Vertebral anomalies in a natural population of Taricha granulosa (Caudata: Salamandridae)

Developmental plasticity, a common pattern in lissamphibian evolution, results in numerous alternative morphologies among species and also within populations. In the present study, a natural population of the salamander Taricha granulosa (Salamandridae) was examined to detect variation in the vertebral count and to identify potential deformities of their vertebral column. The number of trunk vertebrae varied between 11 and 13 and we recorded 58 individuals with 69 anomalous vertebral elements. These anomalies range from congenital malformations (block vertebrae, unilateral bars, hemivertebrae), extra ossifications in the haemal region, to posttraumatic pathologies. Most osseous pathologies were encountered in the caudal region of the axial skeleton. Our data suggest a high frequency of vertebral malformations in salamanders; however, the identification of the exact causes remains challenging.