Slideshow image
Placopsis cribellans (Nyl.) Rasanen
Family: Trapeliaceae
[Lecanora cribellans Nyl.]
Placopsis cribellans image
Laurens Sparrius  
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus forming small lobate thalli, marginal lobes divided and crenulate with rounded ends, flattened, centrally chinky or areolate with areolae to 1.8 mm broad; cream-colored or whitish or becoming light olive-brownish, the surface closely pitted with pockmark depressions from the loss of isidia or with entire globose isidia; lacking soredia or hypothallus; cephalodia sessile, scattered, flattened or depressed-convex, radially folded and chinky, pale yellowish or flesh-colored. Apothecia scattered, constricted at base, to 1.3 mm broad; margin persistent, prominent, entire to subcrenulate; proper exciple thin, sometimes visible, flesh-colored; disk flat or slightly concave, flesh-colored to rose-red or red-brown, bare or whitish pruinose; hypothecium hyaline; epihymenium yellowish; hymenium 90-180 µm, hyaline; paraphyses slightly thicker at tips; spores ellipsoid, 12-16.5 x 6-9 µm. Conidia filiform, slightly curved, 21-29 µn.

Reactions: cortex K+ faint yellow, C+ red, P+ roseate; medulla K+ yellowish or K—, C+ red, P—.

Contents: unreported but probably gyro-phoric acid.

The species grows on rocks and pebbles, sometimes on sandy soil. It is distributed on the Pacific Ocean shores in both the Northern and Southern Hemispheres, with a disjunct occurrence on Tristan da Cunha in the Atlantic. In Alaska it is reported from Unalaska and from Port Clarence on the SSeward Peninsula. In British Columbia it occurs near Bella Coola and at the Kitimat Arm.