LIBRARY -^^i^-^^^^^C>A..A...A^-taAA=^ Oass\. V^ A_^iT:_ Publications OF FIELD MUSEUM OF NATURAL HISTORY ZOOLOGICAL SERIES Volume X Chicago, U. S. A. iQog - 1923 7/ ,5 DIAGNOSES OF NEW EAST AFRICAN MAMMALS, INCLUDING A NEW GENUS OF MURID/E. BY WILFRED H. OSGOOD, ASSISTANT CURATOR OF MAMMALOGY AND ORNITHOLOGY. The following brief descriptions are published in advance of a detailed report, now in preparation, on the Field Museum's expedi- tion to British East Africa in 1905-6. Through the courtesy of the officials of the British Museum, especially Mr. Oldfield Thomas, it has been possible to make direct comparisons with types and authenticated specimens of previously described species. The liberality of Mr. Thomas, himself at work on East African collections, in freely advising as well as in giving access to material, is most gratefully acknowledged. Procavia mackinderi zelotes subsp. nov. Type from between Naivasha and Kijabe, British East Africa. No. 17475, Field Museum of Natural History. Adult male (stage VIII). Collected January 27, 1906, by C. E. Akeley. Characters. Similar to Procavia mackinderi but smaller; pelage shorter and harsher; subterminal zone of color on hairs of shoulders and back narrower and darker. Similar to Procavia jacksoni in color but widely different in cranial characters ; skull shorter and broader throughout; nasals shorter; temporal fossae more extended posteri- orly; molariform teeth much larger and more hypsodont. Measurements. Average of 6 adults from Kijabe, measured in the flesh by E. Heller: Total length 470 (420-530); ear 32.6 (30.5-38); hind foot (c. u.) 63.5 (60-68). Skull of type: Basal length 89.5; basilar length 78; zygomatic breadth 53.2; nasals 22.5x23.4; breadth between extremities of postorbital processes 38.8; dias- tema 8.4; maxillary toothrow (crowns) 40; greatest width of mJ- 7, of m- 8.4. Remarks. Procavia slatini Sassi is evidently closely allied to P. mackinderi and the present form but no specimens representing it have been available for comparison. Since another form of the same group is known from the region intervening between the type locality of slatini and that of zelotes, it seems safe to assume that the two forms are well differentiated. S 6 Field Museum of Natural History — Zoology, Vol. X. Procavia brucei maculata subsp. nov. Type from Lukenya Mountain, British East Africa. No. 17504, Field Museum of Natural History. Adult male (stage VIII). Col- lected December 18, 1905, by C. E. Akeley. Characters. Similar to Procavia brucei and Procavia brucei hindei but color paler and more grayish throughout; underparts much less suffused with creamy or bufify, often nearly pure white; ears more whitish; dorsal spot almost entirely pure white; upper- parts more distinctly spotted than in any other member of the brucei group, the dark spots in one specimen numbering between 40 and 50 and extending from the rump to the shoulders. Skull most similar to that of hindei, differing from that of typical brucei in the character of the basisphenoid which is broad and rounded on its lower surface instead of being narrow and laterally channeled; nasals broader and less emarginate behind than in brucei; audital bullae smaller than in hindei. Measurements. Collector's measurements of an adult male: Total length 465; ear 31.5; hind foot (c. u.) 60. Skull of type: Basal length 79.7; basilar length 70; zygomatic breadth 46.5; nasals 21.2 x 19.5; breadth between extremities of postorbital proc- esses 36.3; diastema 10.4; maxillary toothrow 31.7; greatest width of m^ 5.4. Dendromus ochropus sp. nov. Type from Lake Elementeita, British East Africa. No. 167 15, Field Museum of Natural History. Adolescent male. Collected February 11, 1906, by E. Heller. Characters. i\llied to Dendroi-nus mesonielas and its relatives, but having the feet, ears, and underparts chiefly ochraceous. Upper- parts dull ochraceous, the subterminal zone of color being relatively narrow and considerably mixed with dusky, producing a slightly olivaceous effect ; black dorsal stripe well developed ; a small blackish