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The current literature on marsupial phylogenetics includes numerous studies based on analyses of morphological data with limited sampling of Recent and fossil taxa, and many studies based on analyses of molecular data with dense sampling of Recent taxa, but few studies have combined both data types. Another dichotomy in the marsupial phylogenetic literature is between studies focused on New World taxa and those focused on Sahulian taxa. To date, there has been no attempt to assess the phylogenetic relationships of the global marsupial fauna based on combined analyses of morphology and molecular sequences for a dense sampling of Recent and fossil taxa. For this report, we compiled morphological and molecular data from an unprecedented number of Recent and fossil marsupials. Our morphological data consist of 180 craniodental characters that we scored for 97 terminals representing every currently recognized Recent genus, 42 additional ingroup (crown-clade marsupial) terminals represented by well-preserved fossils, and 5 outgroups (nonmarsupial metatherians). Our molecular data comprise 24.5 kb of DNA sequences from whole-mitochondrial genomes and six nuclear loci (APOB, BRCA1, GHR, RAG1, RBP3 and VWF) for 97 marsupial terminals (the same Recent taxa scored for craniodental morphology) and several placental and monotreme outgroups. The results of separate and combined analyses of these data using a wide range of phylogenetic methods support many currently accepted hypotheses of ingroup (marsupial) relationships, but they also underscore the difficulty of placing fossils with key missing data (e.g., †Evolestes), and the unique difficulty of placing others that exhibit mosaics of plesiomorphic and autapomorphic traits (e.g., †Yalkaparidon). Unique contributions of our study are (1) critical discussions and illustrations of marsupial craniodental morphology including features never previously coded for phylogenetic analysis; (2) critical assessments of relative support for many suprageneric clades; (3) estimates of divergence times derived from tip-and-node dating based on uniquely taxon-dense analyses; and (4) a revised, higher-order classification of marsupials accompanied by lists of supporting craniodental synapomorphies. Far from the last word on these topics, this report lays the foundation for future research that may be enabled by the discovery of new fossil taxa, better-preserved material of previously described taxa, novel morphological characters (e.g., from the postcranium), and improved methods of phylogenetic analysis. [ABSTRACT FROM AUTHOR]

In this report, the fourth of a revisionary series on mouse opossums (Marmosa), we treat the members of a monophyletic group of trans-Andean taxa that include M. alstoni (Allen, 1900); M. nicaraguaeThomas, 1905; and M. adleri, a new species. Although cytochrome b sequence divergence values among these species are substantially lower than distances commonly observed among other congeners, members of the Alstoni Group are strikingly unlike one another in morphological traits. We conjecture that rapid phenotypic divergence accompanied the Pleistocene radiation of an ancestral lineage that entered Central America as a late participant in the Great American Biotic Interchange. Additional undescribed species of the Alstoni Group seem likely to exist based on the evidence at hand, and we emphasize the need for renewed collecting in Central America, which has long been neglected by mammalian biodiversity researchers. [ABSTRACT FROM AUTHOR]

In this report, the second of a revisionary series on mouse opossums (Marmosa), we analyze cytochrome b sequence data from 166 specimens of the subgenus Micoureus and delimit putative species using the multirate Poisson Tree Processes (mPTP) method. That analysis identifies 21 putative species, many of which can be matched with available names, including alstoni, constantiae, demerarae, limae, germana, meridae, paraguayana, parda, perplexa, phaea, rapposa, and rutteri. However, some of these nominal taxa are not morphologically diagnosable, and in the absence of other corroborating evidence, we do not recommend that they all be recognized as valid. Phylogenetic analyses of a multigene dataset suggest that putative species of Micoureus belong to several well-supported clades, one of which (the "Rapposa Group") is revised in this report. As defined herein, the Rapposa Group includes at least three valid species: M. rapposa Thomas, 1899 (including budini Thomas, 1920); M. pardaTate, 1931; and M. rutteriThomas, 1924. Herein we document their ecogeographic distributions and diagnostic traits, comment on their taxonomic histories, and list the specimens we examined (including all relevant type material). [ABSTRACT FROM AUTHOR]

