We combined evidence from biogeography, craniodental traits, linear and geometric morphometrics (233 skulls), cytogenetics (karyotypes of 18 individuals) and mitochondrial DNA sequences (44 cytochrome b and 21 12S rRNA sequences) to test species limits within Otomys typus s.l. (Muridae: Murinae: Otomyini), a complex that is patchily distributed across alpine zones of Ethiopia and East Africa. Our results confirm the specific validity of O. dartmouthi, O. jacksoni, O. orestes, and O. uzungwensis, forms recently removed from synonymy under typus s.l.; support elevation of four other alpine forms to species (O. fortior, O. helleri, O. thomasi, and O. zinki); identify three additional new species (O. cheesmani sp. nov., O. simiensis sp. nov., O. yaldeni sp. nov.); and enable redefinition of O. typus s.s. as a species restricted to certain mountains west of the Great Rift Valley in Ethiopia (Simien and Guna Mountains in the north, extending to the highlands of the western rim of the Rift Valley). Phylogenetic interpretation of the cytochrome b data clearly demonstrates that the alpine morphotype once united under O. typus s.l. has originated independently at high elevations on several mountain ranges in eastern and northeastern Africa; although generally adapted to high-elevation vegetation, such alpine species are ecologically segregated from one another. Patterns of morphometric, genetic, and ecological differentiation among populations once misassigned to nominal O. tropicalis and O. typus more parsimoniously reflect regional cladogenesis along elevational gradients, rather than multiple, successive colonization by different ancestral forms from southern Africa as earlier supposed. Although incomplete and preliminary, information gathered for O. tropicalis indicates that it too is a species composite; several lines of research are discussed to redress its polyphyletic content. Our results, together with other recent taxonomic studies of Otomys, appreciably elevate the level of endemism within eastern Africa and underscore the significance of Africa's eastern highlands to the continental diversification of Otomyini.

•Based on morphological and morphometric comparisons, a new species of Hylomyscus, H. arcimontensis (Muridae: Murinae)

We describe a new species of Oecomys, O. sydandersoni (Cricetidae: Sigmodontinae), from the Parque Nacional Noel Kempff Mercado in eastern Bolivia. One of its diagnostic traits, a derived carotid circulatory plan, provides morphological evidence for its close relationship to O. concolor and O. mamorae among the 15 species of Oecomys currently recognized. Notwithstanding this shared trait, other morphological contrasts and morphometric analyses demonstrate the sharp differentiation of the eastern Bolivian form from both of those species. Oecomys sydandersoni, n. sp., is arboreal and was encountered above ground on limbs and woody vines only in densely wooded hummocks scattered through grassland, in contrast to adjacent closed tropical deciduous forest where three other species of Oecomys (O. bicolor, O. roberti, O. trinitatis) were obtained. The new species represents the fourth sigmodontine rodent to be named from this restricted region within eastern Bolivia since 1999. Its documentation served as a platform to summarize the nomenclatural history, morphological recognition, and geographic distribution of O. concolor (Wagner, 1845) and O. mamorae (Thomas, 1906) based on fresh examination of all type material and museum specimens. diagnosticas, el plan de circulation carotideo derivado, provee evidencia de su relation cercana con O. concolor y O. mamorae entre las 15 especies de Oecomys reconocidas hasta la fecha. Ademas de esta caracteristica compartida, otras caracteristicas morfologicas y analisis morfometricos demuestran la gran differentiation de la forma del este boliviano de las otras dos especies. Oecomys sydandersoni, n. sp., es una especie arboricola y fue encontrada sobre el nivel del suelo en ramas y lianas, solamente en montecillos boscosos esparcidos por la sabana, a diferencia del bosque adyacente tropical deciduo donde las otras tres especies de Oecomys (O. bicolor, O. roberti, O. trinitatis) fueron encontradas. Esta nueva especie es el cuarto roedor sigmodontino descrito para esta zona del este boliviano desde 1999. Su documentation sirve como una tribuna para compendiar la historia natural, el reconocimiento morfologico, y la distribution geografica de O. concolor (Wagner, 1845) y O. mamorae (Thomas, 1906) basados en la examination del material tipo y de especimenes de museo.

No abstract