Journal of Mammalogy, 83(3):834±842, 2002

A NEW SPECIES OF THOMASOMYS (MURIDAE: ) FROM THE ANDES OF SOUTHEASTERN PERU

LUCIÂA LUNA* AND VIÂCTOR PACHECO Division of , The Field Museum, 1400 S. Lake Shore Drive, Chicago, IL 60605-2496 and Department of Biological Sciences, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607-7060 (LL) Departamento de MastozoologõÂa, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Aptdo. 14-0434, Lima, Peru (VP)

We describe a new species of Thomasomys from the Vilcabamba Cordillera, Cuzco, Peru. This thomasomyine is a medium-sized, small-eared, and long-tailed similar in ex- ternal and cranial features to Thomasomys silvestris, a species from the western Andean slopes of Ecuador. The new species presents a unique combination of characters that in- cludes the absence of genal vibrissae, absence of a ``gap'' between the hypothenar and thenar pads, short incisive foramina, and a primitive pattern of carotid circulation. The proposed new species is known only from the type locality, suggesting that its restricted distribution could be attributed to the existence of a relict fauna in the area.

Key words: new species, Peru, rodent, Sigmodontinae, Thomasomys, Vilcabamba

In 1997, Conservation International Ecuadorean species T. silvestris and T. cau- sponsored an expedition with participants divarius (recognized here as a full species including biologists from the National Mu- by V. Pacheco) than to other species from seum of Natural History, the Smithsonian the same area. Detailed comparisons of Institution, and Museo de Historia Natural skin, cranial, and molar characters revealed of the Universidad Nacional Mayor de San it to be different from other species cur- Marcos, Peru. The team surveyed mammals rently known, and it is described in the fol- at 2 localities in the Vilcabamba Cordillera lowing. in JunõÂn and Cuzco departments, Peru at 2,050 and 3,350 m elevation. This region MATERIALS AND METHODS had been previously inventoried only by Terborgh and Weske, who surveyed the Specimens examined and acronyms of insti- tutions are listed in Appendix I. The measure- ApurõÂmac Valley collecting birds and bats ments used here are as de®ned and illustrated by along an elevational gradient of mainly Voss (1991) and Musser et al. (1998). Termi- montane forest (Koopman 1978), and by nology of external anatomy follows Brown Edmund Heller in 1915 in Macchu Picchu, (1971), cranial and dental anatomy follows a nearby locality in the department of Cuz- Hershkovitz (1962, 1994), Carleton (1980), co (Thomas 1920). Among the 16 species Carleton and Musser (1989), Voss (1991, 1993), of murids found in Vilcabamba (Emmons and Steppan (1995). Patterns of carotid arterial et al. 2001), 1 species of Thomasomys was supply follow Voss (1988). Our nomenclature captured at 3,350 m in el®n forest, the hab- for color terms follows Ridgway (1912). Age itat termed ``monte chico'' by Terborgh categories used here are as described and illus- (1971). This species is more similar to the trated by Voss (1991). Measurements are in mil- limeters (Appendix II). All external measure- * Correspondent: [email protected] ments except vibrissae length were taken in the

834 August 2002 LUNA AND PACHECOÐNEW THOMASOMYS FROM PERU 835

®eld on fresh specimens and recorded on skin Mesopterygoid fossa narrow with anterior labels. margin smoothly rounded and without me- dial process. Carotid circulation of pattern RESULTS 1 with squamosal alisphenoid groove and Thomasomys onkiro, new species sphenofrontal foramen present. Alisphenoid strut present. Upper molar toothrow with Holotype.ÐAdult female, Museo de His- weak labial cingula close to mesolophs of toria Natural, Universidad Nacional Mayor M1 and M2. de San Marcos (MUSM 13064), collected Measurements of holotype.ÐExternal by Louise H. Emmons on 14 June 1997 measurements (mm): length of head and (original ®eld number LHE 1354). The ho- body, 107; tail length, 153; length of hind lotype is a well-made skin with skull, hy- foot, 27; ear length, 20; length of dorsal fur, oid, and dentaries in good condition. 