On the maxillary dentition of the Western whip snake, Hierophis viridiflavus (Lacépède 1789): heterodonty is not opisthoglyphy

The Western whip snake (Hierophis viridiflavus) is a colubroid snake typically considered aglyphous and non-venomous, although this is currently a subject of debate. Indeed, the maxillary dentition of this species has recently been described as opisthoglyphous due to the presence of enlarged rear maxillary teeth, reportedly characterised by prominent grooves and ridges. Aiming to test the actual presence of these structures and provide a clearer characterisation of the maxillary dentition of the species, we analysed 17 dry-prepared and disarticulated H. viridiflavus specimens using both scanning electron and optical microscopy. The imaging confirmed the presence of posterior, enlarged maxillary teeth displaying a distal carina, highlighted by shallow longitudinal inflections on the disto-labial and disto-lingual tooth surfaces. Nonetheless, the analysis revealed the consistent absence of the meso-labially placed groove typical of opisthoglyphous taxa. Based on the results of our study, the maxillary dentition of the Western whip snake is heterodont, specifically opisthomegadont, and is confirmed to be aglyphous.