marking on the inside of the hind leg just above the tarsal joint; underparts pale ochraceous except a patch of forwardly directed white hairs on the throat; ears well clothed inside and out with bright ochraceous hairs ; fore and hind feet ochraceous except the toes which are whitish. Somewhat similar to Dendromus nyikcB but pelage coarser, longer, and duller in color; ears ochraceous instead of dusky; feet and underparts ochraceous instead of white; tail bicolor instead of blackish all around. Skull .slightly smaller than in nyikce, with smaller bullae and shorter palatine slits. Measurements. Type: Total length 167; head and body 71; Feb., 1910. New East African Mammals — Osgood. 7 tail vertebras 96; hind foot (c. u.) 19. Skull of type: Greatest length 20.4; basilar length 14.6; zygomatic breadth 10.7; nasals 7.1; palatine slits 4.1; maxillary toothrow 3.3; length of m^- 2. Dendromus nairobse sp. nov. Type from Nairobi, British East Africa. No. 16709, Field Museum of Natural History. Old male. Collected November 6, 1905, by E. Heller. Cltaracters. Allied to Dendromus ochropus and D. nyikce but tail shorter and color much brighter; upperparts bright tawny, with the black dorsal stripe sharply contrasted; zone of tawny color relatively wide; underparts pale creamy whitish; ears pale ochraceous; feet white, slightly touched with fulvous ; tail distinctly bicolor ; inner side of hind leg without dusky spot above tarsal joint. Skull very broad, with heavy, angled zygomata, the zygomatic breadth slightly greater anteriorly than posteriorly. Measuretnents. Type: Total length 163 ; head and body 83 ; tail vertebras 85; hind foot (c. u.) 18; ear 14. Skull of type: Zygomatic breadth 11.6; nasals 8; palatine slits 3.9; maxillary toothrow 3; length of m ^- 1.7. Dendromus vvhytei pallescens subsp. nov. Type from Lukenya Mountain, British East Africa. No. 167 10, Field Museum of Natural History. Adult male. Collected Decem- ber 28, 1905, by E. Heller. Characters. Similar to Dendromus whytei but paler; general color of upperparts pale buffy ochraceous instead of tawny; under- parts creamy white , nearly pure white on chin and throat ; facial region without dusky markings; dorsal stripe obsolescent, consisting of an indistinct narrow line of dusky-tipped hairs mixed with fulvous. Measurements. Type and one topotype, respectively: Total length 147, 137; head and body 69, 60; tail vertebrae 78, 77; hind foot (c. u.) 15.5, 16; ear 11. 2, Skull of type: Greatest length 19.8; basilar length 14.8; zygomatic breadth 10.3; nasals 7.2; palatine slits 3.7; maxillary toothrow 3; length of m^- 1.8. Zelotomys gen. nov. Type. M us hilde gar decc Thomas {=Zelotomys hildegardece) . Characters. Size medium (hind foot 22-24); tail shorter than head and body; ear moderate, rounded; mammge 2-2 = 8. Skull short and broad; braincase very short; frontals but little expanded posteriorly, their supraorbital boundaries smoothly rounded; nasals 8 Field Museum of Natural History — Zoology, Vol. X. extended posteriorly beyond anterior root of zygoma and ending about on the plane of the middle of the first upper molar; inter- parietal very small. Molars very broad and more hypsodont than in Mus; first upper molar longer than second and third combined; second upper molar broader than long and very obliquely set in tooth- row ; cusps of molars numerically as in Mus; upper incisors decidedly projecting. Thamnomys surdaster polionops subsp. nov. Type from Lukenya Mountain, British East Africa. No. 17 112, Field Museum of Natural History. Adult male. Collected Decem- ber 20, 1905, by E. Heller. Characters. Similar to Thamnomys surdaster but less tawny on the sides from the nose to the flanks; sides of face, arms, and sides of body more or less olivaceous gray with slight mixture of tawny; a distinct dusky area from the eye to the base of the whiskers; upperparts bright tawny as in surdaster. Skull much as in surdaster, but averag- ing slightly larger and broader. Distinguished from Thamnomys dryas by the possession of 6 mammae instead of 4; from T. mac- millani by larger