CYTOGENETICS OF SOME MAMMAL SPECIES FROM CENTRAL ARGENTINA by SERGIO I. TIRANTl, B.S. A THESIS IN ZOOLOGY Submitted to the Gradúate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved August, 1996 ^f5 'f\\iV 30- Ho i^'í> "h Copyright 1996, Sergio I. Tiranti ACKNOWLEDGMENTS My special thanks go to Robert J. Baker, my committee chairman, for his encouragement and support throughout my stay at Texas Tech. Committee members Robert D. Bradley and Michael R. Willig, offered comments and suggestions that benefited the final outcome of this thesis. Portions of this thesis were reviewed by John Bickham, Meredith J. Hamilton, Steve Kasper, Karen McBee and Lara E. Wiggins, thus contributing to its improvement. My work in La Pampa Province, Argentina, was supported by the Subsecretaría de Cultura, where Norma Durango, Gustavo Siegenthaler and Eduardo Fiorucci contributed in many ways to the accomplishment of this research project. Numerous localities visited in this study were sampled as part of La Pampa Province Vertébrate Survey. My stay at TTU is supported in part by the Dirección Nacional de Cooperación Internacional, Ministerio de Cultura y Educación, Argentina and the Universidad Nacional de La Pampa, Argentina. Finally, I am heartedly indebted to my parents, Iván and Irene, for their neverending encouragement and support. 11 TABLE OF CONTENTS ACKNOWLEDGMENTS ü ABSTRACT v LIST OF TABEES vi LIST OF FIGURES vii CHAPTER I. INTRODUCTION 1 II. THE KARYOTYPE OFMYQTIS.LEYIS (CHIROPTERA, VESPERTILIONIDAE). 7 Introduction...... 7 Material and Methods . 7 Results and Discussion .... 9 III. CHROMOSOMAL POLYMORPHISM VARL\TION IN THE SCRUB MOUSE AKODON MOLINAE (RODENTL\: SIGMODONTINAE) IN CENTRAL ARGENTINA 11 Abstract. 11 Introduction. 11 Material and Methods . 13 Results and Discussion . 15 IV. CYTOGENETICS OF SILKY DESERT MICE, Fí TGMODONTIA SPP. (RODENTL\: SIGMODONTINAE) IN CENTRAL ARGENTINA 20 Abstract....... 20 111 Introduction...... 20 Material and Methods 22 Results and Discussion . 23 V. CYTOGENETICS OF GRAOMYS GRISEOFLAVUS (RODENTL\: SIGMODONTINAE) IN CENTRAL ARGENTINA. ... 29 Introduction...... 29 Material and Methods . 30 Results and Discussion . 31 VI. CYTOGENETIC OBSERVATIONS ON OTHERTAXA 38 Introduction. 38 Results and Discussion . 39 VIL CONCLUSIONS 70 LITERATURE CITED 71 IV ABSTRACT This study is to assess the karyology of several small mammalian taxa in central Argentina, using chromosomes to assist in identifying species, and to provide new chromosomal data for several species from geographic áreas where studies have not been done. Specimens of small mammals, representing 24 species belonging to 6 families, were live-trapped in 26 localities in 6 provinces of central Argentina. Specimens were subjected to the standard in vivo procedure of colchicine mitotic arrest for obtaining chromosomes from bone marrow. Chromosome slides were observed and photographed and the diploid number and morphology determined for each specimen. Objectives: Clarify the systematic status of the species of silky desert mice (Eligmodontia) through a chromosomal survey of these species in west- central Argentina. Evalúate the extent of the variation associated with the chromosome 1 polymorphism in the scrub mouse Akodon molinae. Assess the widespread chromosomal variation and geographic distribution of karyotypes of Graomys griseoflavus. Key words: Cytogenetics. karyology. systematics, small mammals, central Argentina. LIST OF TABEES 1. Distribution of karyotypes in Akodon molinae 17 2. Distribution of karyotypes in Graomys griseoflavus . 34 VI LIST OF FIGURES 1 Map of Argentina showing collecting localities ... 5 2. List of localities 6 3. Karyotype of a male Myotis levis dinellii from Argentina, La Pampa Province, Caleu Caleu Department, Ahnacén El 52, TK 27903 10 4. 2n= 42 Akodon molinae karyotype. Estancia Los Toros, Toay Department, La Pampa (TK 40620, male). 18 5. Pair 1 chromosome polymorphism. a. 2n=43 (KT 40631). b. 2n= 44 (TK 40621). Estancia Los Toros, Toay Department, La Pampa . 19 6. Eligmodontia typus 2n= 44 karyotype from 25 km SE Puelén, La Pampa (TK 47613 male). ... 26 7. Eligmodontia morgani 2n= 34 karyotype from Laguna Blanca National Park, Neuquén. (TK 47602 male).. 27 8. Distribution of Eligmodontia cytotypes Neuquén and La Pampa provinces, central Argentina with collecting localities: 1. Lagima Blanca National Park. 2. 20 km E Zapala. 3. 25 km SE Puelén. 4. Cerro Colón. 5. Puesto Las Lagunitas. 6. Estancia Los Toros. Asterisks denote the 2n= 44 karyotype and the solid circle the 2n= 34 . 28 9. 2n= 42 Graomys griseoflavus karyotype (TK 49047, male) from Ulapes, La Rioja Province . 35 10. 2n= 38 Graomys griseoflavus karyotype (TK 49169, female) from La Lomita, 10 km SW Santa Rosa, La Pampa . 