Jorge H. Valdez-Villavicencio

A coastal population of Large-blotched Ensatina Ensatina klauberi (Caudata: Plethodontidae) in Baja California, México

We found a new population of Ensatina klauberi in San Quintin volcanic field, Baja California. It represents the first coastal population of this species. This record extends the species range ca. 71 km southwest of the southernmost record of E. klauberi in the Sierra San Pedro Martir and represents the first population discovered outside of coniferous and pine-oak woodlands.

African clawed frog (Xenopus laevis) in Baja California: a confirmed population and possible ongoing invasion in Mexican watersheds

Abstract The African clawed frog (Xenopus laevis) is an invasive amphibian in at least 15 countries. In Mexico, only occasional records have documented it in the state of Baja California. In May 2013, we discovered a population at Puente el Morro in Rosarito. In a 1-h session of trapping, we captured 106 individuals (adults and juveniles) at a small pond. We did not see eggs, tadpoles, or reproductive activity, but lengths of frogs indicate that some have reached sexual maturity. This discovery indicates the need for conservation plans and action against X. laevis dispersion, especially in Mediterranean zone climates.

Herpetofauna Associated with Palm Oases Across the Californian-Sonoran Transition in Northern Baja California, Mexico

Abstract Ecological boundaries have been of interest to naturalists since the time of Darwin and Wallace because they are transitional zones on the landscape across which distinct changes occur in constitution of plant and animal communities. In the xeric landscapes of the central Baja California Peninsula, fan palm (Erythea armata and Washingtonia robusta) oases are small (usually <1 ha) mesophilic islands of structurally complex habitats. We report new records of mesophilic reptiles and amphibians from the adjacent Californian biome in palm groves of the Sonoran region; these highly philopatric species provide evidence of earlier cooler and moister Pleistocene environments. The fan palm oases of the central Baja California Peninsula are natural laboratories for the study of evolutionary processes because they provide unique mesic habitats in a changing desert landscape.

WESTERN HARVEST MOUSE, REITHRODONTOMYS MEGALOTIS (RODENTIA: MURIDAE), ON MAGDALENA ISLAND, MEXICO

Abstract We collected two specimens of Reithrodontomys megalotis on Magdalena Island on the Pacific Ocean side of Baja California Sur. They represent the first insular record of the species in Mexico. These records extend the distribution range of the species about 450 km south of the southernmost record of R. megalotis in Baja California. In addition, three previously unpublished localities in mainland Baja California are reported.

Occurrence of Batrachochytrium dendrobatidis in anurans of the Mediterranean region of Baja California, México

Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and is regarded as one of the most significant threats to global amphibian populations. In México, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the Mediterranean region of the state of Baja California. Using quantitative PCR, Bd was detected in 94 individuals (47.2% of samples) at 25 of the 33 survey localities for 5 native and 1 exotic frog species. The exotic Xenopus laevis was the only species that tested completely negative for Bd. We found that remoteness, distance to agricultural land, and elevation were the best positive predictors of Bd presence. These are the first Bd-positive results for the state of Baja California, and its presence should be regarded as an additional conservation threat to the regions native frog species.

Confirmation of the presence of Microtus californicus in Baja California, México

Abstract. We provide a record and field observations of California vole (Microtus californicus) based on a specimen collected on 5 June 2013 in riparian habitat from Arroyo San Rafael, northwestern Sierra San Pedro Mártir, Baja California, México. The last known record of this species in México was in 1974. This species was suspected to be extirpated from México; however, our recent record confirms its present occurrence in this country.