Cetradonia J.-C. Wei & Ahti (=Gymnoderma Nyl.) (Cetradoniaceae)
Cetradonia is represented by a single species, endemic to the southern Appalachians: C. linearis (Fed E, S2 G2). The species was formerly referred to Gymnoderma s.l. and listed under its combination in that genus: Gymnoderma lineare (Yoshimura & Sharp 1968).
Basic lichen habits
Federally listed taxon—
Cetradonia linearis [Gymnoderma lineare] (Fed E, State E | S1 G2)
Habitat. High humidity environments on moist cliffs at high elevations or moist boulders in deep river gorges.
Range. Endemic to the southern Appalachians.
Notes: A squamulose lichen with an unknown photobiont that is suspected to be a species of Trebouxia, a green alga (Brodo et al. 2001).
Identification.“Grows in dense colonies of narrow (.04 inch) straps that are blue-grey on the upper surface and generally shiny-white on the lower surface: near the base they grade to black (the similar species of squamulose Cladonia are never blackened toward the base). Fruiting bodies are borne at the tips of the straps & are black (similar Cladonia species have brown or red fruiting bodies).”(USFWS)