Description

 Life habit: lichenized; Thallus: crustose to granular; prothallus: absent; isidia, soredia, and goniocysts: absent; cortex: absent or a poorly developed phenocortex with a thin epinecral layer, both without crystals; medulla: usually indiscernable; photobiont: primary one a chlorococcoid green alga, secondary one absent; Ascomata: apothecial, biatorine, with age becoming almost globose, up to c. 1.5 mm wide; disc: ivory-white to yellow to pink to dark red-brown, epruinose, convex; margin: soon excluded, without pigments or containing combinations of a brown (K+ purplish, N+ orange), and a pale yellow to orange (K+ intensifying, N+ intensifying) pigment; exciple: annular, prosoplechtenchymatic, composed of radiating ±branched and anastomosed hyphae with moderately thick, gelatinized, conglutinated walls and cylindrical lumina; terminal cells of the excipular hyphae: not or only slightly enlarged, with moderately gelatinized walls not markedly swelling in K, without crystals; hymenium: colorless below, containing some pigment above but never with crystals, 60-90 µm tall; paraphyses: straight, 1.5-2 µm wide in mid-hymenium, ±conglutinated, unbranched or sparingly branched in upper part, often also somewhat anastomosed; apical cells: swollen or not, never with distinct hoods of pigment; hypothecium: colorless, pale yellow, or brown to red-brown, without crystals and oil droplets, distinctly chondroid; asci: clavate, not markedly thick-walled in upper part, surrounded by a gelatinous, amyloid sheet, with a well-developed, amyloid tholus containing a deeper amyloid, conical zone around the axial body and a widely conical ocular chamber (Biatora-type), often staining faintly, 8-spored; ascospores: hyaline, transversely 1-3septate, fusiform, straight, without perispore and halo; Conidiomata: not known; Secondary metabolites: none detected; Geography: arctic and temperate regions of Europe and North America; Substrate: soil, detritus, and decaying bryophytes.; Notes: Mycobilimbia has, since its resurrection by Hafellner (1984), included three different species groups. One of these groups has recently been transferred to a separate ge M. sabuletorum, and related species (Hafellner and Türk 2001). Remaining in Mycobilimbia are Mycobilimbia s. str, including the type species M. tetramera with relatives, and the "Lecidea hypnorum group", which is distinct from the former on account of its non-septate ascospores, the presence of bluish granules in the hymenium and hypothecium, and its Porpidia-type ascus. The "Lecidea hypnorum group" probably merits rank of a separate genus. Among the Sonoran species, Lecidea holopolia and L. berengeriana belong in this group. The generic description above refers to Mycobilimbia s. str.nus, Myxobilimbia, which includes M. lobulata,