12.48; length of longest mystacial vibrissae, Paratypes include 4 specimens (skins 37.89; and length of longest superciliary vi- with skulls, dentaries, and hyoids) collected brissae, 19. from the same traplines (MUSM 13063, Cranial measurements (mm).ÐGreatest 13065, USNM 582123, 582124). length of skull, 29.37; condyloincisive Type locality.ÐPERU: Department of length, 26.32; condylomolar length, 16.64; Cuzco, Province of La ConvencioÂn, Vilca- length of rostrum, 9.44; breadth of rostrum, bamba Cordillera, eastern slope of the An- 4.45; length of orbital fossa, 8.8; length of des, between the Ene and Urubamba rivers, nasal, 10.8; breadth of nasal, 3.01; least in- 325 km northwest of city of Cuzco, terorbital breadth, 5.25; length of diastema, 11Њ39Ј36ЉS; 73Њ40Ј02ЉW, at 3,350 m eleva- 8.3; length of bony palate, 4.96; breadth of tion in el®n forest patches of Polylepis, bony palate, 6.42; postpalatal length, 9.95; Weinmannia, and Chusquea. Same type lo- length of incisive foramina, 5.41; breadth of cality as that of Cuscomys ashaninka (see incisive foramina, 1.79; length of maxillary Emmons 1999:®gure 1). toothrow, 4.56; breadth of palatal bridge, Etymology.ÐFrom the indigenous As- 3.37; breadth of 1st upper molar, 1.4; zy- haninka word ``onkiro,'' meaning mouse. gomatic breadth, 15.88; breadth of brain- The collection locality lies within the tra- case, 14.03; breadth of zygomatic plate, ditional territory of the Ashaninka people. 1.94; depth of incisor, 1.35; height of brain- Diagnosis.ÐA species of the subfamily case, 9.18; and width of mesopterygoid fos- Sigmodontinae (sensu Reig 1980). A me- sa, 2.09. This specimen belongs to tooth- dium-sized Thomasomys with soft, long, wear class 2. and dense fur; tail longer than head and Description.ÐThomasomys onkiro is a body, monocolored with tip white; pinnae medium-sized mouse with soft and long small; sides and toes of manus silvery white dorsal fur (average length ϭ 12.72 mm). and foot with metatarsals brown. Six mam- Dorsal pelage Buffy Brown, dark neutral mae. Dorsal pelage Buffy Brown, fur on gray at base with Buffy Brown tips; guard ventral side paler Buffy Yellow without hairs uniformly dark; sides with same basal pectoral lines. Genal vibrissae absent and coloration but hair tips Buff. Ventral pelage mystacial vibrissae extending a little be- tipped with Buffy Yellow; thoracic region yond posterior edge of the pinnae (in dry without pectoral lines. Chin and philtrum specimens). Six plantar pads, ¯eshy and with silvery white hairs. Mystacial, super- conspicuous. Proximal margin of hypoth- ciliary, and carpal vibrissae present. Ratio enar pad levels with distal margin of thenar of longest mystacial vibrissa to length of pad. Rostrum narrower than interorbital head-body averages 0.36. Pinnae small, breadth, anterior half of nasals slightly spat- proximally covered with long hairs of sim- ulated and projected onto sides of rostrum. ilar color to the head, outer and inner edges 836 JOURNAL OF MAMMALOGY Vol. 83, No. 3

length, from 0% (only white hair in the tip) to 16%, without apparent correlation to age or sex. Rostrum long and slender. Nasals narrow, anterior half slightly spatulated and pro- jected onto sides of rostrum. Posterior mar- gin of nasals level with or slightly anterior to lacrimals. Zygomatic notch shallow, its anterior margin posterior to nasolacrimal capsule. Interorbital region moderately broad, short, and hourglass-shaped, with smooth edges. Zygomatic arches anteriorly convergent. Skull pro®le convex with high- est part in parietals; nasofrontal surface pla- nar. Upper incisors orthodont (Hershkovitz 1962). Nasals projected slightly anterior to premaxillaries. Anterior margins of pre- maxillaries protruding like lobes. Zygomat- ic plate narrow with anterior margin straight, vertical, and posterior to nasolac- FIG. 1.