Evolutionary diversification of the limb skeleton in crested newts (Triturus cristatus superspecies, Caudata, Salamandridae)

We explored the interspecific variation patterns in the limb skeleton of four crested newts that underwent an extensive evolutionary diversification. All studied species shared the same basipodial pattern, within which the carpus exhibited much more variation than the tarsus. Morphometric analysis of stylopodium, zeugopodium, and the third metapodial element showed that the species differed in the size of skeletal elements, but they shared common allometric slopes. In comparison to the other crested newts, T dobrogicus appeared as the outlier due to (1) significantly shorter stylopodium and zeugopodium relative to body size and (2) rather different anatomical designs regarding ossification level of the basipodium. Based on these results, it is suggested that the observed T dobrogicus uniqueness originates from allometric heterochrony paralleled by a profound switch in habitat preference.