Slideshow image
Mycobilimbia tetramera (De Not.) Vitik., Ahti, Kuusinen, Lommi & T. Ulvinen ex Hafellner & Türk
Family: Lecideaceae
[Bacidia fusca (A. Massal.) Du Rietz,  more]
Mycobilimbia tetramera image
Stephen Sharnoff  
Thallus: crustose, continuous, rather thick surface: gray, coarsely granular or warted Apothecia: single or in groups, 0.4-1.4 mm in diam., at first almost flat but soon becoming convex and ±globose disc: gray-brown, orange-brown, or red-brown margin: concolorous with disc or paler, at first distinct, level with disc, soon excluded and reflexed exciple: irregularly pale yellow (K+ intensifying), pale brown, and red-brown (K+ slowly purplish) in upper part, darkest in parathecial crown, merging with hypothecium pigmentation, fading below, laterally c. 90 µm wide hymenium: colorless below, upper part diffusely pale brown to red-brown (K+ slowly purplish), 60-90 µm tall paraphyses: 1.5-2 µm wide in mid-hymenium; apices: ±clavate or not at all thickened, 2-5 µm wide hypothecium: colorless, pale yellow (K+ intensifying), or partly brown to red-brown (K+ slowly purplish) asci: clavate, Biatora-type, 8-spored ascospores: hyaline, 3-septate, fusiform, straight, 16-28 x 5-8 µm Spot tests: all negative Secondary metabolites: none detected. Habitat and ecology: on bryophytes or soil at c. 3500 m World distribution: arctic and alpine areas as well as temperate mountain forests in North America and Europe Sonoran distribution: known from a single locality on Mount Humphrey in central Arizona. Notes: Mycobilimbia tetramera is very similar to M. carneoalbida and differs from this species mainly in the richer apothecial pigmentation and slightly longer ascospores.
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus crustose, verruculose, ashy glau-cescent, white or brownish glaucescent, more or less continuous. Apothecia 0.7-2.0 mm broad, flattened, brown-black to black, shining, epruinose; margin soon disappearing; disk minutely rugose; exciple pale or red-brown, radiate, the lower side of apothecium appearing as palisade plecten-chymatous; hypothecium hyaline to light brown, not as dark brown as in Micarea melaena; epihymenium pale or brown; hymenium hyaline to brownish, outer part brownish, 90-120 ¡xm, 1+ blue turning purplish; paraphyses 1-2 μm, tips thickened, not branched, gelatinous, very coherent; asci clavate; spores biseriate, ellipsoid with acute tips, 3-septate, 16-34 x 6-8 μm.

Reactions: K—, C—, P—; when margin is reddish, KOH turns it violet.

This species grows on soil, humus, old wood, and occasionally bark. It is circumpolar arctic to boreal.