ÐDetail of plantar pads of left foot of a) Thomasomys onkiro (MUSM 13064) and b) rimal capsule (Fig. 2). Jugal bone conspic- Thomasomys silvestris (USNM 513592); h, hy- uous. Squamosal alisphenoid groove, pothenar pad; t, thenar pad. Arrow indicates ab- sphenofrontal foramen, and alisphenoid sence of gap between hypothenar and thenar strut present (carotid circulation pattern 1). pads in T. onkiro and gap in T. silvestris. Tegmen tympani overlaps posterior suspen- sory process of squamosal. Flat posterior end of the thin hamular process lies on peri- with short, dark brown hairs. Outer sides of otic. Subsquamosal fenestra and postglen- the manus, wrist, and ®ngers notably white. oid foramen subequal in size (Fig. 2). Mas- Hind feet long and narrow with metatar- toid fenestra variable in shape and size. Su- sals of digits 2±4 distal to metatarsal of dig- praoccipital±parietal suture reduced. Inci- it 5. Claw of digit 5 reaches 2nd phalanx sive foramina parallel-sided, but broader at but shorter than base of claw of digit 4. premaxillary±maxillary suture, posterior Claw of digit 1 extends slightly behind in- margin of foramina separated from anterior terphalangeal joint of digit 2 (Fig. 1a). Dor- margin of M1 by an average of 0.5 mm sal surface of pes covered with dark brown (Fig. 2). Ratio of breadth of incisive foram- hair to the base of digits; from this point ina and its length averages 0.34. Upper mo- hairs gradually silvery white. Ungual tufts lar toothrows parallel. extend beyond claws of all 5 digits (Fig. Palate broad and slightly concave, the 1a). Outer margins of hind foot clothed posterior margin extending to M3 hypo- with transparent hairs. Heel covered with cone±hypo¯exus. Mesopterygoid fossa brown hair with golden tips that reach outer with anterior margin smoothly rounded and margin of pes. Plantar pads ¯eshy and con- sides parallel. Posterolateral palatal pits in- spicuous. Surface of the soles not scaly. conspicuous (Fig. 2). Roof of mesoptery- Tail is long (58±61% of total length and goid fossa complete, inconspicuous vacui- 134±153% of length of head and body), ties in lateral walls of fossa (occasional slits with scales in annular disposition and con- between presphenoid and basisphenoid su- spicuous. Hairs at base of tail cover 2±2.5 ture). Parapterygoid fossae ¯at slightly be- scales. White distal tip of tail is variable in low level of palatine. Fontanelles usually August 2002 LUNA AND PACHECOÐNEW THOMASOMYS FROM PERU 837

axis, then para¯exus and meta¯exus are di- rected around paracone and metacone. An- teromedian ¯exus is deep and becomes iso- lated with increased wear. Anterolingual and anterolabial conules are almost sube- qual. Postero¯exus is slightly deep and vis- ible until toothwear class 3 (Voss 1991). Anteroloph and mesoloph reach labial side and form a cingulum. Mesoloph of M1 is often intercepted medially by a paralophule (Hershkovitz 1994) from paracone, and me- soloph of M2 is connected in its distal end by the same structure. M2 square in shape. M3 oval-shaped with a distinct hypo¯exus (Fig. 3a, left photo). In lower toothrow, anteromedian ¯exid of m1 is shallow and anteroconid variable in shape, anterolabial and anterolingual conulids almost subequal. Cingulum pro- jects from anterolabial conulid to protoco- nid and encloses a small protolophid. Me- solophulid (Hershkovitz 1994) distinct and almost parallel to anterolophid, both reach- ing the lingual side. Ectolophids present in m1 of 3 individuals, but only ectostylids seen in m2. Mesolophid of m1 and m2 are connected distally or subdistally to entoco- nid by entolophulid (Fig. 3b, left photo). Coronoid process is subequal to condy- loid process. Angular process is anterior to FIG. 2.