36 vil 11. 2n= 36 Graomys griseoflavus karyotype (TK 47611, male) from Salitral de La Perra, 25 km SE Puelén, La Pampa. 37 12. Lutreohna crassicaudata karyotype Córdoba, Arroyo ChucukTK 45615, female 51 13. Monodelphis; dimidiata karyotype Buenos Aires, Abra del Hinojo: TK 47654, male 52 14. Thylamys pusülus karyotype. Neuquén, Laguna Blanca: TK 40699, male . 53 15. Desmodus rotundus karyotype. Córdoba, Segunda Usina: TK 40674, male 54 16. Eptesicus fiírinalis karyotype, 2n= 50. La Pampa, Santa Rosa: TK 40689, female 55 17. Eumops perotis karyotype. Córdoba, Segunda Usina: TK 40676, male 56 18. Tadarida brasiliensis karyotype. Córdoba, Coronel Baigorria: TK 40665, female 57 19. Chaetophractus vellerosus karyotype. La Pampa, Naicó, Estancia Los Toros: TK 40261, female . 58 20. Abrothrix xanthorhinus Neuquén, Lagima Blanca: TK 40238, male 59 21. Akodon azarae La Pampa, Laguna Don Tomás: TK 40601, male 60 22. Akodon iniscatus Neuquén, Laguna Blanca: TK 40237, male . 61 vm 23. Bolomys sp. karyotype. La Pampa, Quehué, Estancia Los Molinos: TK 47628, male 62 24. Calomya laucha karyotype. La Pampa, Catriló: TK 47671, female 63 25. Calomvs musculinus karyotype La Pampa, Naicó, Estancia Los Toros: TK 40619, female. ... 64 26. Calomys venustus karyotype Córdoba, Espinillo: KT 49114, male. 65 27. Oligoryzomys flavescens karyotype Córdoba, Coronel Baigorria: TK 40262, female 66 28. Oxymycterus rufiís karyotype Córdoba, Espinillo: TK 49118, male 67 29. Phyllotis xanthopygus karyotype. Neuquén, Laguna Blanca: TK 40243, male 68 30. Reithrodon auritus karyotype. La Pampa, Quehué, Estancia Los Molinos: TK 47627, female . 69 IX CHAPTER I INTRODUCTION In central Argentina, it is possible to observe the convergence of a wide array of phytogeographical regions, such as the Monte Desert, physiognomically dominated by creosote-bushes (Larrea spp.); the Espinal, characterized by xerophilous scrub forests dominated by Prosopis trees; the Pampean grasslands, and towards the West and South; and the Patagonian shrub-steppe. Each of these regions possess an intermingling of subtropical and températe faunas. The Pampean Sierras, interspersed in an otherwise overwhelmingly flat terrain, offer the opportunity for the development of endemism and the isolation of species of Patagonian or Andean affinities. Additionally, salt flats with their associated biota of halophilous communities, conform distinct imits in the landscape, and harbor a iinique mammahan fauna (Braim and Mares 1995). Although recent research has produced a number of publications on the mammals of some of Argentina's provinces (Mares et al. 1989, Ojeda and Mares 1989, Bárquez et al. 1991, 1993), for many áreas of Argentina there is a virtual absence of information about the mammalian fauna; or if this information exists, it has been ascertained from classical morphological studies (e.g., Siegenthaler et al. 1990 a, b) and has not utilized other approaches, such as cytogenetics. In several cases, there is reasonable doubts about the specific status of many mammalian taxa, particularly in speciose groups such as the sigmodontine and octodontid rodents. Furthermore, other áreas, such as the westem and northwestem portions of Argentina have not been adequately surveyed in terms of its mammal fauna; as illustrated by the frequent discovery of new genera and species (Williams and Mares 1978 a, Braun and Mares 1995). Central Argentina, and especially La Pampa Province, offers the opportunity to study several small mammalian taxa for which limited cytogenetic data are currently available (Massarini et al. 1991, 1992). Chromosomal studies have been shown to be valuable for the identifícation of specific status in many animal species and have'helped resolve the status of some taxa. For example, the Patagonian scrub mice of the genus Akodon were thought to represent two different species, A. iniscatus and A. nucus, but their karyotypes have been interpreted as support to the hypothesis that only a single species, A. iniscatus, should be recognized (Barros et al. 1990). Other examples have shown the useñilness of chromosomal studies to reveal the existence, hidden from the viewpoint of classical systematics, of distinct taxa in what was thought of as a single species (Massoia et al. 1968, Baker and Genoways 1975, Cardenal et al. 1977, Liascovich et al. 1989, Liascovich and Reig 1989). Moreover, some taxa, especially among sigmodontine and octodontid rodents, show intrapopulation, interpopulation and interspecific chromosomal polymorphisms (Bianchi et al. 1969, Koop et al. 1983, Nachman 1992) which can pose problems in utilizing chromosomes to identify species. Synmorphic (moiphologically indistinguishable) or very similar taxa that had been considered