:
CD
u
O CO
id *'
t- os
c
c
^
. II
J3
"bo
o>
JS
"be
O)
^:
M
(V
E- 1
.c
"Si
O
1 1
II
c ~a
of eg"
oo CD oc ^_
!. ^3
__
o
11
TJ- T}-
CO T).' CO Tf
t-
G
) "O
3
"3
"as
"c3
oc* -^ c
> ^f CD -5j< CO
4 C
OS
cr
o>
7
cr
0)
cr
c
S3
TT T} if
5 -n- -5t rf. ^j.
d
CC
a
> ,
H-,
as
(continued)
CO
0)
CO CO
d os
06" oc"
t- os
co eg
t~ TJ" OO -^f
o
eg
i
o
>
^
c
JS
1
l "^
' r'i
i
O
eg
"be
o
73
c
JS
bo
o
eg
-a
c
bo
o
c
bo
1
'3
02
a
o
~ c
os oc
> ' i<T co Tt"
II
a
' C
1 Q)
C
C
"bo
g
,s
s
Q
OS t- CT
eg eg o<
> 00 OC OO OC
i eg s ] eg eg
t- os
T3
O
.0
73
.2 "2
_c
5
J2
T3
C
C
T3
C
o
aj
-s
as
~
73
i eg
"l "l
-*-* QJ
1
rt?
M
Co
OS
as
X
ca
K
L ! "H
o ;
_aj
O)
f
S
JS
0)
(D
X
as
*3s
eg eg eg
eg eg eg eg
_>
"2
c
-c
o>
c
do
c
1
OJ
JC
.>
o
_c
IS
IS
IS
IS
o>
*c
K
i2
<U
-s
c
CD" us"
eg_ eg^
CD CD
eg eg
l
"3 CD -^ CO
eg^ eg_ eg^ eg
1 .fi-
ll 1
CJ
as
"H
8
c
CJ
C
CJ
c
8
S
c
com bin
<D
eg eg eg
CO CD U3 CD
eg eg eg eg
31 ^
!J|
J
j:
"^
5
"5
4J
c
OJ
3
*? o
Q
i_
iU
5
fl)
W
i
t~ OS
C ~*^ "-j
Q)
c
Q)
2
U
t-.
u
O
o
o
%
co eg
oc oc
bC o; C
S ^
IS
JS
T.
T.
JT
a:
1
i i ^*
> ~' CJ ^i
eg
X
if5
M
*M
eg *?*
t"~ ^* os - ~
***
^ '
CC
Q
i
,
f
2
H
eg *
o -H o eg
3 O)
1 5
"S
.
c
c
C
a
cc
t~T CD" o
-* o ~
os "5 o CD"
~ ^ eg eg
M 0) "Cj
y C Q)
c "1
) ^s -^
_3 *^
~" tT
bo
C
bo
c
tT
bo
C
fe
bo
O)
be
c
*c
o>
bo
H
73
t^
t^ os
||
u -C u
s" c
2 -2
^
2
3C
2
c^
c
-0
o
00
eg ^
"1
CD "~
t^^ ^5 ^5* 1^5
1^11
E l?|
X
O "o
S u
Ij
5
=1
DC
'S
1
l
o>
a
*-T "1 eg
* OC -H
T O TJ< ~"1
o ^ o os
i -I ,
s -^ ~
S CJ
ij
s -g
=c
C "r-r
DO
o
go
a:
is
oc
01 o
go
oc
Jo
" oc
DC t
!<= j
5 ^.
-2
"S
'? *"
QJ s^.
<X.
. c
a
*o "c *c *o
"o "3
a "^
i-2
Q.^
Is
a'*
a -^
c
5 "
O C^ ar G;
O> oc
gQ
o "^
< T
^ T
__, "T 1
32 -^
"as
|{j
1 1 5 1
a a r= Q.
>> > rt >>
f_ EH H H
a :=
>j as
E- 1 E- 1
^ ^
c^
cE
cE
cS-
-HCD
C 8?
