In this study, we compared a new population of Rhipidomys from the Sierra de Aroa-Yaracuy State in Venezuela with taxa included within the R. fulviventer section sensu Tribe (1996). We used geometric morphometrics from selected landmarks on the skull, and mandible of three species of Rhipidomys, and three subspecies of R. fulviventer housed in Venezuelan museums. We grouped every taxon as R. venustus Aroa (Sierra de Aroa), R. venustus (Sistema de colinas Lara-Falcón, Cordillera Central, and Andes-Cordillera de Mérida), R. wetzeli (Guayana), R. fulviventer elatturus (Andes-El Tamá), R. fulviventer ssp. 1 (Cordillera Central), and R. fulviventer tenuicauda (Cordillera Oriental). We measured every landmark with its opposite with the purpose to corroborate the results with the linear morphometrics, using the program TPSDig. The results support the proposed taxonomy that previously recognized three species, and three subspecies within R. fulviventer. However, the analysis separated R. venustus Aroa as a distinct group. The landmarks on the dorsal view showed the greatest differences in the Rhipidomys studied. R. venustus Aroa, and R. venustus were the two largest taxa, and R. wetzeli was the smallest. Among the subspecies of R. fulviventer, R. f. ssp. 1, showed less differentiation in the shape, and R. f. tenuicauda showed the strongest differentiation. The Sierra de Aroa population needs careful taxonomic revision because it may represent an undescribed taxon within R. venustus.

We report the first record of the Santa Marta mouse Nephelomys maculiventer in Venezuela based on a specimen from the Northern Andes in the Sierra de Perijá. This record increases the number of mammalian species documented in Venezuela to 404 and extends the geographic distribution range of N. maculiventer approximately 80 km northwest from the closest locality in Colombia. With this discovery, we update the ecological and conservation information for the species as well as the taxonomy of the genus Nephelomys.

The genus Nephelomys comprises at least 13 taxa with altitudinal distribution ranging from 900 to 4,000 meters above sea level. Three species are currently known to occur in Venezuela, but some authors suggest that two additional taxa are present in Venezuelan Andes populations and consider N. meridensis as a species complex. We conducted geometric morphometric analyses of skulls and jaws from populations assignable to the monotypic species N. meridensis from the Venezuelan Andes, in order to examine and compare morphological variations in this species. We compared four localities (including the type locality of N. meridensis) situated in northern, central, and western portions of Cordillera de Mérida and the Tamá páramo. We created morphological landmarks on dorsal, ventral, lateral, and jaw views of each skull using the tpsDIG software. Significant differences were found in skull shape and isometric size in most of the populations examined. The discrimination and morphological differentiation of some of these groups with respect to the population from the type locality (Mérida) were aligned with the results from multivariate and cytogenetic analyses carried out previously by other authors. Our data support recognizing N. meridensis as a species complex, comprising at least three still undescribed taxa from the Yacambú National Park (cordillera de Mérida), La Trampita (cordillera de Mérida) and the Tamá páramo (Tamá massif ). A more detailed taxonomic study of Nephelomys from Venezuela, molecular and linear morphometric analyses, and revision of morphological characters, are necessary to describe potential new taxa and determine the geographical distribution of the species in this genus.El género Nephelomys contiene al menos 13 taxa con distribuciones altitudinales desde los 900 metros sobre el nivel del mar hasta 4,000. Actualmente, tres especies ocurren en Venezuela, pero algunos autores sugieren la existencia de dos taxa adicionales en los Andes venezolanos, considerando a la especie monotípica, N. meridensis como un complejo de especies. En este estudio, se usó morfometría geométrica para comparar la forma y tamaño del cráneo en poblaciones de roedores andinos de Venezuela, asignables a la especie monotípica, N. meridensis. Se compararon cuatro localidades de N. meridensis (incluyendo la localidad tipo), ubicadas en el norte, centro y oeste de la Cordillera de Mérida y en el Páramo El Tamá. Se colocaron hitos morfológicos en las vistas dorsal, ventral, lateral y mandíbula, empleando el programa tpsDIG. Nuestros datos mostraron diferencias significativas en el tamaño isométrico (tamaño centroide) y en la forma del cráneo para la mayoría de las poblaciones evaluadas, resaltando que para algunas, su discriminación y diferenciación morfológica con la población de la localidad tipo (Mérida), coincidió con resultados multivariados y citogenéticos previamente realizados por otros autores. El presente estudio corrobora que N. meridensis tiene que ser tratado como un complejo de especies, incluyendo al menos tres tax...