Reproduction in the Sonoran shovelnose snake (Chionactis palarostris) and the western shovelnose snake (Chionactis occipitalis) (Serpentes: Colubridae)

Reproductive tissue was examined from 20 museum specimens of Chionactis palarostris and 48 specimens of Chionactis occipitalis from Arizona and Sonora, Mexico. Males of C. palarostris and C. occipitalis undergo testicular cycles in which spermiogenesis occurs in spring-early summer. Female reproductive activity takes place during this period. Mean clutch size for C. palarostris (n = 5) was 4.2 ± 0.45 SD, range = 4-5. Clutches recorded from C. occipitalis (2, 3, in this paper) fall within the range previously reported for this species. Reproductive cycles of C. palarostris and C. occipitalis appear similar to that of other fossorial North American desert snakes in which sperm formation coincides with the period of maximum aboveground activity.