Comparative Cranial Osteology of Hydrophis schistosus Daudin, 1803 and Hydrophis platurus (Linnaeus, 1766) (Elapidae: Hydrophiinae)
Keywords:Basisphenoid process, Cranial morphology, Hydrophiinae, Piscivorous, Hydrophis
The viviparous sea snakes of the subfamily Hydrophiinae are morphologically and ecologically diverse and distributed throughout the Indo-Pacific. Earlier works on the cranial morphology of the Hydrophiinae were mostly on the description of teeth-bearing bones and schematic diagrams of skulls. The present study aims to provide a detailed description of the cranium and mandibular structure of two commonly distributed sea snake species in India, namely Hydrophis schistosus and H. platurus. This study analyzes the variations in the cranial morphology between these two species using thirty-two allometric characters. This study also reveals that various components of the skull vary in shape as compared to their terrestrial Elapid cousins. On comparison among these two species, it was found that there are considerable morphological variations in the length of major bones like ectopterygoid, frontal, mandible, maxilla, nasal, parietal, premaxilla, pterygoid and quadrate. In addition, structural variation in the frontal, parietal, premaxillary, and basisphenoid bones along with variation in all the teeth-bearing structures including maxilla, palatine, pterygoid and dentine have also been noticed. Further, the basisphenoid process which is present in H. schistosus and absent in H. platurus which may have a functional role associated with the dietary specialization in the former species to capture the catfishes that constitute their major prey.