Continental versus Mediterranean European Whip Snake Hierophis viridiflavus: a morphometric approach

Hierophis viridiflavus, a wide distributed European colubrid, has been subjected to taxonomic studies, with particular reference to morphological aspects of subspecific variation. Other aspects of biology, ecology, and ethology are still anecdotal. Because of its wide distribution and extreme abundance around the Tyrrhenian and Ligurian Seas, it could be of great interest to test if any eventual geographic variation of morphological features could be related to different ecological adaptations (i.e.: dietary habits, reproductive strategies). We focused our attention on the occurence of: a) larger body sized Hierophis viridiflavus in peninsular and continental (i.e. the Po valley area, pre-Alpine areas) Italy, b) smaller body sized Hierophis viridiflavus on small Mediterranean islands if compared to those with larger body size on large Mediterranean islands and mainland areas. The main set of results clearly indicate a strong differentiation among the considered populations: Hierophis viridiflavus of continental and north peninsular Italy do not differ from the populations of the Ligurian and Tyrrhenian islands. On islands, the Whip snakes of Corsica and of small islands in the Tuscan Archipelago display a significantly high number of ventrals while in the Sardinian and Sicilian populations a lower number of ventrals has been found; the lowest number of ventrals is displayed by the Sicilian population. These morphological differences suggest the occurrence of separate evolutionary patterns. Therefore, as a consequence we propose to assign the Sardinian populations to Hierophis viridiflavus sardus (Suckow, 1798) and the Sicilian populations to Hierophis viridiflavus xanthurus (Rafinesque Schmaltz, 1810).