size and darker color; from T. ibeanus by smaller size, smaller ears, brighter color, and paler under sides of hind legs. Measurements. Type: Total length 284; head and body 120; tail vertebrae 164; hind foot (s. u.) 24; ear 16. Skull of type: Great- est length 30.4; basilar length 22.9; zygomatic breadth 14.3 ; nasals 11; least interorbital breadth 4.5; postpalatal length 10.5 ; diastema 7.4; palatine slits 6.8; maxillary toothrow 4.5. Thamnomys ibeanus sp. nov. Type 'from Molo, British East Africa. No. 17096, Field Museum of Natural History. Adult male. Collected March 15, 1906, by E. Heller. Characters. Size large; color dark and relatively dull; hind legs just above tarsal joint usually dark-colored all around; skull and teeth relatively large. Most similar to Thamnomys dolichurus but color darker; size larger; teeth sHghtly larger ; audital bullae smaller. Somewhat similar to T. surdaster and T. s. polionops but size larger and color duller; skull and teeth larger; audital bullae relatively small, about equalling those of polionops in actual size. Measurements. Type: Total length 329; head and body 136; tail vertebrae 193; hind foot (s. u.) 26; ear 21. Average of 8 adults from Molo, Gilgil, and Lake Elementeita: Total length 305 (290-330) ; . head and body 121 (109-136); tail vertebras 184 (174-204); hind foot Feb., 1910. New East African Mammals — Osgood. 9 (s. u.) 25.3 (24-26.5); ear 20.7 (19-22). Skull of type and an adult from Lake Elementeita, respectively: Greatest length 32.7, 31.8; basilar length 25.3, 24.4; zygomatic breadth 15.9, 14-9; nasals 11. 9, 12.3; least interorbital breadth 5, 4.7; postpalatal length 11.8, 11.2; diastema 8.4, 8; palatine slits 7.8, 7.2; maxillary toothrow 5.1, 4.6. Cricetomys gambianus kenyensis subsp. nov. Type from south side of Mount Kenya, British East Africa. No. 17517, Field Museum of Natural History. Adult male. Collected by C. E. Akeley. Characters. Most similar to Cricetomys gambianus proparator but proximal dark color of tail more extensive, occupying at least three-fifths of the length of the tail; color of upperparts somewhat paler especially on the sides which are more contrasted with the back. Skull slightly larger than in proparator; nasals broader posteriorly, their outer sides nearly parallel; rostrum slightly thicker dorso- ventrally; infraorbital plate narrower and less forwardly projecting. Somewhat similar to C. g. viator but much darker in color, with a more marked dorsal area. Measurements. Skull of type: Greatest length 76.3; basilar length 62.6; zygomatic breadth 36.5; least interorbital breadth 12; nasals 31; postpalatal length 25.5; diastema 25; palatine slits 8; maxillary toothrow 11.3. Otomys thomasi sp. nov. Type from Molo, British East Africa. No. 16698, Field Museum of Natural History. Adult female. Collected March 16, 1906, by E. Heller. Characters. Allied to Otomys irroratns tropicalis and other species having narrow nasals and m-i with seven laminae, but color widely different and skull decidedly arched or "humped." Dominant color of upperparts varying from pale cinnamon to wood brown in- stead of rich hazel as in tropicalis; a rather conspicuous patch of creamy buff behind the ears; fore and hind feet entirely creamy buff; underparts wood brown. Measurements. Type and one topotype, respectively: Total length 282, 283; head and body 184, 180; tail vertebrae 98, 103; hind foot (s. u.) 30.5, 31; ear 24, 23.5. Skull of type: Greatest length 43.3; basilar length 34.6; zygomatic breadth 21.7; length of nasals 20.7; greatest breadth of nasals 7.5; least interorbital breadth 3.4; depth from highest point of orbit to alveolar border at front of m^ 14.5; postpalatal length 1 5.1 ; palatine slits 7.5 ; maxillary toothrow 9.2; greatest width of m^- 2.5. lo Field Museum of Natural History — Zoology, Vol. X. Otomys angoniensis elassodon subsp. nov. Type from Naivasha, British East Africa. No. 16684, Field Mu- seum of Natural History. Adult female. Collected January 29, 1906, by E. Heller. Characters. Similar to Otomys angoniensis, but paler and more