Rests while contacting conspecifics. Sometimes co-occurs with P. carolinianus (Webb 1950).
May be found crawling on rocks and smooth-barked trees at night or in the rain (Hubricht 1985).
External: Cream to gray body with tiny black spots; seven black or black-brown chevrons along length of dorsum, with a longitudinal gray stripe on mid-dorsum; black tentacles; edge of foot and tail tip gray or black; translucent white sole (Binney 1874; Webb 1950; Burch 1962; Fairbanks 1990).
Internal: Ribbed jaw (Binney, 1874); relatively long apical chamber in penis; penis containing 7-9 pustulose longitudinal pilasters that extend between the apical chamber and base; atrium with pale orange glandular tissue around its lower section; two lobes, each with 2-3 folds dividing it, inside upper atrium (Fairbanks 1990).
Differs from Philomycus: more narrow-bodied, ribbed jaw, translucent sole (Webb 1950). Similar to M. ragsdalei, but penis, penis apical chamber lengths, and vas deferens longer in M. wetherbyi, and atrial lobes different (Fairbanks 1990).
Extended: 108 mm long (Webb 1950).
E Tennessee and SE Kentucky (Hubricht 1985).
Sandstone cliffs, river bluffs, and ravines (Hubricht 1985; Fairbanks 1990); takes shelter in rotten logs and clefts or holes in sandstone, including deeper holes that might serve for over-wintering (Webb 1950).
Feeds on lichen (Webb 1950).