Notes on the cranium of the paedomorphic Eurycea rathbuni (STEJNEGER, 1896) (Urodela: Plethodontidae) with special regard to the dentition

Abstract

We illustrate the skull, the lower jaw, and especially the dentition of the highly specialized troglobitic salamander Eurycea rathbuni using cleared and stained specimens, scanning electron microscopy, and a few histological sections. Arrangement of the skeletal elements corresponds to earlier descriptions. Dentigerous bones are the fused premaxillae, the vomeres, the palatinal portions of the palatopterygoid in the upper jaw and palate, and the dentaries and coronoids in the lower jaw. Each bone bears a single row of teeth, which are especially numerous and small on the premaxillae and dentaries. Generally, teeth are monocuspid and most are recurved. The dividing zones are unrecognisable to slightly distinct, but do not reach the fully transformed state. Absence or only traces of pedicellation, monocuspidity and an enlarged base are typical for urodele teeth in a relative early stage of development.