COMPARATIVE MORPHOLOGY OF THE MAXILLARY TEETH AND FANGS OF COLUBRID SNAKES

MATÍAS N. SÁNCHEZ; CARLOS A. LÓPEZ; MARÍA E. BENÍTEZ; MARÍA L. BUSTOS; GLADYS P. TEIBLER; MARÍA E. PEICHOTO

Foz do Iguaçu

Congreso; XXXI Reunião Anual da Federação de Sociedades de Biologia Experimental; 2016

Federação de Sociedades de Biologia Experimental

Introduction: Several advanced snakes (Caenophidia) inject venom to subdue their prey using a sophisticated venom-delivery system. This consists in two specialized glands, each closely associated with a modified tooth - specialized for venom conduction -, the fang. According to the presence or absence of fangs and their position in maxilla, snakes can be divided into three groups: snakes with no fangs (aglyphous), front-fanged snakes (proteroglyphous and solenoglyphous) and rear-fanged snakes (opisthoglyphous). Many ?colubrid? snakes are rear-fanged snakes. Although there is much information about maxillae of front-fanged snakes, less is known about those from rear-fanged snakes, mainly because of the enormous amount of ?colubrids? around the world.Objectives: Taking into account that the driving forces underlying the evolutionary adaptations in the snake venom delivery system still remains unknown, the aim of this study was to describe the morphology and features of the maxillary teeth and fangs of some colubrid snakes from Argentina.Methods:Five species of snakes belonging to the family Colubridae and having Duvernoy´s Glands (DG) were studied herein: Oxyrhopus guibei, Erythrolamprus aesculapii and Erythrolamprus poecilogyrus with terrestrial habits; Philodryas olfersii and Leptophis ahaetulla marginatus with arboreal habits. The specimens were from the Herpetological Collection of the National Institute of Tropical Medicine, Puerto Iguazú (Misiones, Argentina). The two maxillary bones were dissected out of the individuals, allowed to dry and mounted on a stub, using double-sided tape, with teeth pointing upwards. Specimens were sputter-coated with gold using a Denton Vacuum Desk II, and then examined using a JEOL 5800LV scanning electron microscope (SEM) at an acceleration voltage of 15 kV.Results: The maxillae of the five species showed enlarged posterior tooth with or without groove. This adaptive feature constitute an important factor because enhances the conduction of DG secretion into inflicted bite wounds. In the case of P. olfersii, the fang is deeply grooved, but it is just slightly depressed in O. guibei and E. aesculapii. In fangs of L. ahaetulla marginatus and E. poecilogyrus, grooves are absent but they exhibit blade-like appearance. The different structural and functional features of these venom-delivery systems suggest that they represent different solutions to environmental challenges of prey capture and/or defense.Conclusion:This study provides new findings about the different dentition morphology among rear-fanged snakes and contributes to the understanding of the evolutionary mechanisms acting on the venom-delivery system and their varied functions and biological roles.