Skull osteology of Vipera walser (Squamata, Viperidae): Description, variability, ontogeny, and diagnostic characters in comparison to other Italian vipers.

摘要: Vipera walser is the most recently recognized European viper. This rare species endemic to a small area in Piedmont Alps of Italy, but its closest relatives are found among Caucasian viper species. In order provide starting point for phylogenetic and biogeographic investigation based on osteology, including fossils remains, we analyzed four specimens V. compared them with other Italian Based these specimens, improved diagnosis provided first evaluation intraspecific variability ontogenetic variation. The skull subject significant variation, likely related ontogeny some cases (i.e., development parietal crest, basioccipital process, shape posterior margin parabasisphenoid, quadrate). studied material, it possible distinguish from vipers by occipital crest supraoccipital, which posteriorly directed, whereas laterally directed osteological diagnosibility provides further support validity as distinct berus.