Ecological Distribution of the Salamanders Gyrinophilus and Pseudotriton in a Southern Appalachian Watershed

The stream-type larval forms of the hemidactyliine plethodontid salamanders Gyrinophilus porphyriticus, Pseudotriton montanus, and P. ruber show subtle interspecific variation in pigmentation and body proportions. I tested the hypothesis that morphological divergence is correlated with adaptive diversification in habitat selection by evaluating the ecological distribution and habitat affinities of larvae of these species in the Chattooga River watershed of the southern Blue Ridge Physiographic Province. Pseudotriton montanus was observed in a single habitat, a bottomland swamp in the floodplain of a third-order stream. Both G. porphyriticus and P. ruber showed an affinity for springs, although the latter had a wider distribution in higher-order streams and small ponds. In springs, larvae of G. porphyriticus showed a greater preference for rheocrenes and a proclivity for burrowing in the coarse substrates of these habitats; in contrast, larvae of P. ruber were more common in limnocrenes and helocrenes, which have finer substrates, and were usually observed among decaying leaves or beneath surface rocks and logs. The habitat associations and behaviors documented herein reinforce earlier interpretations of the adaptive significance of morphometric variation among larvae of the three species.