CJ
II s
S E
= C 2 u
o =
r- .
c. II
73
2 ^
-a
'_' II
T3
"C
o
o
O
O
JO
.0
^2
268
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 269
andium. The description was based on a comparison of the type,
an immature male, and two immature topotypes with Phyllotis
haggardi.
According to Pearson (1958, p. 440) the name Phyllotis melanius
Thomas, 1913, is based on a skin of an Akodon aerosus and a skull
of a Phyllotis andium. Skin and skull were collected by P. O. Simons,
the former in Porvenir, Bolivar, Ecuador. Both bear Simons' field
number 258 and the British Museum (Natural History) number
99.9.9.107. Pearson restricted the name Phyllotis melanius to the
skull alone. He further demonstrated that a skin only of Phyllotis
andium, also collected by P. 0. Simons and with the same field
number, was almost certainly the correct skin of the type skull.
Inasmuch as Phyllotis does not occur in Porvenir, Ecuador, and the
skin with the same field number as the type skull originated in
Cafiar, Ecuador, the type locality of melanius was redetermined
as Canar by Pearson. Phyllotis melanius thus becomes a topotype
and absolute synonym of P. andium.
Measurements. See Table 14.
Specimens examined. 212. ECUADOR. Chimborazo: Punin,
Quebrada Chalan, 4 (AMNH). Azuay: Pauijchi, 1 (AMNH); Yun-
guilla Valley, 7 (CNHM). Loja: Guachanama, 2 including type of
fruticicolus (AMNH). PERU. Piura: Ayavaca, 1 (CNHM); Huan-
cabamba, 5 (AMNH, 3; CNHM, 2). Lambayeque: Chongoyape,
8 (CNHM); Cabache, 1 (CNHM). Amazonas: Chachapoyas, 13
including type of stenops (CNHM, 10; AMNH, 3); San Pedro,
south of Chachapoyas, 6 (CNHM); Tambo Carrizal, the type of
tamborum (CNHM). Cajamarca, 10 (AMNH, 1; CNHM, 9); Haci-
enda Limon, 2 (CNHM). La Libertad: Hacienda Llagueda, 2
(CNHM); mountains near Otuzco, 2 (CNHM). Ancash: Macate,
41 (AMNH, 2; CNHM, 36; USNM, 3); Yungay, 11 (CNHM);
Huaras, 14 (CNHM); Quebrada Quilcayhuanca, Huaras, 11
(CNHM); Hacienda Catac, Ticapampa, 8 (CNHM). Huanuco:
Cullcui, 3 (CNHM); Ambo, 10 (AMNH, 1; CNHM, 8; USNM, 1).
Lima: Matucana, 7 (CNHM, 3; MVZ, 4); Surco, 3 (CNHM, 1;
MVZ, 2); Casapalca, 4 (MVZ); Canta, 1 mile west, 2 (MVZ);
Huaros, 8 (MVZ); San Mateo, 6 (MVZ); Villavista, 8 (MVZ);
Zarate, 10 (MVZ); San Bartolome" Station, 1 (MVZ).
Phyllotis darwini Waterhouse. (Synonymy under the species and
subspecies.)
Distribution (figs. 57, 70). From the departments of Junin, cen-
tral Peru, south along the Pacific coast and highlands through Peru,
270 FIELD IANA: ZOOLOGY, VOLUME 46
Chile, Bolivia and Argentina to the Straits of Magellan, and east to
the Atlantic coast in the Argentine departments of Santa Cruz and
Comodoro Rivadavia; altitudinal range from sea level to 5000 meters
above or to snow line.
Characters. External, cranial and dental characters are those
of the P. darwini group; base of baculum convex or nearly plane
as described elsewhere (p. 58, figs. 5-8).
Comparisons. Phyllotis darwini figures in comparisons made be-
tween members of the darwini complex, with other species of the
genus Phyllotis (p. 236) and with phyllotines in general. The geo-
graphic relationship between P. darwini and other members of the
complex is discussed under the heading Sympatry and Allopatry
(p. 31). Differences between P. darwini and sympatric representa-
tives of P. osilae are shown in Tables 30-49, and pp. 346-357. The
differences are idealized in figure 86. Comparisons between P. dar-
wini and sympatric series of P. andium are made in the account of
the latter.
