Comparative anatomy and homology of jaw adductor muscles of some South Asian colubroid snakes (Serpentes: Colubroidea)

We studied jaw adductor muscles in eighteen species of South Asian colubroid snakes and presented a comparative account of their anatomy. The deepest layer of external adductor appears to be a composite of aductor mandibulae externus medialis and profundus fibres and caenophidians are characterized by an attenuation of the former muscle which may be correlated with the development of a derived type of mandible. Our observations further suggest that, though highly reduced, fibres homologous to adductor mandibulae externus medialis may be present in at least some colubroids with a bodenaponeurosis. Some hitherto unreported features pertaining to levator anguli oris and pterygomandibularis of some studied elapid, colubrine colubrid and ahaetuliine colubrid genera are also described.