Slideshow image
Pertusaria octomela (Norman) Erichsen
Family: Pertusariaceae
Pertusaria octomela image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus thin, whitish or yellowish white, smooth, continuous to warty, shiny, epruinose, lacking isidia or soredia. Fertile verrucae with bases constricted, almost spherical, to 0.8 mm broad; ostiole slightly sunken to papillate, dark; margin also often dark. Apothecia 1 (rarely 2 or 3) per verruca; hypothecium hyaline; epithecium dark, K+ violet; hymenium hyaline to pink; asci cylindrical; spores 8 (rarely 6) uniseriate, longitudinal or oblique in orientation, double-walled, outer wall 1-4 ¡xm, inner 1-6 μm, tips usually convex inward, ellipsoid to fusiform, 28-98 x 11-53 μm.

Reactions: cortex K—, C—, KC—, P—, UV—; medulla K+ yellow turning red, C—, KC—, P+ yellow turning orange.

Contents: norstictic acid, connorstictic acid and scant stictic acid, constictic acid and an unknown.

This species grows on moss, humus, soil, and the remains of plants, and occasionally on old wood. It is circumpolar arctic in North America, with a station south in the Rocky Mountains in Colorado.