Variation. GEOGRAPHIC: The ten subspecies of P. darwini rec-
ognized here are, from north to south, definitus, posticalis, limatus,
rupestris, magister, wolffsohni, caprinus, darwini, fulvescens and xan-
thopygus. The palest race, Phyllotis darwini rupestris and P. d.
limatus live in the driest parts of the range of the species; the most
saturate race, fulvescens, inhabits areas of high rainfall. The finely
graduated increase in humidity along the Pacific Coast from southern
Peru to southern Chile is correlated with a correspondingly fine
transition from limatus and rupestris, through more intensely col-
ored darwini, to saturate fulvescens. The boundaries of the ranges
of most subspecies conform closely to the hyetal lines which de-
marcate the principal zones of rainfall. There is no such correla-
tion between altitude per se and color or any other subspecific
character.
A size gradient between subspecies is not apparent. P. d.
rupestris averages smallest but intergrades directly or indirectly with
all other races. P. d. rupestris becomes larger from western Peru
and Chile eastward into the high Andes but without significant
differentiation in proportions or other characters. This even gradient
is no basis for divisions into the two or more subspecies (chilensis,
vaccarum, ricardulus*) recognized by other authors. On the other
hand where the change in size is abrupt as in the case of rupestris
and magister no cline is evident but two sharply defined taxons are.
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 271
Tail length averages slightly less than combined head and body
length in present samples of rupestris, darwini and xanthopygus,
slightly more than head and body length in posticalis, wolffsohni
and magister, considerably more in limatus (118:100), and most
in caprinus (122:100). It is significant, however, that practically
the full specific range of variation of tail length relative to head
and body length obtains in such races as P. d. posticalis (72 137:100)
and rupestris (81-132:100). More specimens of these than of other
races were examined.
The principal obliquity in cranial characters is the strongly
divergent-sided supraorbital region in most specimens of wolffsohni.
The same race is also noteworthy for the consistent S-shaped pat-
tern of its second molars and, to a slightly lesser extent, of its third
upper molars. Phyllotis darwini caprinus bridges the gap between
wolffsohni and other races of darwini (figs. 82-84).
LOCAL: Size differences between two neighboring micropopu-
lations, or pocket populations, of a subspecies may be greater than
the average size difference between two neighboring subspecies. The
tail may average considerably longer than combined head and body
length in some local concentrations of individuals and considerably
shorter in others. For example, in the 5 specimens of P. darwini
posticalis from San Jenaro, Santa Inez, Huancavelica, the ratio of
the tail to head and body is 83, 85, 86, 86, 86, respectively; in the
4 specimens of posticalis from Urco, Cusco, the tail ratio is 117, 121,
126, 136, respectively. A group of individuals inhabiting a com-
paratively humid pocket of an otherwise generally dry region may
be slightly darker than average in coloration. Pelage of populations
inhabiting warm coastal areas may be shorter, thinner, and coarser
in texture than that of populations of the same race living near
the border of perpetual snow. Local differences in the chemical
composition of solubles in drinking water may cause striking local
differences in bulk and density of cheek teeth. These and similar
gross deviations from the overall racial pattern may be impressive
when subjected to statistical analysis. For the most part, however,
they are reflections of age, crop and random genetic variations.
INDIVIDUAL AND AGE: The classical concept of the existence
of a direct relationship between the age of an individual and its
size, pelage, and dental conditions can be applied with some degree
of confidence only to individuals of the same crop. It cannot be
applied generally to phyllotine rodents or, for that matter, to any
mammal without qualifications which are frequently nullifying. Pel-
X
T)
C
a
cd
I
Q
272
_
-
(V
273
8
BE
_ "H
| -i
5
- i
'. 3
0) -
<D O
o ,
274
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS 275
FIG. 81. Left lower molar of Phyllotis darwini: a, unworn; b, moderately
worn; c, well worn.
ages of independently active juvenals and older individuals are,
as a rule, practically indistinguishable. The last molar of independ-
ently active juvenals is as fully developed and functional and may
even be as worn as in adults (figs. 81, 82). Dry season generations or
crops of mice may be smaller individually and collectively and even
paler, than their rainy season counterparts. Molars of dry season
crops of mice may show considerably more abrasion than those of an
older, rainy season crop. Change of pelage, or molt, among adults
is individually variable. Dominance of one pelage phase over an-
other may be suspected in a given series, or for a given season,
but all adults of a population do not undergo the same stages of
molt at the same time. Extraordinary differences in size, condition
of pelage and molar attrition may exist among individuals reared
in highly specialized or artificial habitats and their contemporaries
occupying the natural habitats of the same region.
