Comprehensive DescriptionRead full entry
For metamorphic adults, the snout-to-vent length is 36-66 mm and total length ranges from 68-116 mm (Hayslett 2003; Semlitsch 1987). Female metamorphic adults are generally larger than male metamorphic adults, with females ranging from 39-72 mm in snout-vent length and males from 41-62 mm in snout-vent length (Raymond and Hardy 1990). Paedomorphic sexually mature adults range in size from about 30-50 mm in snout-to-vent length (Semlitch 1985). The body size of individuals varies across time; it appears that individuals tend to reach a maximum size and then decline with age (Verrell and Krenz 1998). This growth pattern is likely an indication of reproductive senility and asymptotic growth, in contrast to other salamander species that have continuous growth over the lifespan (Raymond and Hardy 1990).
This species is facultatively paedomorphic and both morphs can be found within one population. Adults have disproportionately large and broad heads, small chunky bodies and relatively short tails (Rothermal and Luhring 2005). The body has 10-11 costal grooves (Powell et al. 1998). Four toes are present on each forefoot and five toes on each hindfoot, with hindfeet being disproportionately large (Conant and Collins 1998). Teeth are hooked in shape and are arranged in a single row along both the maxillary and the dentary (Tihen 1958). Paedomorphic adults retain external gills and have a vertically compressed tail. The tail is slightly vertically flattened in metamorphic adults (Conant and Collins 1998).
Metamorphic adults have variable ground body color ranging from black to gray. Some individuals have small blue, white or gray flecks concentrated along the dorsum, sides and tail. The top of the tail often has a white edge, which can be a distinguishing feature if present. Paedomorphic individuals have a gray or brown ground color, often with light flecks that concentrate along the dorsum, tail and sides and distinct yellow ventral stripes. Newly metamorphic individuals will display remnant yellow ventral stripes for a time after metamorphosis. In preservative, the flecked pattern often fades and the coloration is gray to black (Conant and Collins 1998).
Newly hatched larval body sizes can vary from 4.5-8.0 mm in snout-to-vent length. Larvae that did not metamorphose after the breeding season range in snout-to-vent length from about 25-48 mm. External gills are present. Larval coloration is similar to that of paedomorphic adults with a gray or brown ground color, light-colored flecks and yellow ventral stripes. Tail is dorsoventrally flattened with tail fins (Semlitch 1985).