UNI HARVARD UNIVERSITY Library of the Museum of Comparative Zoology University of Kansas Publications MUSEUM OF NATURAL HISTORY The University of Kansas Publications, Museum of Natural History, beginning with volume 1 in 1946, was discontinued with volume 20 in 1971. Shorter research papers formerly pub- lished in the above series are now published as Occasional Papers, Museum of Natural History. The Miscellaneous Pub- lications, Museum of Natural History, began with number 1 in 1946. Longer research papers are published in that series. Monographs of the Museum of Natural History were initiated in 1970. All manuscripts are subject to critical review by intra- and extramural specialists; final acceptance is at the discretion of the publications committee. Institutional libraries interested in exchanging publications may obtain the Occasional Papers and Miscellaneous Publica- tions by addressing the Exchange Librarian, University of Kan- sas Library, Lawrence, Kansas 66045. Individuals may pur- chase separate numbers of all series. Prices may be obtained upon request addressed to Publications Secretary, Museum of Natural History, University of Kansas, Lawrence, Kansas 66045. Editor: Richard F. Johnston PRINTED BY UNIVERSITY OF KANSAS PRINTING SERVICE LAWRENCE, KANSAS ^-/v/7 -t-^Luren acj vk JS. comp. zoou. OCCASIONAL PAPERS MAR 1 8 1976 °* the u^bbSt/ MUSEUM OF NATURAL HISTORY The University of Kansas Lawrence, Kansas NUMBER 47, PAGES 1-8 MARCH 1, 1976 A NEW SPECIES OF PEROMYSCUS (RODENTIA:CRICETIDAE), AND A NEW SPECIMEN OF P. SIMULATUS FROM SOUTHERN MEXICO, WITH COMMENTS ON THEIR ECOLOGY By Paul B. Robertson1 and Guy G. Musser1' From September, 1969, through August, 1970, the senior author studied the eeology of forest rodents on the Gulf-facing, north slope of the Sierra de Juarez in the State of Oaxaca, Mexico. During that time four specimens of Peromyscus differing in size and coloration from species known to occur in the region (Goodwin, 1969) were collected. Robertson worked in the same region in March, 1975 with Eric A. Rickart, when a fifth specimen was collected. Com- parison of these specimens with other species of Peromyscus indi- cates close phenotypic relationships with P. Upturns, P. lophuriis, and P. simulatus, but it is our opinion that the five specimens rep- resent a distinct, previously unnamed species, that we now name and describe below. Peromyscus chinanteco new species HoJotype. — Adult male; skin, skull, and postcranial skeleton; Museum of Natural History, The University of Kansas (KU), no. 124130; from the north slope of Cerro Pelon, 31.6 km S Vista Her- mosa, 2650 m, Oaxaca; obtained on 23 January, 1970, by Paul B. Robertson; original no. 1034. Geographic distribution. — Known only from the Gulf-facing, north slope of Cerro Pelon, Sierra de Juarez, Distrito de Ixtlan, 1 Museum of Natural History and Department of Systematica and Ecology, The Uni- versity of Kansas, Lawrence, 66045; present address: Department of Biology, Trinity University, San Antonio, Texas 78284. - Archbold Assistant Curator, Department of Mammalogy, American Museum of Natural History, New York, New York 10024. OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY Oaxaca, Mexico (presently known limits are from 21 km south of Vista Hermosa, 2000 m, to 31.6 km south of Vista Hermosa, 2650 m). Description. — Peromyscus cJiinanteco is a small member of the genus, somewhat larger externally than P. simulatus and slightly smaller than P. lophurus (Table 1). The crania of chinanteco and simulatus are similar in size ( Fig. 1 ) but differ in certain features. The dorsal pelage is grayish-brown and similar in appearance to that of many subadult Peromyscus; the underparts are grayish- white and the lateral line is well marked. The pelage is soft and thick, both dorsally and ventrally. The tail is unicolor, long rela- tive to body length, and covered with long, soft hair (measuring approximately 7 mm near the tip of the tail) that stands erect in freshly-killed specimens, giving the tail a bottlebrush appearance. The dorsal pelage of all four feet proximal to the toes is grayish- brown, while the toes are white. There is a moderately distinct, dark eye-ring and a patch of white fur from