Description of a new shrew of the genus Cryptotis (Mammalia: Soricomorpha: Soricidae) from the Sierra de Aroa, an isolated mountain range in northwestern Venezuela, with remarks on biogeography and conservation

Abstract

In South America, shrews of the genus Cryptotis have a primarily Andean distribution. Based on specimens from the non-Andean Sierra de Aroa in Venezuela, we name Cryptotis aroensis sp. nov., which we assign to the C. thomasi group of thegenus owing to its possession of characters that include a relatively large body size, luxuriant fur, moderately enlargedforefeet with elongated and narrow claws, unicuspid teeth relatively narrow and concave on the posteroventral margin,ectoloph of first upper molar with the anterior element reduced relatively to the posterior element, and mandible with thearticular process not robust, high, and broad, and with the coronoid process joining the ramus at a low angle. The newspecies can be differentiated from other members of the C. thomasi group on the basis of its possession of a uniquecombination of characters, that include a rich grayish brown pelage, a narrow palate at the level of the second upper molars(no overlap in this measurement observed with 146 specimens of 10 other species of the group), nasal cavity and ethmo-turbinals partially visible in occlusal view of palate, lacrimal foramina wide and deep, tympanic process of petromastoidsshowing a minute foramen, unicuspid teeth with posterolingual cuspules, fourth unicuspid tooth labially placed, thirdupper molar complex and nearly as wide as the second upper molar, and bicuspulate lower incisors. The new species isknown from only 3 specimens obtained at the type locality, which is in a pristine patch of cloud forest at elevation 1730m, and represents the first mammalian taxon known to be endemic to the Sierra de Aroa, a small and isolated mountainrange that was previously reported to possess numerous biotic elements that are either exclusive, or shared with the muchlarger Cordillera de la Costa to the east. The clear morphological differentiation of the new species with respect to itsAndean relatives suggests that its ancestors colonized the Sierra de Aroa several glacial maxima ago, when montanevegetation belts were lower than today. The presumably optimal habitat of the new species (cloud forests of the Sierra deAroa above 1500 m) covers less than 40 km2 , and is threatened by deforestation and global climate change. Therefore, thenew species can be categorized as endangered by application of criteria B2a and E of the current “Red List Categories and Criteria” of the International Union for Conservation of Nature.