Determining sex and life stage of Del Norte salamanders from external cues

Abstract

Life stage determination for many western plethodontids often requires dissection of the specimen. Availability of reliable external measures that could be applied under field conditions would enhance future studies of the genus Plethodon. We examined preserved specimens of the Del Norte Salamander, Plethodon elongatus, taken from 11 sites in northwestern California and southwestern Oregon. During the dissections, we recorded several external body characteristics that could prove useful in determining the life stage and gender of individuals. Identification of life stage is possible by using several external measurements. A discriminant function model including snout vent length, weight, head length, and width correctly classified life stage 92% of the time. A tree-based classification analysis identified snout-vent length as a single variable that could correctly classify life stage 90.2% of the time. We also have identified a sexually dimorphic character for adults, vent pattern and coloration, that can reliably distinguish gender at any time of year.

Citation

Ollivier, Lisa; Welsh Jr, Hartwell H. 2003. Determining sex and life stage of Del Norte salamanders from external cues. Northwestern Naturalist, Vol. 84: 129-134