The Black Aesculapian Snake Zamenis longissimus (Serpentes: Colubridae): characters and possible origin of the subgrisea morphotype

Abstract

New data acquired on the biology of the Aesculapian snake Zamenis longissimus shed light on a widespread specific morphotype in this species: the subgrisea form. Through captive breeding of groups of individuals for several generations, it was established that this morphotype is caused by a recessive mutation. The presence and combination of several traits indicate that this form is not from a single genetic mutation, such as melanoticism or axanthism but from a morphotype more complex than previously considered. The expression of this form in several specimens from different European and Middle Eastern countries suggests that the origin of the morphotype is common and ancient, not random. From genetic analyses, fossil records, and the recent observations of wild individuals, it is probable that this form originated in the Balkan peninsula, where it is more common, and spread to central Europe during the species expansion and recolonization in the late Pleistocene after the last glaciation. Zamenis longissimus could therefore be considered a polymorphic species.