< OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN eiaopv A996 DE \ 6 A5VIT l H' *"» NO VOLS DARD ECONOMY THESIS LEAF ATTACH D Q THIS TITLE j D ECONOMY ALTTH 1ST D COLOR OR TITLE I .D. PLE 20706 ra^gr )IS ISSN BIX IINDING WHEEL SYS. ID. *E CY Stf 1 3 m 1 NEW SERIF Revision of the Tribe Phyllotin (Rodentia: Sigmodontinae), with a Phylogenetic Hypothesis for the Sigmodontinae Scott J. Steppan february 28, 1995 Miblication 1464 >I I UBLISHED BY FIELD MUSEUM Ol ' - i for i n tffors Ui n thcre< reduces th ieaiion res.:. • , uete copi i copy plus two .'.id Mos-r.ui Ulmoi: . t" and n the nieti w that of r oi Style (I3ih lvcrsily ; given in '. index ot A nford .. lontai structure, md floristics. Journal of ind Si .--.. Bulletin 143, Bui Guatemala tdiana: 1 b >ns are rei in the text (not as "pU mpanicd ' I acceptable . ! < {! Dens;, ami and not exceed 11V4 i), may obtained in (preferred) it ion; and photo color : figure; corresponding autii can be made and queries ans a be made of) the s . : ON ACID FREE PAPER. Revision of the Tribe Phyllotini FIELDIANA Zoology NEW SERIES, NO. 80 Revision of the Tribe Phyllotini (Rodentia: Sigmodontinae), with a Phylogenetic Hypothesis for the Sigmodontinae Scott J. Steppan Division of Mammals Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 Committee on Evolutionary Biology The University of Chicago Chicago, Illinois 60637 Accepted July 11, 1994 Published February 28, 1995 Publication 1464 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1995 Field Museum of Natural History Library of Congress Catalog Card Number: 94-62054 ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents 8. Lateral view of a generalized Phyllotis cranium 22 9. Variation in incisor grooves among Abstract 1 phyllotines 23 Introduction 1 10. Variation in upper incisor dentine fis- Evolutionary Relationships within Sigmo- sures 23 dontinae 2 1 1 . Variation in ventromedial process of Taxonomic History of the Phyllotines ... 6 mandibular ramus 27 Materials and Methods 7 12. Position of anterior root of zygomata .. 29 Taxa and Characters Examined 7 13. Dorsal views of interorbital region .... 31 Quantitative Character Coding 10 14. Dorsolateral views of posterior cranium Analytical Methods 11 34 Comparative Morphology 13 15. Stapedial spine of auditory bulla 35 Dentition 14 16. Medial views of auditory bulla and in- Cranium and Mandible 26 ternal carotid canal 36 Postcranial Skeleton 40 17. Ventral view of hemal arches and hemal External Morphology 49 processes in Nectomys squamipes 48 Characters of the Phallus and Soft Anatomy 18. Ventral and lateral views of bacular ap- 51 paratus in Phyllotis magister 52 Phylogenetic Relationships within Sigmo- 19. Strict consensus cladogram for the Sig- dontinae 53 modontinae; analysis weighted to favor Results 53 sigmodontine monophyly 54 Discussion 60 20. Strict consensus cladogram for the Sig- Phyllotine Monophyly 62 modontinae; unweighted analysis 56 Phylogenetic Relationships within 21. Majority-rule bootstrap consensus tree Phyllotini 63 for the Sigmodontinae; analysis weight- Results 63 ed to favor sigmodontine monophyly . 58 Discussion 70 22. Strict consensus cladogram for the Phyl- Taxonomy 72 lotini 64 Acknowledgments 100 23. Eighty percent majority-rule consensus Literature Cited 101 tree, derived from most-parsimonious Appendix: Specimens Examined 104 trees wherein Punomys is not a phyllo- tine 65 24. Majority-rule bootstrap consensus tree List of Illustrations for the Phyllotini 66 25. Cranium and mandible of Calomys lau- cha 73 1 . Albumin immunological dendrogram 26. Upper and lower molars of Calomys 3 (from Sarich, 1985) laucha 74 2. Evolutionary scenario for South Ameri- 27. Cranium and mandible of Eligmodontia can sigmodontines (from Hershkovitz, morgani 76 1962) 5 28. Upper and lower molars of Eligmodon- 3. Hypothesized relationships of South tia morgani and Graomys griseoflavus . 11 American "cricetines," based on phallic 29. Cranium and mandible of Graomys gris- characters (from Hooper & Musser, eoflavus 78 1964) 6 30. Cranium and mandible of dar- 4. Nomenclature for dental elements (from Phyllotis wini 80 Reig, 1980) 9 3 1 . and 5. Phenogram and cladogram from electro- Upper lower molars of Phyllotis darwini and . phoretic data (from Spotorno, 1986) .. 10 Loxodontomys micropus 81 6. Dorsal view of a generalized Phyllotis 32. Cranium and mandible of Loxodonto- cranium 18 mys micropus 83 7. Ventral view of a generalized Phyllotis 33. Cranium and mandible of Auliscomys cranium 20 pictus 85 34. Upper and lower molars of Auliscomys List of Tables pictus and Galenomys garleppi 86 35. Cranium and mandible of Galenomys garleppi 87 1 . Species included in sigmodontine analysis 36. Cranium and mandible of Chinchillula 2 2. sahamae 89 Species included in phyllotine analysis . 