grayish; molars narrower; nasals broadly expanded; m'^ with seven laminae. Distinguished from Otomys nyikce canescens by slightly darker color but especially by more elongate skull, narrower brain- case, and narrower molars. Measurements. Type: Total length 270; head and body 183; tail vertebrae 87; hind foot (c. u., dry) 29; ear 21. Skull of type: Greatest length 41; basilar length 34-3; zygomatic breadth 21; length of nasals 17.7; greatest breadth of nasals 8.9; least inter- orbital breadth 4.5; depth from highest point of orbit to alveolar border at front of m^ 13.8; postpalatal length 15; palatine slits 8; maxillary toothrow 8.2; greatest width of mi- 2.4. Otomys nyikae canescens subsp. nov. Type from Kijabe, British East Africa. No. 16682, Field Museum of Natural History. iVdult male. Collected January 20, 1906, by E. HeUer. Characters. Similar in size and cranial characters to Otomys nyikce, but color much paler and grayer; general effect of upperparts grizzled wood brown or broccoli brown instead of deep russet ; nasals broadlv expanded anteriorly; m^ with seven laminae. Color much as in Otomys a. elassodon, but slightly more grayish; skull shorter and broader; molars wider. Measurements. Type and two topotypes, respectively. Total length 259, 255, 242; head and body 175, 165, 157; tail vertebrae 84, 90, 85; hind foot 29, 30, .^7.5; ear 19.5, 21, 20. Skull of type: Greatest length 37.2; basilar length 30.9; zygomatic breadth 19.6; length of nasals 17.1; greatest breadth of nasals 8.5; least inter- orbital breadth 4.6; depth from highest point of orbit to alveolar border at front of m'^ 12.8; postpalatal length 13.8; palatine shts 6.8; maxillary toothrow 8.4; greatest width of m-i 2.6. Arvicanthis barbarus convictus subsp. nov. Type from Voi, British East Africa. No. 17206, Field Museum of Natural History. Adult male. Collected April 16, 1906, by E. Heller. Characters. Allied to Arvicanthis barbarus spekei, A. b. zebra and other forms having unbroken stripes. Size about as in spekei but Feb.. 1910. New East African Mammals — Osgood. ii color decidedly more rufescent. Light stripes pale ochraceous buflF and numbering 5-6 of the heavier or primary ones and 4-5 of the secondary ones on each side. Four definite primary dark stripes on each side, each divided by a secondary light stripe. Ears bright cinnamon rufous; upper side of fore and hind feet ochraceous buff; underparts creamy buff. Skull much as in spekei but molars slightly smaller; larger and more elongate than in zebra and albolineatus. Measurements. Type: Total length 228; head and body 104 tail vertebrae 124; hind foot (c. u.) 26; ear 14.5. Skull of type Greatest length 29.9; basilar length 23.2; zygomatic breadth 13.6 nasals 11. 2; least interorbital breadth 4.5; postpalatal length 10.7 diastema 6.7; palatine slits 5.8; maxillary toothrow 5.2. Arvicanthis barbarus albolineatus subsp. nov. Type from Lukenya Mountain, British East Africa. No. 17194, Field Museum of Natural History. Adult female. Collected De- cember 14, 1905, by E. Heller. Characters. Most similar to Arvicanthis barbarus zebra but paler with lighter, more whitish stripes and decidedly paler c'rs. Some- what similar to A. b. spekei but smaller with paler stripes, paler ears, and smaller molars. Arrangement of stripes about as in zebra and convictus; light dorsal stripes pale creamy, those on the sides still lighter, almost white; median dark stripe extending forward beyond the ears; forehead and sides of face coarsely grizzled creamy; ears buff or cream buff instead of ochraceous or tawny as in allied forms; fore and hind feet buffy white. Skull with relatively short broad braincase, small molars, and good-sized audital bullae. Measurements. Type: Total length 216; head and body 102; tail vertebras 114; hind foot (c. u.) 24; ear 13. Skull of type: Great- est length 27.6; basilar length 21. i; zygomatic breadth 13. i; nasals II. I ; least interorbital breadth 4.3; postpalatal length 9.3; dias- tema 6.5; palatine slits 5.3; maxillary toothrow 5.1. Mus voi sp. nov. Type from Voi, British East