Patterns of phenotypic variation in the European Whip snake, Hierophis viridiflavus (Lacépède, 1789)

The European Whip snake, Hierophis viridiflavus (Lacépède, 1789) is a very variable species when considering external morphology (i.e.: dorsal and colours and markings, head shape, position of main internal organs). Sexual Size Dimorphism (SSD) is much marked than ever described, in almost all the body parameters. Nevertheless, there is again a differential SSD according to geographical areas, with small Mediterranean islands charterised by smaller dimensions. From one side, diet and food preference in the European Whip snake does not diverge from what published, in terms of the species that have been predated; from the other side, large differences have been highlighed in the absolute frequency of the species predated throughout Europe. A maximum preference for mammals in northern France, and a large preference for esotherms (insects, amphibians, reptiles) in central and southern Italy were found. Yearly activity duration is supposed to be determinant in extending the whole available period during which feeding activity occurs. Energetic of diet, directly measured as well estimated from published and original data, has never recorded before in snake species. Our results showed a markedly different pattern, according to average population body size, latitude, and food availability, and were consistent with phenotypic plasticity claimed for many snake species. Phylogeography of the European Whip snake was addressed only in a preliminary way from other scientists, suggesting the presence of two different subspecies in central northern distribution range and in southern Italy. No relevant information has been recorded to explain the presence of two, large, widely distributed, populations of black (melanic, partially melanic) snakes in Italy. I suggest that the melanic populations of Hierophis viridiflavus may represent the inertial pattern of an ancient group of black snakes, more widely distributed than at present times, whose actual populations express also of the normally coloured pattern.