Reproductive Biology and Population Structure of the Western Red-Backed Salamander, Plethodon vehiculum (Cooper)

Abstract

Certain aspects of the life history of Plethodon vehiculum from Benton and Lincoln Cos., Oregon, were studied. Mating occurs primarily from November through January with oviposition in the spring. The number of yolky ovarian ova is a function of body size; the mean for all sizes was was 10.4/female. Incubation is in the summer, with hatching in the fall at 13 to 15 mm SVL. Growth rates for both sexes are about 10mm SVL/year for the first 3 years. Both sexes mature between their second and third years: males at 42 mm SVL and females at 44 mm SVL. Females have a biennial gonadal cycle as has been described for other species of Plethodon, and males have annual cycle. Spermatogenesis begins in the spring and culminates in the fall. Mature females are larger (mean SVL = 49.1 mm) than mature males (mean SVL -45.7 mm). In general, P. vehiculum, a western plethodon, has a life history similar to that of eastern small and eastern large plethodons. * * * The genus Plethodon can be divided into 3 natural groups (Grobman, 1944; Highton 1962a): the eastern large plethodons, the eastern small plethodons, and the western plethodons. Highton (1956, 1962b) and Pope and Pope (1949) described the reproductive cycle of the slimy salamander, Plethodon glutinosus, an eastern large plethodon; and Sayler (1966) studied the reproductive ecology of the red-backed salamander, Plethodon cinereus, an eastern small plethodon. Werner (1971) provided further notes on P. cinereus, and the reproductive biology of a second eastern small plethodon, the northern ravine salamander, Plethodon richmondi richmondi, was studied by Angle (1969). The geographically isolated Jemez Mountains salamander, Plethodon neomexicanus, is thought to be related to the eastern small plathodons