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Miriquidica scotopholis (Tuck.) B. D. Ryan & Timdal (redirected from: Miriquidica mexicana)
Family: Lecanoraceae
[Lecanora scotopholis (Tuck.) Timdal,  more]
Miriquidica scotopholis image
Thallus: +crustose, areolate-squamulose, extensive (up to 3 cm in diam.); prothallus: vestigial, black areoles: peltate (narrowed into a short stalk below), appressed to more often broadly ascending, 0.4-1 mm in diam., contiguous to imbricate, partly confluent, mostly convex, folded and often funnel-shaped upper surface: dark red-brown or brown-black (appearing black without lens), +shiny, the edges swollen and smooth, green-black to gray, esorediate upper cortex: hyaline below and dark brown above, medulla: spottily gray-brown, c. 25 µm thick, without granules; hyphae: 3.5 µm in diam., thin-walled; algal layer: c. 50 µm thick, continuous; algae: 10-15 µm in diam. lower surface: green-black near the edge, red-black otherwise lower cortex: dark red-brown, 30-50 µm thick, with unoriented, dark hyphae with irregularly shaped cells 3-5 µm across Apothecia: +common, usually scattered, 0.5-1 mm in diam., closely and broadly sessile, laminal on the squamules, lecanorine when young, later appearing lecideine disc: dark brown to almost black, paler and redder when wet, plane, soon becoming strongly convex, +shiny margin: pale gray, soon +excluded, without a parathecial ring amphithecium: initially present, with an algal layer filling up most of the margin, without a developed medulla marginally, corticate; cortex: 15-25 µm thick, the outer 5-10 µm dark brown to greenish brown, K+ olive, with fine dark granules (insoluble in K and N), the inner part hyaline exciple: pale to medium brown towards outside, hyaline inside epihymenium: pale or medium brown, inspersed with fine dark granules (insoluble in K and N), 5-15 µm thick hymenium: hyaline, I+ blue, 4045 µm tall; paraphyses: distinct and easily freed in water, flexuous, simple to often branched and anastomosing, c. 1.5 µm wide, thin-walled, the septa distinct in water, the lower cells 5-10 µm long, constricted at the septa, the apical cells brown-capped, 3-4 µm wide; subhymenium: hyaline, indistinctly delimited from hypothecium hypothecium: hyaline to pale yellow centrally, 200-300 µm thick, with very dense, unoriented, thin-walled hyphae 1.5-2 µm wide asci: clavate, c. 40 x 10 µm; outer wall layer: I+ dark blue, inner wall layer I+ pale blue; tholus: I+ dark blue, with very distinct ocular chamber and narrow axial mass narrowing towards the tip, 8-spored ascospores: hyaline, simple, oblong-ellipsoid to ovoid, 8-11 x (3-)4-5 µm Pycnidia: sessile on margins of the areoles conidia: filiform, 15-35 x 1 µm Spot tests: thallus and apothecia K-, C-, KC-, P- Secondary metabolites: miriquidic acid (major)and five unknown substances (Timdal, 1984, based on the holotype in FH). Substrate and ecology: on siliceous rocks (sandstone, quartz) World distribution: western North America (California) Sonoran distribution: expected but not confirmed south of coastal, central California. Notes: Miriquidica scotopholis is superficially similar to various members of the Lecidea atrobrunnea group (which can be distinguished by its strongly coherent paraphyses, green-black to blue-black epihymenium, and different ascus type), Rhizocarpon bolanderi (which has smaller areoles and muriform spores), and Lecania brattiae (which has 1-septate spores). The type collection of Biatora scotopholis (Bolander, s.n., FH!) is from Oakland, California. It consists of several thalli: one with strongly peltate squamules and +convex apothecia; the others have more plane squamules and apothecia. The presence of miriquidic acid, and the color and form of the thallus, suggest that B. scotopholis belongs in Miriquidica, and some species of that genus are superficially similar to it. However, B. scotopholis differs from Miriquidica, as currently circumscribed, as follows: 1) amphithecium well developed at least in young apothecia, and true parathecium poorly developed laterally; 2) hymenial gel I+ blue; 3) paraphyses easily freed; 4) asci with axial mass and ocular chamber well developed and very distinct, and tholus and outer wall both I+ dark blue. The ascus tip of B. scotopholis, as also typical for Miriquidica, appears somewhat intermediate between the Bacidia-type and the Lecanora-type, and the thallus chemistry and morphology are also different from that of other species of Lecanora. The species differs from Psorula, in which it was placed by Schneider (1979), in a number of features, including having filiform conidia, a different ascus type, brown epihymenium, loose paraphyses, pale hypothecium, and a different chemistry. The best solution is to treat it as a Miriquidica species.