Advertisement

Mammalian Biology

, Volume 69, Issue 4, pp 238–257 | Cite as

The rediscovery of Rhagomys rufescens (Thomas, 1886), with a morphological redescription and comments on its systematic relationships based on morphological and molecular (cytochrome b) characters

  • Alexandre R. PercequilloEmail author
  • Pablo R. Gonçalves
  • João A. de Oliveira
Original investigation

Abstract

Rhagomys rufescens is one of the rarest species of the South American mammalian fauna. This scarcity has determined a lack of studies on the natural history and systematic relationships of this presumptive Atlantic forest endemic. Here we report on two recently collected specimens of Rhagomys rufescens, redescribing its morphology and discussing its phylogenetic relationships on the basis of Cytochrome b sequence data. Morphological comparisons with selected Atlantic forest species reveal that R. rufescens displays a remarkably divergent set of character states, such as a unique molar design with diagonally projected cusps and an extremely reduced first digit of hindfoot with a nail instead of a claw, resembling an additional plantar pad. These and other morphological features are suggestive of an arboreal habitus and, at least with respect to its molar morphology, a rather insectivorous diet. Molecular analysis did not allow unequivocal allocation of Rhagomys either to the oryzomyine or to the thomasomyine suprageneric assemblages, as a result of its high level of evolutionary divergence. Rhagomys seems to represent a rather divergent lineage with no clear relation to any extant sigmodontine tribe.

Key words

Rhagomys Thomasomyini Oryzomyini phylogenetic relationships 

Die Wiederentdeckung von Rhagomys rufescens (Thomas 1886), mit einer morphologischen Neubeschreibung und Kommentaren über die systematischen Beziehungen basierend auf morphologischen und molekularen (cytochrome b) Charakteren

