Morphological variation and new distributional records of Rhadinella dysmica (Serpentes: Dipsadidae), with comparisons with other dark-colored congeners

Small, secretive snakes comprise an important part of the herpetofauna of the Neotropics and yet most species are known from a handful of specimens due to their habits and relatively inaccessible localities. The Mexican endemic Rhadinella dysmica is the westernmost species of the genus and was described based on a single adult female. Herein we provide information on new specimens, including their morphological variation and hemipenial structure, expand the known geographic range for the species, and comment on the morphological similarities of the “dark-colored” species of the genus.