The evolution of the melanistic colour in the Alpine Salamander Salamandra atra as revealed by a new subspecies from the Venetian Prealps

In order to reconstruct the evolution of the body colour within the Salamandra atra group, a phylogenetic analysis of the mitochondrial DNA D-loop sequence was performed on seven populations of this group, including all three chromatically different forms and all known nominal subspecies. Also included were four outgroup species. Three major mitochondrial lineages were found within S. atra: (i) the invariably yellow-patched S. a. aurorae lineage from the Altopiano dei Sette Comuni (Venetian Prealps); (ii) a genetically distinct lineage represented by a population from the Pasubio massif (Venetian Prealps), in which the yellow patches were either limited or completely lacking; (iii) a lineage comprising all fully melanistic populations from the Alps to the Dinarides, which were assigned to S. a. atra and also included the nominal S. a. prenjensis. Different phylogenetical reconstruction methods and statistical tests supported the hypothesis that the lineage of S. a. aurorae was the sister group to both remaining lineages of S. atra. Within these latter lineages, S. a. pasubiensis emerged as the sister group to all populations of the S. a. atra lineage. This phylogenetic reconstruction suggests that the yellow-patched colour is the ancestral condition in S. atra and the evolutionary transition to fully melanistic colour occurred probably through an intermediate reduction in the extension of the patches. Therefore, the fully melanistic colour of S. lanzai, which is probably not strictly related to S. atra, has an independent origin. The population from the Pasubio massif is here described as Salamandra atra pasubiensis n. subsp.