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Verrucaria aspecta Breuss
Family: Verrucariaceae
Verrucaria aspecta image
Othmar Breuss  
Thallus: cracked-areolate, up to 0.3 mm thick, c. 2 cm wide, fissures ± acute, of varying width, prothallus lacking areoles: subangular, plane, 0.6-1.1 mm wide, basally slightly constricted, with steep pale sides surface: greenish gray to gray, smooth or somewhat uneven, dull anatomy: upper cortex: indiscernible, not overlain by an epinecral layer; algal layer: distributed throughout most of the upper 3/4 of the thallus, with algal cells 7-12 µm in diam.; mycobiont portion: paraplectenchymatous throughout, composed of cells 4-7 µm in diam.; alga-free medulla: present as the lowermost thin layer, slightly brown, large parts of the whole thallus interpspersed with fine granules or crystals (in polarized light) Perithecia: fully immersed, their apices flat, up to 0.3 mm across in surface view, level with surface of areoles, round or somewhat irregular in outline; exciple: subglobose or somewhat deplanate, 0.3-0.4 mm wide, pale when young, soon darkening; involucrellum: appressed to exciple, extending to its base-level and slightly incurved beneath, laterally 60-90 µm thick; periphyses 35-45 µm long, 3-4 µm thick, densely septate (cells 3-5 µm long) asci: clavate, 70-90 x 22-26 µm, 8-spored ascospores: hyaline, simple, ellipsoid , 19-23 x 8-10 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on non-calcareous rock in exposed situation World and Sonoran distribution: known only from the type locality on Santa Rosa Island, California. Notes: Diagnostic for Verrucaria aspecta is its deeply areolate thallus with flat-topped, completely immersed perithecia giving an Aspicilia-like appearence, medium-sized ascospores and short-celled rather stout periphyses. The similar Verrucaria lecanoroides, described from Italy (Servít 1952) has larger spores (26-31 x 11-13 µm). In Verrucaria maculicarpa the perithecia may also appear as rather broad spots in surface view, but this species has furrowed-rugose areoles, thinner involucrella, and larger spores.