Author: Beat Schätti

Abstract

The Holarctic racers (Coluber s.l.) do not represent a holophyletic genus. The unifying characters of Old and New World species are mainly those of external morphology and represent convergence. Differences in hemipenes and osteological characters (basisphenoid, vertebrae) necessitate generic distinction of Old and New World species and thus the restriction of Coluber s.s. to Nearctic forms. The results, moreover, do not justify the separation of the genus Masticophis Baird and Girard from the single Nearctic species, C. constrictor Linnaeus. Sixteen of twenty Palearctic species can be assigned to three species groups most typically represented by C. jugularis, C. rhodorachis, and C. hippocrepis, respectively. Changing or proposing new generic names for these groups must be avoided until the evolutionary polarity of characters is known for the Oriental and Ethiopian forms.

In: Amphibia-Reptilia
In: Amphibia-Reptilia