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Lichenostigma dimelaenae Calat. & Hafellner
Family: Lichenotheliaceae
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Hyphal strands: absent Ascomata: superficial, black, frequently arising between the host areoles or towards their margin, confluent in dense elongate to irregular groups of numerous ascomata of about 0.5-1 mm long and 0.2-0.5 mm wide, cushion-like, compressed among them, rounded or ±irregular, 70-140 µm wide, 40-80 µm tall disc: flat or convex; lower part of ascomata: flat or sometimes irregular, then usually with some prominent cells penetrating into the host thallus internal structure: wall of the external cells: dark brown, with a granular pigment, pale brown in the internal ones, cells 3-6 µm in diam centrum: I+ pale red, K/I+ intense blue asci: subglobose, 27-30 x 20-27 µm, 8-spored ascospores: hyaline initially but soon brown, 1-septate, occasionally submuriform, 3-celled, with an angular septum in the upper hemispore, ±ellipsoid and not constricted at the septum when young, broadly obovate and constricted at the septum 11-15 x 6.5-11 µm, when mature, not halonate, with a granular surface when mature. Host: on the thallus of Dimelaena oreina World and Sonoran distribution: northern Arizona. Notes: The ascomata, not connected to superficial hyphal strands and forming dense groups, are characteristic of Lichenostigma dimelaenae. Although the habit of L. dimelaenae resembles some Lichenothelia species, in the absence of interascal filaments, in having a hymenium-like layer (in L. dimelaenae the asci develop between pseudoparenchyma of the stromatic ascomata) and macroconidia characteristic of Lichenothelia, it is considered to be best accommodated in Lichenostigma.