Bacidina brandii (Coppins & van den Boom) M. Hauck & V. Wirth
Herzogia, 23, 1: 16, 2010. Basionym: Bacidia brandii Coppins & van den Boom - Lichenologist, 34: 328, 2002
Description: Thallus crustose, episubstratic, of scattered to usually confluent, convex, 0.1-0.4 mm wide, greenish grey to pale brown-grey, ecorticate areoles. Apothecia numerous, biatorine, dispersed to crowded, sessile and adpressed, 0.05-0.5 mm across, with a flat to usually convex, at first pale red-brown, then dark red-brown disc and a paler margin. Proper exciple 24-40 μm wide, hyaline, the cell lumina 3-5 μm in the middle part, widening towards apical edge to 7(-10) μm, sometimes excipular hyphae thinner, 1.5-2 μm, but at least most outer row cells swollen and up to 7(-10) μm thick; epithecium colourless; hymenium colourless, 30-40 μm high; paraphyses few, simple, 1.5-2 μm thick at mid-level (in K), the apical cells clavate-capitate, up to 5 μm wide; hypothecium dark reddish brown, K+ dull fuscous brown. Asci 8-spored, clavate to cylindrical-clavate, the apical dome K/I+ dark blue with a pale, conical-pointed apical cushion (axial mass) never penetrating through the entire d-layer, the wall K/I-, but the thin outer gel K/I+ blue, Bacidia-type. Ascospores (0-)1-3-septate, hyaline, acicular, straight, or mostly slightly curved, 24-31 x 0.8-1.3 μm. Pycnidia rare, whitish, more or less immersed, the wall hyaline. Conidia thread-like, curved, 23-30 x 0-8-1 μm, appearing narrowly 3-septate in lactophenol-cotton blue. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-. Chemistry: thallus probably without lichen substances; apothecia with the Arnoldiana-brown pigment in the hypothecium.
Note: a species with a wide distribution in Central Europe, from the British Isles to Russia, also known from Alaska, growing on subacid bark, rotten wood and rusted metal. To be looked for in Italy.