ÐDorsal (top), ventral (middle), and condyloid process. Capsular process of lateral (bottom) views of cranium and mandible (below cranium) of Thomasomys onkiro, new lower incisor absent. Superior and inferior species, MUSM 13064. Scale for dorsal, ventral, masseteric ridges are posterior to anterior and lateral views is 8.5 mm (top), for mandible margin of m1. Lower incisors are slender, 6.5 mm (bottom). anterior face light yellow (Fig. 2). Basihyal of hyoid arched with a wide surface and slightly concave. Tyrohyal absent. Stapedial process of bulla incon- shorter than basihyal and arched exteriorly. spicuous, lacking contact with alisphenoid. Ventral margin of basihyal irregular and Stapedial foramen and carotid canal sub- projected in its middle as an edge (obser- equal in size. Internal carotid canal bounded vation made only in 2 specimens). by petrosal and ectotympanic portions of Comparisons.ÐThomasomys onkiro can auditory bulla. Posterior opening of ali- be readily distinguished from T. caudivar- sphenoid canal small and oval-shaped. Bul- ius, which is slightly larger (average of total lae small relative to skull size. Eustachian length 264.6 versus 257; Appendix II), has tubes are distinct and extend to pterygoid longer, denser, fur of lighter tawny colora- lobes. tion, and longer Tawny Olive dorsal tips. Molars bunodont. Interpenetration of la- Ventral coloration of T. caudivarius has bial and lingual folds is only to toothrow same pattern as the buffy-tipped sides and 838 JOURNAL OF MAMMALOGY Vol. 83, No. 3

cheeks but with longer tips, which are Chamois or Buffy Cream in some speci- mens. The throat is lighter. Hind foot is lon- ger (29.7 versus 27 mm). Cranial features include mesopterygoid fossa narrower and with medial process usually present (6 out of 10 specimens in the type series, and 6 out of 7 in series from other), larger orbital fossa (9.6 versus 8.8), narrower interorbital breadth (4.8 versus 5.1), and longer molar toothrow (4.9 versus 4.6). Thomasomys onkiro requires more de- tailed comparisons with T. silvestris. Exter- nal coloration of T. onkiro is darker and more uniform than that of T. silvestris be- cause the colored tips in dorsal fur of the former are shorter. T. onkiro has darker and shorter mystacial vibrissae (ratio of longest mystacial vibrissae to length of head and body 0.36 versus 0.44), subequal to poste- rior margin of pinnae, whereas in T. silves- tris mystacials extend distinctly posterior to pinnae. Proximal margin of hypothenar pad level with distal margin of thenar pad, whereas in T. silvestris thenar and hypoth- enar pads are separated by a distinct gap (Figs. 1a and 1b). Nasals of T. onkiro protrude anteriorly beyond premaxillaries, and anterior margins of the premaxillaries are lobed, whereas in T. silvestris nasal procumbency is less dis- tinct and margins of premaxillaries are straight. Incisive foramina of T. onkiro is narrower, ratio of breadth to length of in- cisive foramina smaller (0.34 versus 0.4), and do not reach the anterior margin of M1, whereas in T. silvestris foramina usually reach anterior margin of M1 (Figs. 2 and 4). Mesopterygoid fossa of T. onkiro is nar- rower (2.1 versus 2.5), anterior margin is smoothly rounded and almost square in shape, without medial process. Here lateral margins are parallel, whereas in most of the FIG. 3.Ða) Occlusal view of upper right mo- specimens of T. silvestris the fossa is lyre- lars: Thomasomys onkiro (left, MUSM 13064), shaped, more concave anteriorly, and bi- Thomasomys silvestris (right, USNM 513592). lobed because of presence of medial small b) Occlusal view of lower right molars: T. on- process (Figs. 2 and 4). In addition, roof of kiro (left, MUSM 13064), T. silvestris (right, mesopterygoid fossa in T. onkiro has con- USNM 513592). August 2002 LUNA AND PACHECOÐNEW THOMASOMYS FROM PERU 839

gulum is short and does not reach proto- conid. Mesolophulid of T. onkiro reaches anterolophid and remains parallel-fused with it. This appears like 2 structures that reach lingual side, but in T. silvestris the corresponding structure reaches middle of anterolophid from metaconid but only the anterolophid reaches lingual side (Fig. 3b). Thomasomys onkiro presents ectolophids in m1 of 3 individuals, but only ectostylids are seen in m2, whereas ectolophids are ab- sent in m1 and m2 of T. silvestris (Fig. 3b).

