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Verrucaria finkiana Servit
Family: Verrucariaceae
Verrucaria finkiana image
Gerhard Neuwirth  
Thallus: areolate, moderately thick (0.15-0.25 mm), with thin fissures, with or without a thin black basal area, surrounded by a black, partly fimbriate prothallus areoles: plane, polygonal with subacute edges, 0.2-0.5 mm wide, with brown to black side-walls surface: dark gray, gray-brown or brown, smooth, dull anatomy: upper cortex not discernible, only uppermost cell layer brown; algal layer: paraplectenchymatous, composed of cells 4-8 µm in diam., with algal cells 6-13 µm in diam., filling most of the thallus Perithecia: sunken within the areoles, one or two per areole, ostiolar region naked, plane or slightly convex; exciple: subglobose to depressed-ovate or broadly pyriform, brownish to black, 0.18-0.22 mm across; involucrellum: reaching down to exciple-base level and slightly incurved beneath, appressed to the exciple throughout, 40-50 µm thick laterally, even in thickness or thickening at base; periphyses 20-25 µm long, simple asci: clavate, 8-spored ascospores: hyaline, simple, narrowly ellipsoid to subfusiform, 18-21 x 7-8 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on both calcareous and acidic rocks World distribution: North America (described from Iowa) Sonoran distribution: Sonora, montane. Notes: Verrucaria nigrofusca comes close to V. finkiana in overall appearance, but differs in hemispherically emergent perithecia and broader spores.