NECROPHAGOUS BEETLES (COLEOPTERA: SCARABAEOIDEA AND SILPHIDAE) ALONG AN ELEVATIONAL GRADIENT FROM CERRO DE GARCIA, JALISCO, MEXICO

The present work describes the patterns of richness and abundance along an elevational gradient, complemented with an annotated checklist of necrophagous beetle species (Scarabaeidae, Trogidae, Geotrupidae, and Silphidae) collected in Cerro de Garcia, Jalisco. The site is located southwest of Lake Chapala and in the western region of the Trans-Mexican Volcanic Belt. Specimens were collected each month during one year of sampling. Seven sites were surveyed with elevations ranging from 1,600 to 2,700 m. At each site, two carrion traps baited with squid were used and additional specimens were collected directly from cow dung during July. A total of 4,320 specimens were collected, belonging to 26 species within four families. Silphidae were the most abundant beetle family, comprising 64% of the total beetle abundance. In the superfamily Scarabaeoidea, Scarabaeidae were the most abundant at 31% of the total abundance and also the most diverse. Geotrupidae and Trogidae represented 5% of the total abundance. The results show that richness and diversity indices decrease as the elevation increases. However, abundance values were highest at an intermediate elevation of 2,000 m. The diversity of richness and abundance along the elevational gradient showed greatest spatial heterogeneity in the distribution of dung beetle species at 2,000 m where sites with species with affinities to tropical and high mountain environments overlapped.