subdivisions line up with transitions between different level III ecoregions. They could have diverged under the indirect allopatric influence of shifting rivers. Rivers would have altered local erosion patterns to bury or expose rocky areas, which salamanders depend on for summer shelter. Despite their overlapping distribution, the two major clades have enough genetic distinction that they may represent two sister species, rather than a single species. Ecology Individuals forage on the forest floor from late October to early May, with activity levels and observations reaching their peak in the winter. Individuals could be readily found sheltering under logs even on dry days in the winter, while no individuals were observed at all during the summer, regardless of the weather. Juveniles stay out slightly longer than adults, but even they disappear by June. The breeding season was probably from January to March according to the biology of collected males. Though oviposition has not been directly observed, the species is an annual breeder and direct developer like other Plethodon species. Females have a clutch size of 3-8 eggs (usually 5 or 6), presumably laid during the summer, which hatch into terrestrial young soon afterwards. This is among the smallest clutch size in any plethodontid, and is probably a consequence of their small adult size. Most growth is achieved during active months (October to May), and the age of sexual maturity is estimated to be around 2 years on average. Individuals are often assumed to take shelter underground during the inhospitable summer, and drift fence experiments have helped to reveal exactly how this movement occurs. As warmer months approach, salamanders travel on humid nights towards rock outcrops and crevasses, which allow access to cooler and moister underground refuge from summer heat. These cooler areas would serve as dens for brooding females and newly-hatched juveniles, as well as other sheltering individuals. Deep naturally-occurring refuges are particularly important to this species, which is among the southernmost members of the genus Plethodon and probably has poor burrowing ability due to its small and fragile build. A few more northern plethodontids with a similar body shape (like the eastern red-backed salamander, P. cinereus) are also known to move into burrows for summer aestivation. P. cinereus relies mostly on soil disturbances and burrows created by other animals, which may be too warm and shallow to be an effective solution for Webster's salamander. Small individuals feed primarily on mites