Geographic variation in Incilius occidentalis (Anura: Bufonidae), an endemic toad from Mexico, with a redescription of the species and delimitation of the type locality

Abstract

A taxonomic revision of the populations referable to the wide ranging species Incilius occidentalis was conducted based on 10 morphometric variables and other external morphological traits. Thirty three populations were geographically defined from more than 220 locality records of the species. A brief summary of the nomenclatural history of this species is presented and the external morphological variation is analyzed. Incilius occidentalis is here redescribed on the basis of comparisons with the 3 specimens housed at the Old Collection of the Torino Museum, and over 850 specimens held at several herpetological collections. Statistical analysis using principal components analysis (PCA) demonstrated that SVL concentrates the main part of the variance observed in these populations. No distinguishable populations were detected on the basis of morphometric differences using the Tukey HSD analysis. Body proportions are fairly similar between the 33 populations defined, suggesting the idea that the typical body shape of the bufonid genera is also perceived in this species. The species I. occidentalis is fully redescribed, 1 lectotype and 2 paralectotypes are designated. The geographic range of this species is accurately defined and the type locality is restricted to the City of Guanajuato, and surroundings, Mexico.