A quantitative analysis of two scale characters in snakes

Abstract

AbstractWe quantified the effectiveness of two scale characters commonly used to identify snakes: smooth versus keeled dorsal scales and straight versus oblique dorsal scale rows. We examined 169 species of African snakes from close-up photographs of the dorsal scales. We calculated the prominence of keels (if present) along the dorsal scales and the degree of straightness or obliqueness of the dorsal scale rows. We compared our measurements to species descriptions from the literature and looked for overlap of the character states with each other. Our results show a distinct difference between keel prominence for species described as having keeled dorsal scales versus species described as having smooth dorsal scales. Our results also show considerable overlap of straightness or obliqueness between species described as having straight dorsal scale rows versus those described as having oblique dorsal scale rows. Revision of this character would be beneficial.