SEXUAL: In all series with a goodly number of adults of both
sexes, males average slightly larger than females.
Habits and habitat. Phyllotis darwini is the ubiquitous cricetine
of the southern Andean countries. This terrestrial and scansorial
rodent abounds in deserts, scrublands and temperate zone grass-
276 FIELDIANA: ZOOLOGY, VOLUME 46
lands, but appears to be scarce, if not merely an occasionally in-
trusive element, in primary forest. Erstwhile wooded areas of Peru,
Bolivia and Argentina had already been cleared by man in localities
where specimens of P. darwini were collected. On the other hand,
the type of P. d. fulvescens was discovered in the Araucaria forest
of the Cordillera de Nahuelbuta, southern Chile. When describing
fulvescens, Osgood (1943, p. 204) remarked that "in a week's in-
tensive collecting, with three lines of traps out, only the single
specimen (the type) was obtained and this not in a mouse trap, but
in a steel trap set at the burrow of Aconaemys." About the same time,
H. E. Anthony secured another specimen, farther north in the same
region. The Araucaria forest is abundantly gladed and cannot be
more than an ineffective barrier to savanna animals. Except for the
tiny marsupial Marmosa pusilla, this region, like all Chile, has no
arboreal mammalian fauna. According to Darwin (in Waterhouse,
1839, p. 65) the species bearing his name "inhabits dry stony places,"
in the vicinity of Coquimbo, Chile. On the other hand, the original
specimens of P. d. xanthopygus taken by Darwin (op. cit., p. 64)
are "extremely abundant in the coarse grass and thickets in the
ravines at Port Desire and Santa Cruz" in southeastern Argentina.
Emilio Budin (in Thomas, 1919b, p. 200) secured specimens of
xanthopygus "among the cactus plants" in western Argentina.
Pearson (1951, pp. 142, 144) described P. darwini of the Peruvian
altiplano as "a mouse of rocky places. Boulders, rock slides, cliffs,
small shale outcroppings, stone walls, and stone huts are all satisfac-
tory habitations. . . . All the specimens were caught at night, many of
them in the first hour of darkness. Several wild caught individuals
had green vegetable pulp in their stomachs, but a caged specimen ate
assorted grains and ignored the tola bush (Senecio adehophylloides)
which its cagemate, a Punomys, relished." Regarding sympatry with
Phyllotis osilae, Pearson (1958, p. 399) observed that "the two species
may be taken on the same trap line, but the osilae are usually among
the bunch grass locally called ichu (usually Stipa ichu) and the dar-
wini in more open rocky places near by. The same habitat prefer-
ences extend from southern Peru south at least to Jujuy in northern
Argentina, which is as far south as I have collected, and the sympatry
exists between several subspecies pairs: [Phyllotis] osilae osilae and
[P.] darwini posticalis near Cuzco, osilae phaeus and darwini posli-
calis near Limbani in southern Peru, osilae osilae and darwini chilensis
[=rupestris] in the Titicaca Basin, osilae osilae and darwini rupestris
in Bolivia, and osilae tucumanus and darwini ricardulus in Catamarca
HERSHKOVITZ: NEOTROPICAL CRICETINE RODENTS U77
.... Dr. Karl Koford states in his field notes that 5 osilae taken
above Limbani were trapped in thick grass, and that most of the
18 darwini that he collected there were trapped in rocky areas."
