Revisión Taxonómica Y Biogeográfica (Con Descripción De Cinco Nuevas Especies) Del Género Atractus (Colubridae: Dipsadinae) En Los Andes De Venezuela

Abstract

Revision Taxonomica Y Biogeografica (Con Descripcion De Cinco Nuevas Especies) Del Genero Atractus (Colubridae: Dipsadinae) En Los Andes De Venezuela Presentamos una revision taxonomica y biogeografica de las serpientes del genero Atractus de la Cordillera de Merida, en los Andes de Venezuela: A. erythromelas, de selvas semicaducifolias y bosques secos montanos del Estado Merida; A. major, de selvas subandinas del Estado Tachira; A. ventrimaculatus, de selvas nubladas del Estado Merida; A. mariselae, de selvas semicaducifolias y nubladas del Estado Trujillo; A. emigdioi, de selvas nubladas de los Estados Lara, Merida y Trujillo; A. pamplonensis, de selva nublada en el Estado Tachira; A. taphorni, de selva nublada en el Estado Merida y A. univittatus, de selvas subandinas del Estado Barinas y selvas semicaducifolias del Estado Portuguesa. Adicionalmente, describimos cinco nuevas especies de esta region biogeografica: A. meridensis, de selvas semicaducifolias del Estado Merida; A. micheleae, de selvas semicaducifolias y submontanas del piedemonte andino-llanero de los Estados Merida y Tachira; A. mijaresi, de bosques siempre verdes secos montanos del Estado Merida; A. ochrosetrus, de selvas nubladas y bosques siempreverdes secos montanos del Estado Merida y A. tamaensis, de selvas nubladas del Estado Tachira. Palabras clave : Reptilia, Serpientes, Colubridae, Atractus, Cordillera de Merida, Venezuela, Taxonomia, Biogeografia. Abstract: Climate disturbances and decline of Atelopus oxyrhynchus (Amphibia: Anura) in the Venezuelan Andes. The population declines in harlequin frogs (Atelopus) has been widely documented and they appear to be related to the global amphibian decline phenomenon. One of the affected species is Atelopus oxyrhynchus, an endemic amphibian from the Chama river basin, in the Venezuelan Andes. To find answers to the species decline, we initiated the first study in Venezuela trying to relate the frog declines with local climate disturbances in temperature and recipitation. We analyzed daily, monthly and annual thermo-pluviographs for the years 1975-1990, using data from a local climate station (Santa Rosa). The later is located within a cloud forest environment that housed the last known population within the distribution range of the species. We found an apparent correlation between the years that registered unusually dry values of precipitation, with the years where drastic population declines of Atelopus oxyrhynchus occurred. Some of these years showed, besides, the highest temperatures for this period. We discuss the relationship between the duration of dry days during the “veranillo e San Juan”, a short dry period within a four-season climate regime that reign in the study area, and the population decline of this amphibian. The driest years coincided with years affected by the El Nino Southern Oscilation (ENSO). The unusually dry amounts of precipitation registered during 1982-1983, 1987 and 1989 ould have a close relationship with the population declines in Atelopus oxyrhynchus, as well as to other species in the Monte Zerpa cloud forest. Key words : Atelopus oxyrhynchus, Amphibia, climate disturbances, extinctions, Andes, Venezuela.