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Ichthyomyini, a morphologically distinctive group of Neotropical cricetid rodents, lacks an integrative study of its systematics and biogeography. Since this tribe is a crucial element of the Sigmodontinae, the most speciose subfamily of the Cricetidae, we conducted a study that includes most of its recognized diversity (five genera and 19 species distributed from southern Mexico to northern Bolivia). For this report we analyzed a combined matrix composed of four molecular markers (RBP3, GHR, RAG1, Cytb) and 56 morphological traits, the latter including 15 external, 14 cranial, 19 dental, five soft-anatomical and three postcranial features. A variety of results were obtained, some of which are inconsistent with the currently accepted classification and understanding of the tribe. Ichthyomyini is retrieved as monophyletic, and it is divided into two main clades that are here recognized as subtribes: one to contain the genus Anotomys and the other composed by the remaining genera. Neusticomys (as currently recognized) was found to consist of two well supported clades, one of which corresponds to the original concept of Daptomys. Accordingly, we propose the resurrection of the latter as a valid genus to include several species from low to middle elevations and restrict Neusticomys to several highland forms. Numerous other revisions are necessary to reconcile the alpha taxonomy of ichthyomyines with our phylogenetic results, including placement of the Cajas Plateau water rat (formerly Chibchanomys orcesi) in the genus Neusticomys (sensu stricto), and the recognition of at least two new species (one in Neusticomys, one in Daptomys). Additional work is necessary to confirm other unanticipated results, such as the non-monophyletic nature of Rheomys and the presence of a possible new genus and species from Peru. Our results also suggest that ichthyomyines are one of the main Andean radiations of sigmodontine cricetids, with an evolutionary history dating to the Late Miocene and subsequent cladogenesis during the Pleistocene. [ABSTRACT FROM AUTHOR]

As presently recognized, the genus Galea is composed of 3 species, G. musteloides, G. flavidens, and G. spixii. The most widely distributed species is G. musteloides (the common yellow-toothed cavy), ranging from southern Peru to southern Argentina and from sea level to over 4,000 m elevation. Our current taxonomic and systematic understanding of Galea is based primarily on morphological studies that have been limited in both taxonomic and geographic sampling. In this study phylogenetic analyses of sequences from the cytochrome-b gene were used to test hypotheses related to the content, limits, and systematic relationships within G. musteloides. Our data support restricting G. musteloides to the highlands of northwestern Bolivia, southeastern Peru, and extreme northeastern Chile. We elevate G. leucoblephara Burmeister, 1861, for populations occupying the lowlands of Bolivia and Paraguay to central Argentina, and we elevate G. comes Thomas, 1919, for populations from the Andes of southern Bolivia and northern Argentina. Our results also suggest the presence of a previously unrecognized form at midelevations in the southern Bolivian Andes. We find support for treating G. spixii campicola as a junior synonym of G. l. demissa and G. monasteriensis as a junior synonym of G. musteloides boliviensis. Most of the evolution of the taxa within the G. musteloides complex appears to have occurred in the Prepuna biogeographic province, with 2 independent vicariant events culminating in the separation of the G. musteloides, G. comes, and G. leucoblephara clades. Dating estimates suggest a late Miocene divergence between G. spixii and the G. musteloides group, followed by species-level divergence within the G. musteloides group during the Pliocene. [ABSTRACT FROM AUTHOR]