DISCUSSION Sixteen species of murid rodent are known from Vilcabamba Cordillera, Cuzco, Peru (Emmons et al. 2001), a large number considering that nearby localities in Manu National Park that have been inventoried for many more years have yielded only 20 species in montane habitats (Pacheco et al. 1993). Interestingly, the number of species of the genus Thomasomys is comparable at these 2 sites (6 species from Vilcabamba Cordillera, 5 species from Manu National Park). However, no species present at Manu or other nearby sites seem as similar to T. onkiro as do T. silvestris and T. caudivar- FIG. 4.ÐDorsal (top), ventral (middle), and ius, distributed in Ecuador and northern lateral (bottom) views of cranium, and mandible Peru, respectively. The restricted distribu- (below cranium) of Thomasomys silvestris, An- tion of T. onkiro might be attributed to few- thony, 1924, from Ecuador, Pichincha, Zapa- er explorations in eastern central Peru or to dores, Rio Saloya, approximately 1,920 m the existence of a relict population of a (USNM 513592). Scale for dorsal, ventral, and once-widespread taxon. Given the exhaus- lateral views is 8.0 mm (top), for mandible 6.5 mm (bottom). tive inventories made at similar habitats in Manu National Park, Cuzco (Pacheco et al. 1993); Yanachaga-ChemilleÂn National spicuous slits in lateral walls of fossa on Park, Pasco (Pacheco et al. 1994; E. Vivar, either side of presphenoid±basisphenoid su- pers. comm.); Rio Abiseo National Park, ture, whereas in T. silvestris this is com- San MartõÂn (Leo and Romo 1992); and pletely closed. nearby localities in Bolivia, the hypothesis Compared with T. silvestris, T. onkiro of a relict species seems the most accept- has distinct M1±M2 paralophules. Labial able. cingulum at end of anteroloph and meso- Reports of new species from isolated cor- loph is more conspicuous, and M1±M2 pos- dilleras are not surprising because they may tero¯exi are deeper and distinct (Fig. 3a). not have been extensively explored previ- Thomasomys onkiro exhibits a cingulum ously. Recently, a new species of Abrocom- in m1 that projects from anterolabial con- idae, C. ashaninka, was also reported from ulid to protoconid. In T. silvestris this cin- the Vilcabamba Cordillera (Emmons 1999). 840 JOURNAL OF MAMMALOGY Vol. 83, No. 3

Among murids, T. onkiro is the 1st new lected during a Rapid Assessment Program in- species reported from this region. As was ventory at Vilcabamba Cordillera sponsored by the case with some species found in a recent Conservation International. This paper was com- survey of Rio Abiseo National Park (Gard- pleted while the senior author was supported by ner and Romo 1993), several other species a National Science Foundation grant to B. D. Patterson and colleagues (Award 9870191). V. from Vilcabamba appear to be new to sci- Pacheco's work was partially supported by an ence, but unfortunately at present most of International Graduate Student Fellowship at the them are represented only by single speci- Center for Biodiversity and Conservation, mens. AMNH. L. H. Emmons and B. D. Patterson read the manuscript of this description and offered RESUMEN helpful suggestions. Describimos una especie nueva de Tho- LITERATURE CITED masomys de la Cordillera de Vilcabamba, BROWN, J. C. 1971. The description of mammals. 