which the mystacial vibrissae arise. Comparisons. — Peromyscus chinanteco most closely resembles P. lepturus, P. lophurus, and P. simulatus, but shows the least affinity with lepturus, the only one of the three species with which it occurs sympatrically. Peromyscus lepturus is a much larger species, both externally and cranially, has different skull proportions, and has (absolutely and relatively) longer, wider, and higher-crowned cheek teeth. The available specimens of P. lophurus, a species not occurring in the state of Oaxaca, show significant geographic variation. Those from Chiapas, Mexico are smaller than those from El Salvador and Guatemala (Table 1), although similarly proportioned cranially, and approach chinanteco in size. Nevertheless, both populations average larger, externally and cranially, than chinanteco. The tail of lophurus is absolutely longer than that of chinanteco, but rela- tively shorter (tail length/body length = .98 and 1.25, respectively). The skull of lophurus is more robust than that of chinanteco; it has a relatively more elongate cranium, and relatively wider and shorter nasals (Fig. 1). The auditory bullae of lophurus are more inflated, and the anterior end of the mesopterygoid fossa is bowed in lophurus and truncate in chinanteco. Peromyscus lophurus has rela- tively larger cheek teeth than chinanteco and the posterior margins of the incisive foramina are near the middle of the first tooth. Peromyscus lophurus differs from the new species in dorsal but not ventral coloration. Both populations of lophurus are reddish- brown dorsally and grayish- white ventrallv. Unlike cJiinanteco, the entire dorsal surface of the hindfoot is light brown and there is no white spot where the mystacial whiskers arise from the skin. The third species, P. simulatus, was known from only two speci- mens from Jico, Veracruz collected by E. W. Nelson in 1893. P. SIMULATUS FROM SOUTHERN MEXICO Table 1. — External and cranial measurements of adult specimens of three species of Peromijscus (subgenus Habwmijs) from southern Mexico and Central America. i Peromyscus chinanteco Peromyscus lophurus Peromyscus lophurus Peromyscus simulatus Oaxaca Chiapas C. Araer. Veracruz Length of head and body 91.2+1.94 5 101.2+3.86 5 107.4+3.32 21 81.3+1.32 3 Length of tail 110.3+8.46 4 112.4+2.58 5 111.4+3.44 20 87.0+10.4 3 Length of hindfoot 23.4+0.48 5 21.0+0.90 5 24.1+0.32 21 22.0+1.16 3 Length of ear 17.4+0.80 5 16.4+1.36 5 18.6+0.38 21 16.0+0.0 1 Greatest length of skull 25.92+0.40 5 27.03+0.80 4 28.07+0.22 22 25.27+1.16 3 Zygomatic breadth 13.23+0.38 n O 13.95+0.12 4 14.78+0.24 22 12.93+0.54 3 Interorbital breadth 4.36+0.04 5 4.08+0.10 4 4.37+0.06 22 4.30+0.12 3 Braincase breadth 12.1+0.10 4 11.4+0.42 4 12.3+0.12 22 11.65+0.90 2 Braincase height 7.93+0.14 3 7.68+0.12 4 8.00+0.12 22 7.50+0.20 2 Length of nasals 9.96+0.24 5 10.14+0.34 5 10.70+0.14 22 9.60+.044 3 Length of rostrum 8.58+0.22 5 8.84+0.28 5 9.19+0.14 22 8.60+0.0 2 Breadth of rostrum 4.54+0.24 5 4.38+0.20 5 4.82+0.10 22 4.43+0.24 3 Breadth of zygomatic plate 1.96+0.04 5 2.20+0.08 5 2.37+0.06 22 1.97+0.18 3 Length of diastema 6.18+0.22 5 6.22+0.14 5 6.55+0.14 22 6.25+0.25 2 Incisive foramina length 4.94+0.14 5 5.86+0.20 5 5.95+0.12 22 5.17+0.30 3 Incisive foramina breadth 2.10+0.0 5 2.00+0.14 5 2.18+0.03 22 1.90+0.14 3 Palatal bridge length 4.24+0.22 5 4.08+0.08 5 4.32+0.10 22 3.75+0.30 2 Palatal bridge breadth at M1 2.70+0.0 5 2.46+0.18 5 2.73+0.10 22 2.75+0.20 2 Palatal bridge breaddi at M3 3.04+0.08 5 2.62+0.14 5 2.89+0.08 22 2.75+0.20 2 Breadth 1.88+0.44 mesopterygoid fossa 5 1.88+0.08 5 2.05+0.06 22 1.67+0.14 3 Post-palatal length 8.85+0.20 4 9.45+0.32 4 9.92+0.06 21 8.93+0.58 3 Breadth across incisor tip 1.54+0.10 3 5 1.58+0.12 5 1.63+0.04 22 1.43+0.06 3 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY Table 1. — (Cont. ) Peromyscus Peromyscus Peromyscus Peromyscus chinanteco lophurus lophurus simulatus Oaxaca Chiapas C. Amer. Veracruz Alveolar 4.18+0.04 4.84+0.08 5.19+0.08 3.97+0.18 length M1— M3 5 5 22 3 Length of 4.43+0.06 4.75+0.18 4.96+0.04 4.37+0.06 bulla 3 4 21 3 1 Measurements for males and females are combined. External measurements are those of the collectors and were taken from labels attached to the