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Stereocaulon intermedium (Savicz) H. Magn.
Family: Stereocaulaceae
Stereocaulon intermedium image
Stephen Sharnoff  
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Primary thallus disappearing; pseudopodetia densely caespitose, attached to rocks, 5-8 cm tall, 1-3 mm thick, with scattered long branches at acute angles, whitish, thinly tomen-tose; phyllocladia evenly distributed on the po-detia, verrucose to verrucose-coralloid, 0.15-0.18 mm thick; cephalodia inconspicuous among the phyllocladia, to 1 mm, irregularly tubercu-late, grayish to brownish gray, containing Nostoc. Central medullary hyphae parallel, very loosely united, pachydermatous, 2-3 µ thick, the exterior of the central cylinder of yellowish, gelatinous, very pachydermatous, hyphae 6-10 µ in diameter, KOH—; cortex of phyllocladia 16-20 µ thick, grayish, hyphae firmly conglutinate, unclear. Apothecia numerous, terminal, margin soon disappearing; disk convex, dark-brown, the margin reflexed and the center dividing into several convex parts; underside of perpendicular, gelatinous, pachydermatous hyphae; hypothecium yellowish, 35-40 µ hymenium 55-65 µ, pale, 1+ blue; paraphyses not firmly con-glutinate, 1.8 µ thick, the apices capitate, 3.5-4.5 yellowish; asci narrowly clavate, 50 x 8-10 µ; spores 6-8, usually 3-septate, rarely 4-5 septate, bacilliform, with one end thicker, the immature spirally twisted in the ascus, 35-48 x 3-3.5 µ. Conidia unknown.

Reactions: K+ yellow, P— .

Contents: atranorin and lobaric acid.

This species grows on stones in areas with masses of rocks. It is a Beringian bilateral radiant, reported from Japan and Kamtchatka in Asia and in Alaska and British Columbia in North America (Lamb 1951) and an unspecified disjunct occurrence in Newfoundland (Lamb 1977).

According to Magnusson it is very like S. grande but differs in the high hymenium, the blunt spores, the free hyphae of the main axis, the thick cortex of the lower side of the apothecium and the thin excipulum with thin hyphae.