1. Cuzco, PeruÂ. Este thomasomino es un roe- The external characters of the head. Re- dor de tamanÄo medio, orejas pequenÄas y view 1:151±168. cola larga, similar en caracterõÂsticas exter- CARLETON, M. D. 1980. Phylogenetic relationships in neotomine-peromyscine () and a nas y craneales a Thomasomys silvestris, reappraisal of the dichotomy within New World Cri- una especie de las vertientes occidentales cetinae. Miscellaneous Publications of the Museum del Ecuador. Esta especie presenta una of Zoology, University of Michigan 157:1±146. CARLETON, M. D., AND G. G. MUSSER. 1989. System- combinacioÂn uÂnica de caraÂcteres que inclu- atic studies of oryzomyine rodents (Muridae, Sig- ye la ausencia de las vibrisas genales, la modontinae): a synopsis of Microryzomys. Bulletin ausencia de un espacio entre los cojinetes of the American Museum of Natural History 191:1± 83. plantares hipotenar y tenar, foramenes de EMMONS, L. H. 1999. A new genus and species of los incisivos cortos y un patroÂn de circula- abrocomid rodent from Peru (Rodentia: Abrocomi- cioÂn carotõÂdea primitiva. La especie es co- dae). American Museum Novitates 3279:1±14. EMMONS, L. H., L. LUNA, AND M. ROMO. 2001. Mam- nocida solamente de la localidad tipo su- mals of the Northern Vilcabamba Mountain Range, giriendo que esta restriccioÂn podrõÂa ser atri- Peru. Pp. 105±109 in Rapid Assessment Program buõÂda a la existencia de un relicto faunõÂstico (RAP) Working Papers 12, Biological and Social Assessments of the Cordillera de Vilcabamba, Peru en el aÂrea de estudio. (L. E. Alonso, A. Alonso, T. Schulenberg, and F. G. Dallmeier, eds.). Conservation International, Wash- ACKNOWLEDGMENTS ington, D.C. GARDNER,A.L.,AND M. ROMO. 1993. A new Tho- This study was ®rst supported by the Collec- masomys (Mammalia: Rodentia) from the Peruvian tion Study Grant of the American Museum of Andes. Proceedings of the Biological Society of Natural History to L. Luna. We thank the fol- Washington 106:762±774. HERSHKOVITZ, P. 1962. Evolution of Neotropical cri- lowing curators for allowing the use of speci- cetine rodents (Muridae) with special reference to mens for comparisons and illustrations: R. S. the phyllotine Group. Fieldiana: Zoology 46:1±524. Voss (AMNH), L. Albuja (EPN), B. D. Patterson HERSHKOVITZ, P. 1994. The description of a new spe- (FMNH), R. M. Timm (KU), T. Yates (MSB), P. cies of South American hocicudo, or long-nose mouse genus Oxymycterus (Sigmodontinae, Muro- Myers (UMMZ) and M. D. Carleton (USNM). idea), with a critical review of the generic content. We thank M. D. Carleton specially for access to Fieldiana: Zoology (New Series) 1460:1±43. photographic equipment at USNM and to D. KOOPMAN, K. F. 1978. Zoogeography of Peruvian bats Schmidt (USNM) for his expert help during the with special emphasis on the role of the Andes. photographic work. We thank Conservation In- American Museum Novitates 2651:1±33. LEO, M., AND M. ROMO. 1992. DistribucioÂn altitudinal ternationalÐPuerto Maldonado, Peru, for allow- de los roedores sigmodontinos () en el ing L. Luna to use their graphic equipment to Parque Nacional Rio Abiseo, San MartõÂn, PeruÂ. vol. produce the illustrations, and B. D. Patterson for 21. Pp. 105±118 in Memorias del Museo de Historia making available supplementary graphic facili- Natural (K. R. Young and N. Valencia, eds.). Uni- versidad Nacional Mayor de San Marcos, Lima, ties. We thank L. H. Emmons and M. Romo, Peru. who collected the specimens and encouraged us MUSSER, G. G., M. D. CARLETON,E.M.BROTHERS, to describe them. These specimens were col- AND A. L. GARDNER. 1998. Systematic studies of August 2002 LUNA AND PACHECOÐNEW THOMASOMYS FROM PERU 841