8 37. Upper and lower molars of Chinchillula 3. Data matrix for the phylogenetic analysis sahamae and Andinomys edax 90 of the Sigmodontinae 12 38. Cranium and mandible of Andinomys 4. Data matrix for the phylogenetic analysis edax 92 of the Phyllotini 14 39. Cranium and mandible of Irenomys tar- 5. Vertebral counts among Neotropical sig- salis 93 modontines and selected muroids 42 40. Upper and lower molars of Irenomys 6. Distribution of selected characters among tarsalis . and Euneomys chinchilloides . 94 oryzomyine and thomasomyine genera 47 41. Cranium and mandible of Euneomys 7. Consistency and retention indexes for sig- chinchilloides 96 modontine characters 55 42. Cranium and mandible of Neotomys 8. Consistency and retention indexes for ebriosus 97 phyllotine characters 68 43. Upper and lower molars of Neotomys ebriosus and Reithrodon auritus 98 44. Cranium and mandible of Reithrodon auritus 99 VI Revision of the Tribe Phyllotini (Rodentia: Sigmodontinae), with a Phylogenetic Hypothesis for the Sigmodontinae Scott J. Steppan Abstract The phylogenetic relationships of the South American rodents of the tribe Phyllotini are reviewed, considering both the phylogenetic relationships of the phyllotines to the other sig- modontine tribes and the relationships within the phyllotines. Cladistic analysis of 40 mor- phological characters for 28 sigmodontine taxa provides a working hypothesis of sigmodontine phylogenetics, phyllotine monophyly, and likely sister-groups to the phyllotines. Five Old World and six New World cricetid taxa represent outgroups, and together they root the sigmodontine tree within a paraphyletic thomasomyine group. The analysis corroborates the recent proposal of a monophyletic oryzomyine group that includes the tetralophodont genera Holochilus, Pseu- doryzomys, and Zygodontomys. A supratribal clade is indicated that includes the Akodontini, Phyllotini, Scapteromyini, and Punomys. The distinctiveness and monophyly of the Central American tylomyine group is strongly supported. The taxonomic distribution of and variation in morphological characters of the dentition, skull, skeleton, and soft anatomy are discussed. Apparent biases in the evolutionary polarity of reductive characters are identified in detail from a broad taxonomic survey (174 species) for intra- and interspecific variation in number of vertebrae, as well as from optimization of other characters on the phylogenetic hypotheses. Conflicting results from various phylogenetic studies suggest that Sigmodon be considered Sigmodontinae incertae sedis. Pseudoryzomys and Punomys are removed from the phyllotines, and Phyllotini is diagnosed. A cladistic analysis of 35 phyllotine taxa using 98 morphological characters is presented, and the taxonomy of the phyllotine genera is revised. Species of An- dalgalomys are referred to Graomys. Removal of micropus from Auliscomys to the genus Loxodontomys is supported. The two most species-rich genera, Phyllotis and Calomys, appear to be paraphyletic, but their species relationships are insufficiently resolved to justify modifying their taxonomy at this time. Introduction inhabiting the puna, an alpine steppe community (Reig, 1986). The phyllotines constitute one of the principal This study presents a cladistic analysis of evo- radiations of the New World muroids. Frequently lutionary relationships among members ofthe tribe the most abundant mammals in their range, phyl- Phyllotini. It then provides a taxonomic revision lotine species are concentrated among the pastoral of the tribe with diagnoses of recognized genera habitats of the Andes, stretching from Ecuador to within this phylogenetic context. An impediment Tierra del Fuego, and from the Pacific coast of to any such cladistic analysis within tribes is that Peru and Chile east through Patagonia to south- intertribal relationships among Neotropical sig- eastern Brazil. Maximum diversity is achieved in modontine rodents, and even tribal monophyly, the altiplano, with 44% of the phyllotine species are poorly resolved. This lack of understanding of FIELDIANA: ZOOLOGY, N.S., NO. 80, FEBRUARY 28, 1995, PP. 1-112 Table 1 . Species included in sigmodontine analysis. higher-level relationships significantly reduces follows Musser and Carleton with (Taxonomy [1993], confidence in hypotheses of character polarities modifications noted.) and specific membership within tribes. Better es- timates ofoutgroups to the phyllotines are needed. Old World "cricetids"" Therefore, this study also presents a cladistic anal- Subfamily Calomyscinae for the Calomyscus baluchi ysis subfamily Sigmodontinae (sensu Reig, Subfamily Cricetinae 1 980) in order to provide a provisional hypothesis Cricetulus migratohus