This report is the third in our monographic series on mammalian diversity and Matses ethnomammalogy in the Yavarí-Ucayali interfluvial region of northeastern Peru. Based on taxonomic analysis of specimens collected in the region, we document the occurrence of 19 species of marsupials in the genera Caluromys, Glironia, Hyladelphys, Marmosa, Monodelphis, Metachirus, Chironectes, Didelphis, Philander, Gracilinanus, and Marmosops. Our principal taxonomic results include the following: (1) we provide a phylogenetic analysis of previously unpublished mitochondrial DNA (mtDNA) sequence data for Caluromys that supports the reciprocal monophyly of all currently recognized species in the genus but reveals substantial heterogeneity in one extralimital taxon; (2) we explain why Marmosa constantiae is the correct name for the southwestern Amazonian taxon previously known as Mar. demerarae, and we diagnose Mar. constantiae from Mar. rapposa, a superficially similar species from southern Peru, eastern Bolivia, and central Brazil; (3) we explain why Mar. rutteri is the correct name for one of the Amazonian species currently known as Mar. regina, and we restrict the latter name to the transAndean holotype; (4) we recognize Metachirus myosuros as a species distinct from Met. nudicaudatus based on morphological comparisons and a phylogenetic analysis of new mtDNA sequence data; and (5) we name a new species of Marmosops to honor the late Finnish-Peruvian naturalist Pekka Soini. Of the 19 marsupial species known to occur in the Yavarí-Ucayali interfluve, 16 have been recorded in sympatry at Nuevo San Juan, the Matses village where we based most of our fieldwork from 1995 to 1999. We explain why we believe the marsupial species list from Nuevo San Juan to be complete (or nearly so), and we compare it with a species list obtained by similarly intensive fieldwork at Paracou (French Guiana). Although Nuevo San Juan and Paracou are 2500 km apart on opposite sides of Amazonia, the same opossum genera are present at both sites, the lists differing only in the species represented in each fauna. We briefly discuss current explanations for spatial turnover in species of terrestrial vertebrates across Amazonian landscapes and provide evidence that the upper Amazon is a significant dispersal barrier for marsupials. Marsupials are not important to the Matses in any way. In keeping with their cultural inattention to mammals that are inconspicuous, harmless, and too small to be of dietary significance, the Matses lexically distinguish only a few kinds of opossums, and they are not close observers of opossum morphology or behavior. [ABSTRACT FROM AUTHOR]

Based on 372 specimens examined, we integrated information from two mitochondrial and four nuclear gene sequences, morphological comparisons and morphometric analyses, as well as distributional patterns and ecological occurrences to revise the Eliurus tanala species group (Nesomyinae), a rodent complex endemic to Madagascar's forests. These evidentiary sources generally proved concordant, supporting description of a new species, E. tsingimbato, indigenous to western dry deciduous forest, mostly associated with limestone karst (tsingy); the two other members of this species group, E. ellermani and E. tanala, are restricted to eastern montane humid forest. Phylogenetic relationships among the three species were poorly resolved, suggesting that their speciation was both recent and rapid. We encountered one instance of conflict between mitochondrial DNA and all other data sources, which we interpret as incomplete lineage sorting involving a population of the new western species. Attention was focused on molecular and morphometric discrimination of the E. tanala and E. antsingy groups where their species distributions overlap in limestone-associated forests of western and northern Madagascar. Phyletic divisions demonstrated within the E. tanala species group are discussed apropos of current models of speciation identified for Malagasy forest-dwelling organisms. [ABSTRACT FROM AUTHOR]

This is the first installment of a revision of the didelphid marsupial genus Philander, commonly known as gray four-eyed opossums. Although abundant and widespread in lowland tropical forests from southern Mexico to northern Argentina, species of Philander are not well understood taxonomically, and the current literature includes many examples of conflicting species definitions and nomenclatural usage. Our revision is based on coalescent analyses of mitochondrial gene sequences, phylogenetic analyses of mitochondrial and nuclear genes, morphometric analyses, and firsthand examination of relevant type material. Based on these results, we provisionally recognize eight species, of which three are formally treated in this report: P. quica (Temminck, 1824), an Atlantic Forest endemic formerly known as P. frenatus (Olfers, 1818); P. canus (Osgood, 1913), a widespread species formerly treated as a synonym or subspecies of P. opossum (Linnaeus, 1758); and P. pebas, a new species endemic to Amazonia. The remaining, possibly valid, species of Philander can be allocated to two clades. The first is a cis-Andean complex that includes P. andersoni (Osgood, 1913); P. mcilhennyi Gardner and Patton, 1972; and P. opossum. The second is a trans-Andean complex that includes P. melanurus (Thomas, 1899) and P. pallidus (Allen, 1901). Among other nomenclatural acts, we designate a neotype for the long-problematic nominal taxon Didelphis superciliaris Olfers, 1818, and (in an appendix coauthored by Renate Angermann), we establish that Olfers' coeval binomen D. frenata is based on an eastern Amazonian type and is a junior synonym of P. opossum. [ABSTRACT FROM AUTHOR]