Zusammenfassung

Rhagomys rufescens ist eine der seltensten Arten der südamerikanischen Säugetierfauna. Diese Seltenheit hat zu einer geringen Kenntnis von Lebensweise und Systematik dieser angeblich endemischen Art des atlantischen Regenwalds geführt. Hier wird über zwei jüngst gesammelte Exemplare berichtet, ihre Morphologie neu beschrieben und ihre phylogenetischen Beziehungen auf Grund von Sequenz-Daten des Cytochrome b erörtert. Morphologische Vergleiche mit anderen Arten des atlantischen Regenwaldes ergaben, daß R. rufescens eine Reihe von auffallenden divergenten Merkmalen aufweist wie das einzigartige Backenzahnmuster mit diagonal vorspringenden Höckern und ein stark reduzierter Hallux mit einem Nagel statt Klaue, einem zusätzlichen Sohlenkissen ähnlich. Diese und andere morphologische Kennzeichen bestätigen den Verdacht einer arborealen Lebensweise. Die molaren Besonderheiten weisen auf insektivore Ernährung. Die molekulare Analyse ermöglichte keine zweifelsfreie systematische Stellung von Rhagomys weder zur oryzomyinen noch zur thomasomyinen supragenerischen Gruppe als Folge seiner beträchtlichen stammesgeschichtlichen Divergenz. Rhagomys scheint eine ziemlich abweichende Gruppe zu sein mit keiner klaren Beziehung zu existierenden sigmodontinen Tribus.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bonvicino, C. R.; Moreira, M. A. M. (2001): Molecular phylogeny of the genus Oryzomys (Rodentia: Sigmodontinae) based on cytochrome b DNA sequences. Mol. Phyl. and Evolution 18, 282–292.CrossRefGoogle Scholar
  2. Bonvicino, C. R.; Oliveira, J. A.; D’Andrea, P. S.; Carvalho, R. W. (2001): The endemic atlantic forest rodent genus Phaenomys ferrugineus (Thomas, 1894) (Sigmodontinae): new data on its morphology and karyology. Bol. Museu Nacional 467, 1–12.Google Scholar
  3. Bugge, J. (1970): The contribution of the stapedial artery to the cephalic arterial supply in muroid rodents. Acta anat. 76, 313–336.CrossRefGoogle Scholar
  4. Cabrera, A. (1961): Catalogo de los Mamíferos de América del Sur. Rev. Mus. Argentino de Ciencias Naturales “Bernardino Rivadavia”. Ciencias Zoológicas 4, 309–732.Google Scholar
  5. Carleton, M. D. (1973): A survey of gross stomach morphology in New World cricetinae (Rodentia, Muroidea), with comments on functional interpretations. Misc. Publ. Mus. Zool., University of Michigan 146, 1–43.Google Scholar
  6. Carleton, M. D.; Musser, G. G. (1989): Systematic studies of oryzomyine rodents (Muridae, Sigmodontinae): a synopsis of Microryzomys. Bull. Am. Mus. Nat. Hist. 191, 1–83.Google Scholar
  7. Eisenberg, J. F.; Redford, K. H. (1999): Mammals of the Neotropics. Vol. 3. Chicago, London: University of Chicago Press.Google Scholar
  8. Ellerman, J. R. (1941): The Families and Genera of Living Rodents. Family Muridae. Vol. 2. Norwich: Jarrold and sons Ltd.Google Scholar
  9. Emmons, L. H.; Feer, F. (1997): Neotropical Rainforest Mammals, a Field Guide. 1. Chicago: University of Chicago Press.Google Scholar
  10. Felsenstein, J. (1985): Confidence limits on phytogenies: An approach using the bootstrap. Evolution 39, 783–791.CrossRefGoogle Scholar
  11. Gyldenstolpe, N. C. G. (1932): A manual of neotropical sigmodont rodents. Küngliche Svenska Vetenskapsakad, Handlinger Series 3. B. 3, 1–164.Google Scholar
  12. Hasegawa, M.; Kishino, H.; Yano, T. (1985): Dating of the human-ape splitting by a molecular clock of mitochondrial DNA. J. Mol. Evol. 21, 160–174.CrossRefGoogle Scholar
  13. Hershkovitz, P. (1962): Evolution of neotropical cricetine rodents (Muridae) with special reference to the phyllotine group. Fieldiana Zool. 46, 1–524.Google Scholar
  14. Hershkovitz, P. (1993): A new Central Brazilian genus and species of sigmodontine rodent (Sigmodontinae) transitional between akodonts and oryzomyines, with a discussion of muroid molar morphology and evolution. Fieldiana Zool. 75, 1–18.Google Scholar
  15. Kimura, M. (1980): A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J. Mol. Evol. 16, 111–120.CrossRefGoogle Scholar
  16. Kishino, H.; Hasegawa, M. (1989): Evaluation of the maximum likelihood estimate of the evolutionary tree topology from DNA sequence data, and the branching order in Hominoidea. J. Mol. Evol. 29, 170–179.CrossRefGoogle Scholar
