Although Webster’s Salamanders, Plethodon websteri Highton (1979), and Southern Zigzag Salamanders, P. ventralis Highton (1997), are highly divergent phylogenetically, they are so similar morphologically that no method for distinguishing them has been published other than by genetic analysis. The range of Plethodon websteri extends farther south than that of P. ventralis; however, there is broad latitudinal overlap, and they are known to co-occur in at least two counties in Alabama, USA. The lack of a convenient method of species identification has hindered ecological studies and conservation assessments. The purpose of this study was to develop a method that can be used to distinguish the species visually in the field based on differences in ventral pigmentation.
Results/Conclusions
We captured salamanders of each species, photographed them in the field, and took tail tips for species identification by mtDNA sequencing. We sampled P. ventralis from five populations in three counties in Alabama and from seven populations in one county in Mississippi. Plethodon websteri were sampled from 12 populations in seven counties in Alabama, 17 populations in nine counties in Mississippi, two populations in two counties in Georgia, and one population each from South Carolina and Louisiana. Ventral photographs were scored for the presence or absence of several features including a midline iridophore stripe along the chest or belly, and a light zone along the midline of the tail. Using these features, we produced a key that permitted identification of most individuals. Although genetic analysis remains the gold standard for distinguishing P. websteri and P. ventralis, species-specific differences in ventral pigmentation patterns permit preliminary visual identification in the field, which should facilitate research on the ecology and conservation status of these cryptic species.