Analisi comparativa tra le sottospecie italiane di Natrix natrix mediante morfometria geometrica

Natrix natrix is a snake distributed all over the Palearctic region, but its subspecific systematics is still debated. Four subspecies are considered valid in geographic Italy: natrix in the north-east, helvetica in the remaining peninsula, cetti in Sardinia, and corsa in Corse. Other two subspecies were hypothesised to occur in, respectively, Calabria (calabra) and Sicily (sicula), but their validity should be verified. A geometric morphometric analysis was conducted to assess the differences in head shape among snakes coming from all the Italian subspecies. Our results confirmed the differences among the four accepted taxa and highlighted a different homogeneous clade from southern Italy and Sicily. Sardinian and Corsican grass snakes showed some affinities and both appeared to be distinctly separated by continental specimens. Further analyses are necessary to understand phylogeographic relations among the taxa and to assess the effect of sexual dimorphism on shape differences.