oryzomyine rodents (Muridae, Sigmodontinae): di- APPENDIX I agnoses and distributions of species formerly as- signed to ``capito.'' Bulletin of the Amer- Specimens examined.ÐAcronyms for institu- ican Museum of Natural History 236:1±376. tions are as follows: American Museum of Nat- PACHECO, V., B. D. PATTERSON,J.L.PATTON,L.H. EMMONS,S.SOLARI, AND C. F. ASCORRA. 1993. List ural History (AMNH); Escuela PoliteÂcnica Na- of mammals species known to occur in Manu Bio- cional (Ecuador, EPN); Field Museum of Natu- sphere Reserve. Publicaciones del Museo de Histo- ral History (FMNH); Museo de Historia Natural, ria Natural UNMSM (A) 44:1±12. Universidad Nacional Mayor de San Marcos PACHECO, V., S. SOLARI,E.VIVAR, AND P. H OCKING. 1994. La riqueza bioloÂgica del Parque Nacional (MUSM); University of Michigan Museum of Yanachaga-ChemilleÂn. Magistri et Doctores 7:3±6. Zoology (UMMZ); United States National Mu- REIG, O. A. 1980. A new fossil of South American seum (USNM). Asterisks (*) indicate specimens cricetid rodent allied to Wiedomys, with an assess- measured (see Appendix II). ment of the Sigmodontinae. Journal of Zoology Thomasomys silvestris (46).ÐECUADOR: (London) 181:227±241. RIDGWAY, R. 1912. Color standards and color nomen- Pichincha, Zapadores, RõÂo Saloya, 1,920 m clature. 1st ed. Privately published, Washington, (USNM 513592); Pichincha, 11 km Aloag (KU D.C. 124032); Antisana, oriente (FMNH 43251); STEPPAN, S. J. 1995. Revision of the tribe Phyllotini Gualea, Ilambo Valley (FMNH 94990, 94991, (Rodentia: Sigmodontinae), with a phylogenetic hy- pothesis for the Sigmodontinae. Fieldiana: Zoology 94993±94995); Las MaÂquinas, Santo Domingo (New Series) 1464:1±112. trail, W of CorazoÂn (AMNH 66288, holotype); TERBORGH, J. 1971. Distribution of environmental gra- Old Santo Domingo trail (UMMZ 127116, dients: theory and a preliminary interpretation of 155754±155759); San JoseÂ, Occidente (FMNH distributional patterns in the avifauna of the Cordil- 53243±53247); Santa Rosa, road to Mindo lera Vilcabamba, Peru. Ecology 52:23±40. THOMAS, O. 1920. Report of the Mammalia collected (FMNH 93145, 93147±93152); Upuruni West by Mr. Edmund Heller during the Peruvian Expe- (FMNH 53407, 53408); VolcaÂn Pichincha, Or- dition of 1915 under the auspices of Yale University iente (FMNH 92000±92003); not localized and the National Geographic Society. Proceedings (EPN 954428); Pichincha, Zapadores, RõÂo Sa- of the United States National Museum 2333:217± loya, 1,920 m (USNM 513592); Pichincha, Las 249. VOSS, R. S. 1988. Systematics and ecology of ichthy- MaÂquinas, 2,100 m (AMNH 66283*, 66284*, omyine rodents (Muroidea): patterns of morpholog- 66285*, 66286*, 66287*, 66288*, 66289*, ical evolution in a small adaptive radiation. Bulletin 66291*, 66293*; USNM 270152*). of the American Museum of Natural History 188: Thomasomys onkiro (5).ÐPERU: Cuzco, La 259±493. ConvencioÂn, Vilcabamba Cordillera, 3,350 m VOSS, R. S. 1991. An introduction to the Neotropical muroid rodent genus Zygodontomys. Bulletin of the (MUSM 13063*, 13064*, 13065*; USNM American Museum of Natural History 210:1±113. 