  17. Kumar, S.; Tamura, K.; Jakobsen, I. B.; Nei, M. (2001): MEGA2: Molecular Evolutionary Genetics Analysis software. Bioinformatics 17, 1244–1245.CrossRefGoogle Scholar
  18. Maniatis, T.; Fritsch, E. F.; Sanbrook, J. (1982): Molecular Cloning. A laboratory manual. New York: Cold Spring Harbor.Google Scholar
  19. Mckenna, M. C.; Bell, S. K. (1997): Classification of Mammals above the Species Level. New York: Columbia University Press.Google Scholar
  20. Moojen, J. (1952): Os roedores do Brasil. Rio de Janeiro: Ministério da Educação e Saúde, Instituto Nacional do Livro, Biblioteca Científica Brasileira.Google Scholar
  21. Musser, G. G.; Carleton, M. D. (1993): Family Muridae. In: Mammal Species of the World: a taxonomic and geographic reference. Ed. by D. E. Wilson and D. M. Reeder. Washington: Smithsonian Institution Press. Pp. 501–755.Google Scholar
  22. Nowak, R. M. (1999): Walker’s Mammals of the World. Vol. 2. Baltimore, London: Johns Hopkins University Press.Google Scholar
  23. Reig, O. A. (1977): A proposed unified nomenclature for the enamelled components of the molar teeth of the Cricetidae (Rodentia). J. Zool. (London) 181, 227–241.CrossRefGoogle Scholar
  24. Reig, O. A. (1980): A new fossil genus of South American cricetid rodents allied to Wiedomys, with an assessment of the Sigmodontinae. J. Zool. (London) 192, 257–281.CrossRefGoogle Scholar
  25. Reig, O. A. (1984): Distribuição geográfica e história evolutiva dos roedores muróideos sulamericanos (Cricetidae: Sigmodontinae). Rev. Bras. Genética 7, 333–365.Google Scholar
  26. Ridgway, R. (1912): Color standards and nomenclature. Washington, D. C.: Published by the Author.CrossRefGoogle Scholar
  27. Smith, M. F.; Patton, J. L. (1993): The diversification of South American murid rodents: Evidence from mitochondrial DNA sequence data for the akodontine tribe. Biol. J. Linnean Soc. 50, 149–177.CrossRefGoogle Scholar
  28. Smith, M. F.; Patton, J. L. (1999): Phylogenetic relationships and the radiation of sigmodontine rodents in South America: Evidence from cytochrome b. J. Mammal. Evol. 6, 89–128.CrossRefGoogle Scholar
  29. Steppan, S. J. (1995): Revision of the Tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae. Fieldiana Zool. 80, 1–112.Google Scholar
  30. Swofford, D. L. (1999): PAUP*: Phylogenetic Analysis Using Parsimony and other methods. 4.0bl0. Sunderland, MA: Sinauer Associates.Google Scholar
  31. Tate, G. H. H. (1932): The taxonomic history of the south and central american oryzomine genera of rodents (excluding Oryzomys): Nesoryzomys, Zygodontomys, Chilomys, Delomys, Phaenomys, Rhagomys, Rhipidomys, Nyctomys, Oecomys, Thomasomys, Inomys, Aepeomys, Neacomys and Scolomys. Am. Mus. Novitates 581, 1–28.Google Scholar
  32. Thomas, O. (1886): Description of a new brazilian species of Hesperomys. Ann. Mag. Nat. Hist. 5, 250–251.CrossRefGoogle Scholar
  33. Thomas, O. (1917): On the arrangement of the South American rats allied to Oryzomys and Rhipidomys. Ann. Mag. Nat. Hist. 8, 198–200.CrossRefGoogle Scholar
  34. Voss, R. S. (1988): Systematics and ecology of Ichthyomyine rodents (Muroidea): patterns of morphological evolution in a small adaptive radiation. Bull. Am. Mus. Nat. Hist. 188, 259–493.Google Scholar
  35. Voss, R. S. (1993): A revision of the Brazilian muroid rodent genus Delomys with remarks on “Thomasomyine” characters. Am. Mus. Novitates 3073, 1–44.Google Scholar
  36. Voss, R. S.; Carleton, M. D. (1993): A new genus for Hesperomys molitor Winge and Holochilus magnus Hershkovitz (Mammalia, Muridae) with an analysis of its phylogenetic relationships. Am. Mus. Novitates 3085, 1–39.Google Scholar
  37. Wahlert, J. H. (1985): Cranial foramina of rodent. In: Evolutionary Relationships among Rodents: A multidisciplinary analysis. Ed. by W. P. Luckett and J.-L. Hartenberger. New York: Plenum Press. 92, 311–332.CrossRefGoogle Scholar

Copyright information

© Deutsche Gesellschaft für Säugetierkunde 2004

Authors and Affiliations

  • Alexandre R. Percequillo
    • 1
    Email author
  • Pablo R. Gonçalves
    • 2
  • João A. de Oliveira
    • 2
  1. 1.MastozoologiaMuseu de Zoologia da Universidade de São PauloSão PauloBrazil
  2. 2.Departamento de Vertebrados, Museu NacionalUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil

Personalised recommendations