Primary thallus disappearing; pseudopodetia white to pale white, tufted, to 4 cm tall; the apices expanded to flattened foliaceous, stiff, wrinkled, the margins crisped and much paler, the bases darkening to black, about 1 mm thick, bare; the underside of the foliose part tomen-tose; cephalodia blackish-brown, verrucose, on the phyllocladia, containing Stigonema. Sections of the phyllocladia 0.4-0.5 mm thick, with a thick gelatinous transparent cortex 50-150 µ thick, the cells indistinct; algal layer continuous, of small 5-10 µ cells; medulla 200-300 µ thick of densely intricate gelatinous hyphae 10-18 µ thick with a 1 µ lumen; lower cortex lacking; the blackish pseudopodetia with the outer 30-40 µ, dark brown, of 4-5 µ hyphae; the interior white, of densely packed con-glutinate pachydermatous hyphae 2-3 µ thick. Apothecia described by Savicz: marginal on the phyllocladia, 0.25-0.5 mm diameter, at first concave, becoming subglobose, reddish brown; paraphyses distinct, the apices darkened; asci 20-30x7-12 µ spores 3-5 septate, acute, 12-22x3.5-4.5 µ. Conidia straight, 4.5-6.5 µ.

Reactions: K+ yellow, P— .

Containing: atranorin and lobaric acid.

This species grows over rocks in the Arctic. It is amphi-Beringian, being known from Japan, eastern Asia, and Alaska where it has been reported from St. Michel (Riddle 1910), the Ogotoruk Creek drainage (Krog 1962), and Mt. Harper in the Yukon district (Krog 1962).

This is extremely similar in morphology to Stereocaulon wrightii Tuck, which differs only in chemistry. S. wrightii contains atranorin and stictic acid and according to Lamb (1977) occurs only in Japan and the USSR, including Arakamchene Island on the west side of Bering Strait.