skins. Limits of the measure- ments are defined in Musser (1970). The mean, plus and minus two times the standard error of the mean, range, and sample size are listed, in that order, for each dimension. Robertson found a third specimen of P. simulatus (adult female, KU 83263, from 3 km W Zacualapan, 6000 ft, Veracruz, Fig. 1) which had been identified as P. boylii levipes. Its external and cranial characters are approximately the same as those of the holo- type (Osgood, 1904). Peromyscus simulatus is the most similar to chinanteco, but there are distinct differences between the two. Ex- ternally, chinanteco is larger than simulatus, and has a tail which is both absolutely and relatively longer (tail length /body length = 1.02 for simulatus). The species resemble each other in size, pro- portions, and robustness of the skulls, but chinanteco has a narrower and slightly longer nasal bone, and the cranium is slightly more inflated ( Fig. 1 ) . The teeth are of similar size and complexity, and the anterior margin of the mesopterygoid fossa of both species is truncate. In chinanteco the posterior margins of the incisive foram- ina end well before the level of the first cheek tooth, where in simulatus the margin is near the middle portion of the first tooth. The dorsal pelage of simulatus is reddish-brown like that of Upturns and lophurus, but its venter is distinctly whiter than that of chi- nanteco. Relationships. — Peromyscus chinanteco is most closely related to simulatus and, therefore, a member of the subgenus Habromys (Hooper, 1988), which also contains lophurus and lepturus. It seems plausible that chinanteco, lophurus, simulatus, and possibly lepturus evolved from the same parental stock, which became geo- graphically disjunct, resulting in speciation. Ecology. — The five known specimens of P. chinanteco were caught in snap traps baited with rolled oats and peanut butter and set on the ground in pine-oak cloud forest habitat. At all three capture localities the trees are festooned with orchids, ferns, and bromeliads; the undergrowth is thick and wet year-round, and many of the tree trunks are moss-covered. Pines are widely scat- 3red and uncommon. All five rodents were taken at night in open- ings beneath and among roots. The other species of this subgenus P. SIMULATUS FROM SOUTHERN MEXICO Fie;. 1. — Dorsal, ventral, and lateral views of crania. From top to bottom: P. simulatus (KU No. 83263, adult female), P. chinanleco ( KU No. 124129, adult male), Peromijscus lophurus ( KU No. 66503, adult male). 6 OCCASIOxNAL PAPERS MUSEUM OF NATURAL HISTORY also inhabit wet forests at high to moderate elevations. Rainfall in this region averages over 575 cm (230 in) per year (Robertson, 1975). At Cerro Pelon, the type locality, and at a locality 28 km south of Vista Hermosa, chinanteco was taken in the same traplines and habitat as Microtus mexicanus, Oryzomys alfaroi, Peromyscus lep- turus, P. thomasi, and Reithrodontomys mexicanus. Peromyscus boylei, P. melanocarpus, and P. oaxacensis were taken in adjacent, disturbed habitats at both localities. At 21 km south of Vista Her- mosa chinanteco was taken in close association with Microtus mexicanus, Nyctomys sumichrasti, Oryzomys alfaroi, Peromyscus melanocarpus, P. thomasi, and Reithrodontomys mexicanus. In comparison with its congeners at all localities, it is the smallest species (Fig. 2). Peromyscus lepturus is about two and a half times as large (weight) as chinanteco, and melanocarpus is almost three times as large (Robertson, 1975). The sympatric cricetid closest in size is O. alfaroi, which is 1.6 times larger. This difference in body size probably permits division of particulate food resources by size between the two species. Of the six Peromyscus shown in Figure 2, chinanteco has the highest ratio of tail length to body length. Horner (1954) and Robertson (1975) demonstrated a positive relationship between degree of arboreality and this ratio in a number of genera, includ- ing Peromyscus. The high ratio found in chinanteco suggests that it is largely arboreal, and this may explain why this species appears to be so rare. An adult female taken on February 25 (dry season) contained one embryo and had one old uterine scar; another taken on July 13 had two old scars which appeared to be the same age. The stomachs of three individuals were empty, while the stom- achs of the other two contained whitish, pulpy material that ap- peared to be well-masticated seeds. The specimen of P. simidatus was taken by M. R. Lee on 12 April 1960. In his field notes, Lee wrote, "The large, most abundant species [P. angustirostris] was taken most commonly around rocks and water seeps. 