Refuge and nesting site of the leaf-eared mouse may be in a
burrow of its own or in that of another animal. The Argentine
collector, Budin (in Thomas, 1926b, p. 604), caught specimens of
Phyllotis darwini and Cavia sp. in traps set at the mouth of cavy
burrows, and believes the two rodents live together. The Chilean
naturalist, John Wolffsohn, addressed a letter to Oldfield Thomas
(1927, p. 556) with the statement that he found Phyllotis darwini
in the same holes with Octodon degus, 0. bridgesi, Abroconia bennetti,
Akodon olivaceus, Abrothrix longipilis, Oryzomys longicaudatus, Rattns
raitus, and Marmosa elegans. This unprejudiced rodent also makes
itself at home in man's dwellings and other structures where (fide
Mann, 1945, p. 40) it competes successfully with the Old World
house rat, Rattus rattus}.
Accounts of ratadas, or periodic concentrations of great numbers
of mice in localized areas where certain foods are available, do
not refer specifically to any Phyllotis. It is reasonable to assume,
however, that the omission reflects the poor state of knowledge of
the systematics of cricetines. No doubt P. darwini, by virtue of
its wide distribution, local abundance, and aggressive instincts,
plays a frequent and prominent role in ratadas.
Reproduction.- Breeding habits of Phyllotis darwini observed by
Pearson (1951, p. 143) during 1946 in the department of Puno,
Peru, have been recorded as follows: "Males and females at Pairu-
mani [Puno, Peru, 4060 meters altitude] were not in breeding con-
dition from July 17 to 21 [1946], yet several males at Santa Rosa
[same region, 4375 meters] from July 23 to 25 [1946] had testes
9 to 10 mm. long. Pregnant females were caught at Santa Rosa
on July 28 and August 1, but at Caccachara [same region, 5000
meters] none were caught until October 5 [1946]. Pregnant females
and breeding males were caught frequently between this date and
December 19, and immature specimens were caught on December 9.
The average number of embryos was 4. In all 6 cases where the
necessary data were recorded, there were more embryos in the right
horn than in the left. The ratio of sexes was 64 males to 44 females."
Additional breeding data collected in 1951, 1952 and 1955 by
Pearson and associates and noted on the skin tags of specimens
are tabulated below (Table 15).
.< - - .s -
&
ta- 1
C
/-
b
ri
*J
C
JOJ
__ ^-(
*^ f -1
'b 4
b ^" q
-
M
^; oT us" ^ ^j ^,3 ^ ^3 ^ o" n ^^
c
o
HM
T3
T-HOOO'-HOS' lU3rH I 1 r- 1 i-H CO 1 ?DCO rH ^-1 H- 3
:i
M
C
a
C8
m
r
o
L,
t>
Q
c.
C
^
DO
*o
w
^v
3
CO
3
"o
>-5
S
73
"1
o<- o" ^- o"
c
C5
co
Of O '-s O O
.
IM
o" c^T o" o cT >J ^
u
.
C?>-s'l-s'^r>-S>-3>-90 Ol-50^< O O O l-f O O
1
d
,0
E
c"
"-C
BJ
3
o
C
K
2
^
oj
"S.
^;
OJ
X
PH
0)
4-5 4->'
N
. _J
yf
**-* t*-^
5
.
rH
s
<J
00
^^l
5
T3
C<I
T-H
S'
u
3
_.
_>
3
3
r
;
C
0)
bo
Q.
C
a
~a
~5
^03
Ills o o |M|
^ ^ bO C ^-^T C g.'3 3 3 .C
* * ^H O) ^1 l> > C TO 3 CO ^ , i* CT O
b 11 !*-! o 1 -d1^ f & . flfllll
ti rtrt22 . 3 rtSS- '^ cr.<J<I^ sL
"3 c_it_ic-(-S55 o P H w-*- 6 '^ o> co aj v r ...^V 1 ^
| i-3-!|<SJi iaa| ^ S Iflllli
J Iffafl'Si ilsl i 1 llll^ll
03 C8 O g O Cages *J S +* -Q S? * SJ .S
EH H H H^ EH S P-, PH < ^ PH PH <J M <J O <J O PH J
<s
3
H
C^J
!
(?)
