KARYOLOGY, MORPHOLOGY, AND ECOLOGY OF THOMASOMYS LANIGER AND T-NIVEIPES (RODENTIA) IN COLOMBIA

Thomasomys laniger and T. niveipes were described in the late 1800s fr om specimens taken in the Departamento de Cundinamarca (Cordillera Ori ental of the Colombian Andes). These species are similar and T. niveip es subsequently was treated as a synomym of T. laniger. Recently T. ni veipes has been listed as a distinct species. We conducted karyologica l, morphological, and ecological analyses of specimens of both species , from the Carpanta Biological Reserve, Departamento de Cundinamarca, Our results indicate that T. niveipes is a species separate from T. la niger. Diploid numbers of chromosomes are 24 and 40, respectively. Fun damental numbers (FN) are similar. The two species differ morphologica lly in coloration of the hind foot (white in T. niveipes and dark in T . laniger), height of the cranium (greater in T. niveipes), and breadt h of the interorbital region and breadth of the mesopterygoid fossa (b oth narrower in T. niveipes). We found T. laniger principally in fores t habitat and T. niveipes in paramo. T. niveipes is known only from th e departments of Cundinamarca and Boyaca at >2,900 m elevation.