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The systematics and taxonomy of the broadly distributed bats of the genus Cynomops has changed considerably in the last few years. Among the major changes, Cynomops abrasus was split into two species of large-bodied forms (Cynomops mastivus and C. abrasus) distributed east of the Andes. However, large Colombian specimens identified as C. abrasus from the western side of the Andes had yet to be included in any revisionary work. Phylogenetic analysis performed in this study, using mtDNA sequences (Cytochrome-b), revealed that these Colombian individuals are more closely related to Cynomops greenhalli. Morphological and molecular data allowed us to recognize populations from western Colombia, western Ecuador and northwestern Peru, as members of a new species of Cynomops. Characters that allow for its differentiation from C. greenhalli include a larger forearm, paler but more uniform ventral pelage, more globular braincase, and well-developed zygomatic processes of the maxilla (almost reaching the postorbital constriction). This study serves as another example of the importance of including multiple lines of evidence in the recognition of a new species. Given its rarity and the advanced transformation of its habitat, this new species is particularly important from a conservation perspective. [ABSTRACT FROM AUTHOR]

Necromys is a genus of sigmodontine rodent that inhabits grasslands and scrublands in South America. Eight extant species are recognized in the genus; one of these is Necromys lactens , which inhabits high-elevation grasslands in the Yungas from south-central Bolivia to northwestern Argentina. Morphological variation in N. lactens has been recognized by the description of three nominal forms. Geographically structured genetic diversity also has been observed, but a thorough revision of these nominal forms within an integrative framework has yet to be performed. We conducted a phylogeographic assessment based on an 801 base-pair fragment of the cytochrome- b gene that guided morphometric analyses (univariate and multivariate comparisons) of patterns of geographic variation in the species, and the distinction of its nominal forms. Haplotypes of N. lactens form a well-supported and geographically structured clade. Within it, there are two main clades; haplotypes from the northern range form a well-supported clade, sister and allopatric to a weakly supported southern clade, which includes variants collected at or near the type localities of three nominal forms. In turn, both main clades are composed by two allopatric subclades. Morphometric analyses indicated no differences in shape of the skull among the three nominal forms or between the recovered clades and subclades. Taking together all the available evidence, we consider N. lactens to be a monotypic species. Necromys es un género de roedor sigmodontino que habita los pastizales y arbustales de América del Sur. Se reconocen ocho especies actualmente en existencia en el género; una de ellas, Necromys lactens , habita pastizales de altura en las Yungas, desde el centro-sur de Bolivia hasta el noroeste de Argentina. Se ha reconocido variación morfológica en N. lactens con base en descripciones de tres formas nominales; también se ha observado diversidad genética geográficamente estructurada, pero una revisión exhaustiva de esas formas nominales dentro de un esquema integrativo aún no se ha llevado a cabo. Realizamos una evaluación filogeográfica basada en un fragmento de 801 pares de bases del gen citocromo b que orientó análisis morfométricos (comparaciones univariadas y multivariadas) respecto al patrón geográfico de variación de la especie y la distinción de sus formas nominales. Los haplotipos de N. lactens forman un clado bien apoyado y geográficamente estructurado. Dentro de este clado, los haplotipos del norte de su área de distribución forman un clado bien apoyado que es hermano y alopátrico con respecto de un clado austral débilmente apoyado, el cual incluye variantes colectadas en las localidades tipo de las tres formas nominales o sus cercanías. A su vez, ambos clados principales están compuestos por dos sub-clados alopátricos. Los análisis morfométricos no revelaron diferencias en la forma del cráneo entre las tres formas nominales ni entre los clados y sub-clados recuperados. Teniendo en cuenta toda la evidencia disponible, consideramos que N. lactens es una especie monotípica. [ABSTRACT FROM AUTHOR]

The nominal species Calomys tener (Winge, 1887) ranges broadly in open lands of the Caatinga, Cerrado, Pantanal and Mata Atlântica of Brazil, and was recently reported from the Pampas of southern Brazil, and in the Selva Paranaense of eastern Paraguay and northeastern Argentina. This rodent can be infected with the pathogenic Araraquara hantavirus in Brazil. Given that most epidemiological studies have not taken into account updated taxonomic findings of their rodent hosts, in this study, we obtained sequence data of the Cyt-b and COI genes of specimens of C. tener from 22 different geographical localities from throughout the currently known distribution of the species (including individuals from Argentina, Paraguay, Bolivia, and Brazil) to test if it constitutes a single genetic unit or if it presents genetic discontinuities that may represent different evolutionary lineages. Phylogenetic analyses including several species of Calomys recovered several clades with strong support. Regarding C. tener, it is recovered as sister to the node that cluster C. laucha (Fischer, 1814) sensu lato, C. expulsus (Lund, 1841) and species in the C. callosus (Rengger, 1830) species complex. At the intraspecific level there are no genetic gaps among haplotypes of C. tener that could suggest more than one species. The recent captures in the Pampas of southern Brazil and in the Selva Paranaense suggest that the species may be colonizing new geographic areas. [ABSTRACT FROM AUTHOR]

Recently, Maestri, Luza, et al. () assessed the effect of ecology and phylogeny on body size variation in communities of South American Sigmodontinae rodents. Regrettably, a cursory analysis of the data and the phylogeny used to address this question indicates that both are plagued with inaccuracies. We urge 'big data' users to give due diligence at compiling data in order to avoid developing hypotheses based on insufficient or misleading basic information. [ABSTRACT FROM AUTHOR]

Phylogenetic analyses were conducted on cytochrome b sequence data of the most geographically and taxonomically broad sampling of Cavia taxa to date. Primary objectives included providing the first extensive molecular phylogenetic framework for the genus, testing the taxonomic and systematic hypotheses of previous authors and providing insight into the evolutionary and biogeographic history of the genus. Support was found for the morphologically defined species C. aperea, C. tschudii, C. magna and C. fulgida and the taxonomic placement of taxa previously subject to conflicting taxonomic opinions (e.g. C. nana, C. anolaimae and C. guianae) was further resolved. Additionally, we elevate the Ecuadorian C. a. patzelti to species status, restrict the distributional limits and suggest taxonomic affiliations of some C. tschudii subspecies, and provide strong evidence for the geographic origin of guinea pig domestication. Finally, we provide an estimated evolutionary timeline for the genus Cavia, which appears to extend well into the late Miocene. [ABSTRACT FROM AUTHOR]

Abstract: With about 400 living species and 82 genera, rodents of the subfamily Sigmodontinae comprise one of the most diverse and more broadly distributed Neotropical mammalian clades. There has been much debate on the origin of the lineage or the lineages of sigmodontines that entered South America, the timing of entrance and different aspects of further diversification within South America. The ages of divergence of the main lineages and the crown age of the subfamily were estimated by using sequences of the interphotoreceptor retinoid binding protein and cytochrome b genes for a dense sigmodontine and muroid sampling. Bayesian inference using three fossil calibration points and a relaxed molecular clock estimated a middle Miocene origin for Sigmodontinae (∼12Ma), with most tribes diversifying throughout the Late Miocene (6.9–9.4Ma). These estimates together results of analyses of ancestral area reconstructions suggest a distribution for the most recent common ancestor of Sigmodontinae in Central-South America and a South American distribution for the most recent common ancestor of Oryzomyalia. [Copyright &y& Elsevier]