8 of these were taken. 3 smaller mice which I think may be P. boylii. One still smaller mouse with long, well- haired tail ? [P. simidatus]. The 4 smaller mice seemed not as de- pendent upon rocks and water, but were taken near low bushes." Lee's notes indicate that this was wet, dense evergreen forest, the same forest zone (humid upper tropical subzone) from which Nel- son took the first two specimens (Goldman, 1951). Lee found P. angustirostris to be very common; one specimen of Reithrodontomys fulvescens was also taken. Remarks. — R. chinanteco is named after an indigenous Oaxacan P. SIMULATUS FROM SOUTHERN MEXICO Fig. 2. — Dorsal views of crania of adult specimens of the species of Peromyscus occurring sympatrically with P. chinanteco, in Oaxaca. From left to right, top: Peromyscus ihomasi, P. melanocarpus, P. oaxacensis; bottom: P. Icpturus, P. boylei, P. chinanteco. people, the Chinantecos, who are also restricted in present distri- bution to the same general region. Specimens Examined Peromyscus chinanteco. — MEXICO: Oaxaca: N slope Cerro Pelon, 31.6 km S Vista Hermosa, 2650 m, 3 (KU); 28.6 km S Vista Hermosa, 2350 m, 1 (KU); 21 km S Vista Hermosa, 2000 m, 1 (KU). Peromyscus lophurus.— GUATEMALA: Calel, 2 (USNM); Todos Santos, S500 ft, 6 (USNM); Dept. San Marcos, Volcan Tojumulco, S slope, 10,000 ft, 1 (UMMZ); Dept. Huehuetenango, San Mateo Ixtatlan, 4 km NW Sta. Eulalia, Yayguich, 2950 m, 15 8 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY (UMMZ); 2 mi S San Juan Ixcoy, 9340 ft, 8 (KU). EL SALVA- DOR: Dept. Chalatenango, E slope Los Esesmiles, 8000 ft, 3 (MVZ). MEXICO: Chiapas: . Triunfo, 1950 m, 6 (UMMZ); San Cristobal de las Casas, Cerro Tzontehuitz, 3000 m, 1 (UMMZ); San Cristobal de las Casas, 4 (USNM). Peromyscus simulatus: — MEXICO: Veracruz: Xico, 2 (USNM); 3 km W Zacualapan, 6000 ft, 1 (KU). Acknowledgments We wish to thank Robert S. Hoffmann and Kris Johnson for reading the manuscript and for making many helpful suggestions. Janalee P. Caldwell and Eric A. Rickart aided the senior author in the field. We are grateful to the following persons for allowing us to examine specimens under their care: Charles O. Handley, Jr., National Museum of Natural History, Smithsonian Institution (USNM); Robert S. Hoffmann, Museum of Natural History, The University of Kansas (KU); Emmett T. Hooper, University of Michigan, Museum of Zoology (UMNZ); James Patton, University of California, Museum of Vertebrate Zoology (MVZ). During the course of this work the senior author was supported by grants from the Committee on Systematic Evolutionary Biology (NSF CB- 8785); The Organization for Tropical Studies; and the Watkins and Saul Funds of the Museum of Natural History, The University of Kansas. Literature Cited Goldman, E. A. 1951. Biological investigations in Mexico. Smithsonian Misc. Coll., 115:1-476. Goodwin, G. G. 1969. Mammals from the state of Oaxaca, Mexico, in the American Museum of Natural History. Bull. Amer. Mus. Nat. Hist., 141:1-269. Hooper, E. T. 1968. Classification, pp. 27-70 In Biology of Peromyscus (Bodentia), (J. King, ed.) Amer. Soc. Mamm. Spec. Publ. no. 2, 593 pp. Horner, B. E. 1954. Arboreal adaptations of Peromyscus, with special refer- ence to use of the tail. Contribs. Lab. Vert. Biol. Univ. Mich. no. 28:1- 84. Musser, G. G. 1970. Species-limits of Rattus hrahma, a murid rodent of northeastern India and northern Burma. Amer. Mus. Novits. no. 2406:1-27. Osgood, W. H. 1904. Thirty new mice of the genus Peromyscus from Mexico and Guatemala. Proc.'Biol. Soc. Wash. 17:55-77. Bobertsox, P. B. 1975. Beproduction and community structure of rodents over a transect in southern Mexico. Ph.D. thesis, Univ. of Kansas. Date Due APrs-nm Oti c- erne Bookbinding Co., Inc. 300 Summer Street Boston. Mass. 02210 3 2044 093 361 665