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Verrucaria calkinsiana Servit
Family: Verrucariaceae
Verrucaria calkinsiana image
Gerhard Neuwirth  
Thallus: indistinct, up to 0.15 mm thick, continuous and sparsely fissured to verruculose with convex "areoles" 0.2-0.3 mm wide surface: grayish white to pale tawny, dull anatomy: subparaplectenchymatous, composed of cells 5-9 µm in diam. with small interspersed substrate particles, with irregularly distributed algal cells 7-13 µm in diam. Perithecia: half immersed to almost superficial, hemispherical emergent with their bases immersed in the thallus which is slightly raised in their vicinity; exciple: 0.2-0.3 mm wide, subglobose or somewhat deplanated, brown; involucrellum: appressed, covering at least two thirds of the exciple, mostly extending to exciple base level, lateral up to 100 µm thick ; periphyses 20-30 µm long, thin asci: clavate, 70-80 x 15-25 µm, 8-spored ascospores: hyaline, simple, ellipsoid , (18-)20-25 x 8-12 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on sandstone in more or less sheltered places from lower to montane level, also found on volcanic rock in a seasonal streambed World distribution: mainly eastern North America Sonoran distribution: few collections from Arizona and southern California. Notes: The difference against the European Verrucaria gudbrandsdalensis is not clear-cut; the perithecia of V. calkinsiana are somewhat smaller and have thicker involucrella. Another European species, Verrucaria cincta, has the same type of involucrellum as V. calkinsiana but smaller spores (17-21 x 7-8 µm). Verrucaria amylacea has smaller spores and thinner involucrella. In Verrucaria muralis the involucrellum is also thinner and rarely reaches more than half-way down the exciple.
Verrucaria calkinsiana image
Troy McMullin  
Verrucaria calkinsiana image
Othmar Breuss  
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image
Verrucaria calkinsiana image