Variation in number of trunk vertebrae and in count of costal grooves in salamanders of the family Hynobiidae

Ten species from five genera of the family Hynobiidae were studied. The number of trunk vertebrae varied between 14 and 21, and the count of costal grooves ranged from 10 to 15. Both the within-species variation and the within-population variation were recorded in some species. In both kinds the values of the coefficient of variation were quite low. In Salamandrella keyserlingii, the south-eastern samples markedly differed from remaining ones. Among the hynobiids, the genus Onychodactylus (both species) and Batrachuperus mustersi have higher number of vertebrae in the anterior part of trunk (5 and 4, respectively, versus 3), and, thus, demonstrated a distinct position. The relation between the number of trunk vertebrae and the count of costal grooves was studied. The variation in number of trunk vertebrae across urodelan families was discussed.