:
<D
H
I
I
278
T
I
8
E
a
I
O cQ
"3 a)
X PH
, 35 * fi ^ i . * **
& |. 1 11 | s . 1 1: : .5: J
Jn <u - ^2 *>.2 < *>--B'-*-,2 w <fcj
p. co ft, 2? g. g n. >x
3 2 ? 2 -5 2 P
OT
R.
c >^
"D
15 *-
b ^. M
x ^^
s "*>
TjT cc
K
rt
3 w
" T3
*e c
a
c .
S -E
3
C -
rt >5
C ^*
o
S
b-o
C8 C
o
O
O O >-s
S
E
o "I
t-"eo TjT
. . i '-L
o cT o t-T cT m >- o o cT cT o" cT
cd
~
_, e ee rtj:: 5 i
^ C H H c* O cS CC
_C M ..5=33 m ^
C8 OO iJ'^CiT 1 2.C8
C> o^oC l ~'e hL| o22JS
OH TO cic3 3rt 2 ^^- >> - c >>2 S
s . j^agSSsfiflSsiesS ^ rt <u 3 .2,o r ^
o o -^ D C CL * Cu , " cQ cC e **^ S t C 03 CL - ft . ^
3 ^^ "73 Cl-3 O tN jAr w -^e^JMft c -T^'^. : - >MM
^ ^^ A " t- fc --
F ^ iaPllIlfla-illsllllli
62.1 g.l |=3Sg5^.g m .^a.S ^5&
O3J S^-sE-'OlZODico^iJCiiiJ E-i^E- 1
3
a
<
H
9
a s => | t
33 OJ
-5 "-5 < OJ
279
'C
Ml
00
*fcj 2j:^^::'^
^^ w, cc
g.
R, "^
a
3
s S ,
s
e o
^ a
s
a
CQ
V
i
1
2
1
3
5
y
11
a,
o
^1
*?
rH
M
< ^5
cT
^*
3 S
w
"^
/J S
t. "**
Pjj
oT
TjT
bo -G
TS S
->
"b
s
_ ^
^- '"I ^ o" I
"^
oT
T 1
i jj
* o
oT
l-H
"^ "^. '""I ^- cT *"?, <M
X * K O
^. -"-^ ^
1 1 T-l I 1
3 o
^}* CO Oi ^O r-H CO T^< ^O rH
Tf to -^f oo oo T i
t^- IO j _* CO OS
rH rH CD rH
D a
s
J _.
^ r^i
3
j C
% a
'H
^
3 J5
o^
0^
3 i5
o
cT
"
o
cT
3
o
0~
cT
o o_o o o^
O 0*
cT
t"^
-i ""^
o o o" o* o o o* ^ ^^
o "cT T}< o
o"o
co eg
3
- 03
3 m
3
1 o
*a
s c
a w
3 03
3 01
2 ^
"a
5 *V*
1
^.
. N
bo
s <J
^ T3
3 g
- 03
5 PH'
1 '
3 >
3 ^2
^
~?
;
Locality 1
Punata, Cochabamba'
Comarapa, Santa Cru
Caritaya, Tarapaca 5
Tilcara, Jujuy 6
La Paz, La Paz 8
Oruro, Oruro 8
Uyuni, Potosi 8
Villazon, Potosi 8
Limbani, Puno
& >= 3
2 %
^ o3 t; 03 a;
: C55, S-S S : c'|
OSOToo*" -<3 oo & O
EH 0-3| ^^ .5,^^ g
.OOfSaj^o-p -r-) 3
3^^^ ^o^ i 3>
i'^go'S -^lll-a
-^^OV_TZ^^ o) o3 ^r-i^ ^ S
TON&ogoPH- t .2,rt"!_o
S 1 3 8 -1 2 : c S S g
o3rSoOrtSc3o3o3o3.S
O > PH EH EH M EH H O U J
Huaylarco, Arequipa
Tincopalca, Puno
Puno, Puno
Asillo, Puno
^
H
3
a
I,
c S
O X5
O
280
ft.
> "y -
manuscript data on skin tags of specimens collected
Koford, and E. Heller (concluded).
-
1
w S
b
00
* "
o
i2
o
i~i
00
I
'VJ **? "!
'^-i t- rt
(M i-H
-HO*
oo
E
"3
