Diet, size, and pholidosis of Crotalus ericsmithi, and new prey items for Crotalus lannomi (Serpentes: Viperidae)

Abstract

Crotalus ericsmithi and Crotalus lannomi are two of the least studied rattlesnake species endemic to Mexico. We describe the diet and morphologicalvariation of C. ericsmithi and report novel prey items for C. lannomi based on data from recent field encounters. The diet of C. ericsmithi consists mainly of mammals, followed by reptiles, with no detected ontogenetic shift or sexual differences in prey type. This first detailed study of the diet of C. ericsmithi adds six new prey species. Crotalus ericsmithi does not show sexual dimorphism in snout–vent length and total length, but males have significantly longer tails and smaller head widths and lengths than females. It also exhibits sexual dimorphism in number of subcaudal scales, dorsal body blotches, and tail bands (higher in males), and in midbody dorsal scale rows and intercanthals (higher in females). The mental scale extends posteriorly, preventing contact between the first pair of infralabials in 75% of the specimens examined; therefore, this scale should not be considered a reliable diagnostic character. We identified two new rodent prey items in the diet of wild C. lannomi. Our sample sizes are relatively small, reflecting the rarity of these species, so they must be interpreted with caution. Further research into the natural history of the elusive Long-tailed rattlesnakes and their kin are necessary to enhance conservation efforts.