DIVERSITY AND DISTRIBUTION OF THE MOUSE OPOSSUMS OF THE GENUS THYLAMYS (DIDELPHIMORPHIA, DIDELPHIDAE) IN NORTHEASTERN AND CENTRAL ARGENTINA

Phylogenetic  analysis  of  a  fragment  of  the mitochondrial  genome  and  qualitative  and  quantitative  assessments  of morphological variation suggest that, in its current conception, Thylamys pusillus (Desmarest, 1804) is a complex of at least three species. In the taxonomic arrangement proposed in this work, the populations in the Argentinean provinces of Entre Ríos and Corrientes are here referred to T. citellus (Thomas, 1912), while the small Thylamys that lives in the Argentinean Dry Chaco are provisionally referred to T. pulchellus (Cabrera, 1934). In our scheme, Thylamys pusillus is restricted to the Bolivian and Paraguayan Chaco and the vicinities of northern Formosa province in Argentina. We provide emended diagnosis for T. citellus and T. pulchellus, together with detailed morphological descriptions and discuss their distinctiveness from other species of Thylamys. In addition, we included new distributional data.El análisis filogenético de un fragmento del genoma y el estudio cualitativo y cuantitativo de la morfología externa y craneana sugiere que, en su actual acepción, Thylamys pusillus (Desmarest, 1804) es un complejo de por lo menos tres especies. En el arreglo taxonómico propuesto en este trabajo, las poblaciones en las provincias argentinas de Entre Ríos y Corrientes son referidas como T. citellus (Thomas, 1912), mientras que una forma pequeña de Thylamys que habita en el Chaco Seco de Argentina es provisoriamente referida como T. pulchellus (Cabrera, 1934). En este esquema, la distribución de Thylamys pusillus es restringida al Chaco de Bolivia, Paraguay y áreas adyacentes de Argentina en el nordeste de la provincia de Formosa. Se proveen diagnosis enmendadas para T. citellus y T. pulchellus, conjuntamente con una detallada descripción morfológica de ambas entidades y una discusión de las diferencias con otras especies de Thylamys. Por ultimo, se incluyen nuevos datos de distribución.Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: D Elía, Guillermo. Universidad de Concepción; ChileFil: Flores, David Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: de La Sancha, Noé. Texas Tech University; Estados Unido

Historical biogeography, systematics, and integrative taxonomy of the non-Ethiopian speckled pelage brush-furred rats (Lophuromys flavopunctatus group)

Abstract Background The speckled-pelage brush-furred rats (Lophuromys flavopunctatus group) have been difficult to define given conflicting genetic, morphological, and distributional records that combine to obscure meaningful accounts of its taxonomic diversity and evolution. In this study, we inferred the systematics, phylogeography, and evolutionary history of the L. flavopunctatus group using maximum likelihood and Bayesian phylogenetic inference, divergence times, historical biogeographic reconstruction, and morphometric discriminant tests. We compiled comprehensive datasets of three loci (two mitochondrial [mtDNA] and one nuclear) and two morphometric datasets (linear and geometric) from across the known range of the genus Lophuromys. Results The mtDNA phylogeny supported the division of the genus Lophuromys into three primary groups with nearly equidistant pairwise differentiation: one group corresponding to the subgenus Kivumys (Kivumys group) and two groups corresponding to the subgenus Lophuromys (L. sikapusi group and L. flavopunctatus group). The L. flavopunctatus group comprised the speckled-pelage brush-furred Lophuromys endemic to Ethiopia (Ethiopian L. flavopunctatus members [ETHFLAVO]) and the non-Ethiopian ones (non-Ethiopian L. flavopunctatus members [NONETHFLAVO]) in deeply nested relationships. There were distinctly geographically structured mtDNA clades among the NONETHFLAVO, which were incongruous with the nuclear tree where several clades were unresolved. The morphometric datasets did not systematically assign samples to meaningful taxonomic units or agree with the mtDNA clades. The divergence dating and ancestral range reconstructions showed the NONETHFLAVO colonized the current ranges over two independent dispersal events out of Ethiopia in the early Pleistocene. Conclusion The phylogenetic associations and divergence times of the L. flavopunctatus group support the hypothesis that paleoclimatic impacts and ecosystem refugia during the Pleistocene impacted the evolutionary radiation of these rodents. The overlap in craniodental variation between distinct mtDNA clades among the NONETHFLAVO suggests unraveling underlying ecomorphological drivers is key to reconciling taxonomically informative morphological characters. The genus Lophuromys requires a taxonomic reassessment based on extensive genomic evidence to elucidate the patterns and impacts of genetic isolation at clade contact zones