582124*; 582123*). VOSS, R. S. 1993. A revision of the Brazilian muroid Thomasomys caudivarius (15).ÐECUADOR: rodent genus Delomys with remarks on ``Thomaso- Bolivar, RõÂo Tatahuazo, 4 km E of Cruz de Liso myine'' characters. American Museum Novitates 3074:1±44. (MSB 70712, 70714); El Oro, Taraguacocha, Cordillera de Chilla (AMNH 47639, 47643*, Submitted 14 April 2001. Accepted 17 January 2002. 47655, 47659*, 47660*, 47661*, 47662*, 47664*, 47665*, 47667*, 47668* holotype, Associate Editor was Brett R. Riddle. 47669, FMNH 53978*). 842 JOURNAL OF MAMMALOGY Vol. 83, No. 3 8 8 8 8 8 8 8 9 9 9 5 5 n 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 from Ecuador 17±18.89 99±125 4.6±5.46 141±163 28.5±31 8.72±10.81 9.12±10.2 9.25±10.38 7.65±9.24 4.72±5.41 5.77±7.18 1.75±2.36 4.72±5.34 2.71±3.98 1.36±1.71 15.1±17.29 2.17±2.74 1.31±1.63 8.96±9.53 1.65±2.12 5.36±6.45 39.1±45.84 18.4±26.52 3.19±3.58 4.32±4.92 10.18±14.22 28.97±32.46 25.72±29.7 10.18±12.51 12.99±14.18 Thomasomys caudivarius 9.94 9.60 4.99 9.65 3.39 4.72 8.47 5.02 6.60 6.00 2.05 4.95 3.38 1.54 2.41 1.50 9.13 1.94 29.75 12.80 42.51 22.98 30.64 27.88 17.96 11.44 16.16 13.81 Mean Range 114.38 151.5 Thomasomys silvestris 9 9 9 9 9 9 9 8 9 n 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 3±3.63 28±30 95±127 20±26.36 1.9±2.18 139±157 10.2±11.44 1.78±2.51 3.05±3.84 1.45±1.68 4.81±5.25 7.66±8.58 4.38±5.12 8.75±10.01 8.56±10.02 4.53±5.09 8.62±9.88 1.26±1.48 9.07±9.95 2.33±2.76 5.02±6 40.4±50.9 4.65±4.96 6.24±7.33 28.75±30.34 25.41±27.52 16.66±17.51 11.01±11.81 13.02±14.1 14.79±16.28 Thomasomys silvestris 9.47 9.46 4.83 9.23 3.34 5.03 8.07 4.72 6.67 5.48 2.19 4.83 3.34 1.59 2.06 1.37 9.42 2.47 28.7 10.82 45.76 23.33 29.67 26.7 17.23 11.4 15.76 13.57 Mean Range 106.3 147.4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 n 5 5 5 5 5 5 5 from Ecuador (E1 Oro, Taraguacocha, Cordillera de Chilla). Linear measure- APPENDIX II , new species 8±9.05 26±28 19±20 19±24 94±114 3.1±3.55 4.5±4.65 1.4±1.5 144±159 9.07±10.43 8.52±9.09 10.8±11.18 3.01±3.31 4.97±5.25 4.72±5.1 1.32±1.46 8.92±9.18 1.96±2.18 6.22±6.55 5.21±6 9.44±10.81 4.45±4.68 1.79±2.09 1.94±2.26 25.45±27.33 16.38±17.1 12.45±13.31 28.69±29.99 35.61±41.32 14.89±16.17 13.29±14.03 9.75 9.79 4.58 8.85 3.15 5.13 8.45 4.9 6.37 5.59 1.92 4.56 3.32 1.44 2.09 1.37 9.02 2.07 29.33 26.55 16.8 10.94 15.68 13.71 27 19.4 12.72 38.33 22.02 Mean Range 106.4 151 Thomasomys onkiro Thomasomys caudivarius new species from Peru (Cuzco, Vilcabamba Cordillera, 3,350 m); Thomasomys onkiro, Âquinas, 2,100 m); and Measurements of Greatest length of skull Condyloincisive length Condylomolar length Condyloincisive length±condylomolar length Length of rostrum Breadth of rostrum Length of orbital fossa Length of nasal Breadth of nasal Least interorbital breadth Length of diastema Length of bony palate Breadth of bony palate Length of incisive foramina Breadth of incisive foramina Length of maxillary toothrow Breadth of palatal bridge (Pichincha, Las Ma ments are in millimeters. Breadth of 1st upperZygomatic molar breadth Breadth of braincase Breadth of zygomatic plate Depth of incisor Height of braincase Width of mesopterygoid fossa Length of head andTail body length Length of hind foot Ear length Length of dorsal fur Length of longest mystacialLength vibrissae of longest superciliary vibrissae