Phylogenetic Relationships And Feeding Behavior Of Neotropical Snail-eating Snakes (Dipsadinae, Dipsadini)

Abstract

The snake subfamily Dipsadinae contains more than 350 ecologically diverse species in about 32 genera. Members of the tribe Dipsadini are gastropod specialists, and many possess a suite of adaptations for eating snails. I tested chemosensory prey preference in Dipsas, Sibon and Tropidodipsas species. Additionally, I described the feeding behavior of Tropidodipsas annuliferus, T. philippii and Sibon nebulatus. All snakes preferred gastropod prey. Tropidodipsas philippii also showed strong interest in the earthworm scent and subsequently consumed earthworms. Snakes snagged or wedged snail shells on surface irregularities and extracted snails using muscular contractions of the body, representing an undescribed feeding behavior in vertebrates. I used two mitochondrial (cyt-b and ND4) and two nuclear (NT3 and DNAH3) genes totaling 3241 bp to test relationships among the Dipsadini and among dipsadine genera. Geophis is deeply nested within the Dipsadini. I synonymize Sibynomorphus with Dipsas and three Sibon species with S. dimidiatus. I identify five new genera and 11 dipsadine tribes: Diaphorolepini, Dipsadini, Leptodeirini, Nothopsini, Tribe nov. 1 (Adelphicos + Cryophis), Tribe nov. 2 (Atractus), Tribe nov. 3 ((Amastridium + Chapinophis) + (Trimetopon (Coniophanes (Rhadinaea + Urotheca)))), Tribe nov. 4 (Chersodromus + Ninia), Tribe nov. 5 (Enuliophis + Enulius), Tribe nov. 6 (Hydromorphus + Tretanorhinus), Tribe nov. 7 (Rhadinophanes + Tantalophis). The tree topology supports the hypothesis that dipsadine snakes experienced a dietary shift and adaptive radiation.