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Pertusaria subobducens Nyl.
Family: Pertusariaceae
Pertusaria subobducens image
Stephen Sharnoff  
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus thin, soon superseded by fruiting verrucae which form a thick, knotted mass 1 mm thick, rounded-areolate, convex, shining, yellowish gray, sometimes slightly pruinose, lacking soredia or isidia. Fertile verrucae more or less constricted at base, fusing to form a multiperforate sheet; hypothecium pale; epithecium hyaline or dark, K+ violet; hymenium hyaline to pink; asci cylindrical; spores 2 (rarely 1 or 3), uniseriate longitudinal or oblique, double-walled, outer wall 1-8 μm, inner 4-20 μm, generally smooth, tips usually convex inward, ends laminated, ovoid to ellipsoid, 70-234 x 28-84 μm.

Reactions: cortex K— or K+ weakly yellow, KC— or weakly yellow, UV— or UV+ faintly orange-pink; medulla K+ yellow, C—, KC—, P+ yellow turning orange.

Contents: 2,7-dichlorolichexanthone, stictic acid, constictic acid, and three unknowns.

This species grows on humus and plant debris, and over moss and soil in the Arctic, but also on hardwoods in the south of the range. It is not found in Europe but occurs in Asia and North America, where it ranges south in New England in the eastern mountains, and is also found in the Great Lakes region. This species is very close to P. coriacea, differing mainly in the chemistry and the color reaction of the epithecium.