Primary thallus: squamulose, persistent; squamules: up to 2.5 mm long and 1 mm wide, ascending, flat to involute, laciniate to irregularly incised, forming crust-like mats, abundantly granular sorediate or coarsely coralloid-lobulate podetia: fairly common but often sparse, 3-15 mm tall, usually dark brown, occasionally gray, without cups, unbranched or very sparingly branched from blunt apices; tips and axils: usually open surface: usually granularly sorediate to squamulose, rugose, sometimes totally or partly corticated Apothecia: fairly common on tips of podetia, rarely sessile on primary squamules, aggregated to form up to 1.5 mm wide glomerules, dark brown ascospores: oblong to fusiform, 7-14 x 2.5-3.5 micro meter Pycnidia: common, on primary or podetial squamules, or at tips of podetia, barrel-formed, constricted at base, with hyaline gelatin conidia: 5-9 x 1 micro meter Spot tests: K+ deep yellow, C & KC- (but + yellow where barbatic acid present), P+ deep yellow, UV- Secondary metabolites: thamnolic acid and (restricted to apothecia) barbatic acid. Habitat and ecology: on rotting pine or oak wood World distribution: Asia, Europe, North America (mainly in the East) and the West Indies Sonoran distribution: Arizona, rare. Notes: This is probably the first correct report of Cladonia parasitica from western North America (although it is common on the east coast of North America). It is easily overlooked because it is commonly without podetia, but it can be recognized by its very dense colonies of tiny, sorediate, finely dissected squamules that react P+ yellow. It grows on old pine or oak logs.