Africa. No. 17062, Field Museum of Natural History. Adult male. Collected April 22, 1906, by E. Heller. Characters. Allied to Mus chrysophilus but duller in color; gen- eral tone of upperparts dull russet rather than bright ochraceous; skull with more slender nasals, lighter and narrower zygomatic plate, slightly smaller audital bulls, and shghtly smaller molars. Upper- parts dull russet brightening on the sides and face to tawn}^ ochra- 12 Field Museum of Natural History — Zoology, Vol. X. ceous; a slight dusky marking in front of and narrowly bordering the anterior half of the eye; ears thinly clothed with tawny hairs; feet creamy white; underparts creamy white, the hairs slaty at their bases; tail dusky all around, annulations lo per cm. Distinguished from Mus hindei, to which it has slight superficial resemblance, by its much longer tail and its smaller, flatter skull. Measurements. Total length 315; head and body 154; tail ver- tebras 161; hind foot (c. u.) 31; ear 19.5. Skull of type: Greatest length 36.3; basilar length 27.5; zygomatic breadth 17.9; nasals 14.7; least interorbital breadth 5.2; postpalatal length 12.6; pal- atine slits 8.2; diastema 8.2; upper toothrow 6.1. Mus niveiventris sp. nov. Type from Voi, British East Africa. No. 17099, Field Museum of Natural History. Adult female. Collected April 22, 1906, by E. Heller. Characters. Allied to Mus verreauxi and Mus hrockmdni; tail decidedly longer than head and body; mammae 3-2 = 10. Tail shorter than in brockmani -and color of upperparts very much darker. Slightly smaller than verreauxi; tail shorter; underparts entirely white with hairs white instead of slaty basally; skull smaller with relatively larger molars. Upperparts mixed buff or ochraceous buff and dusky producing a general effect of dull cinnamon to wood brown, in much worn pelage clear Mars brown; ears practically naked except near the edges where they are very thinly clothed with whitish hairs ; underparts entirely creamy white to the roots of the hairs; dusky orbital very slight and scarcely evident. Measurements. Type: Total length 262; head and body 109; tail vertebree 153; hind foot (c. u.) 23; ear 17.5. Skull of type: Greatest length 30; basilar length 23.5; zygomatic breadth 14.2; nasals 13; least interorbital breadth 4.4; postpalatal length 10.2; diastema 8.1; palatine slits 7; maxillary toothrow 4.7. Mus niveiventris subfuscus subsp. nov. Type from Lake Elementeita, British East Africa. No. 16972, ^ Field Museum of Natural History. Adult male. Collected Febru- ary 9, 1906, by E. Heller. Characters. Similar to Mus. niveiventris but slightly darker colored above and with hairs of underparts broadly slaty at bases except on middle of chin and throat; skull essentially as in nivei- ventris but braincase averaging broader. Smaller and shorter-tailed than Mus verreauxi; skull smaller; molars larger. Feb., 1910. New East African Mammals — Osgood. 13 Measurements. Type: Total length 257; head and body 105; tail vertebrae 1 48 ; hind foot (c. u.) 24; ear 17. Skull of type: Great- est length 29; basilar length 22.9; zygomatic breadth 14.7; nasals 12; least interorbital breadth 4.5; postpalatal length 10; palatine slits 6.3; diastema 7.7; maxillary toothrow 4.7. Nasilio brachyrhynchus albiventer subsp. nov. Type from Lake Elementeita, British East Africa. No. 16663, Field Museum of Natural History. Adult male. Collected Feb- ruary 9, 1906, by E. Heller. Characters. Most similar to Nasilio brachyrhynchus malosce but underparts nearly white instead of buffy; eye ring narrower; sides of face without blackish markings ; inside of ears thinly clothed with whitish instead of ochraceous hairs; upper lip and sides of "pro- boscis" whitish rather than bufiEy; general color of upperparts prac- tically as in malosce, decidedly darker than in delamerei. Measurements. Type: Total length 224; head and body 116; tail vertebrae 108; hind foot (c. u.) 31; ear 22. Skull of type: Greatest length 2>Z-?)'y basilar length 31.7; zygomatic breadth 18.7; nasals 13.5; least interorbital breadth 5.9; upper tooth series 17.4.