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Mycobilimbia spp.
Family: Lecideaceae
Mycobilimbia image
Stephen Sharnoff  
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,
Species within Rocky Mountain National Park