Slideshow image
Verrucaria falcata Breuss
Family: Verrucariaceae
Verrucaria falcata image
Othmar Breuss  
Life habit: appearing lichenicolous, on or between areoles of Verrucaria maculicarpa Thallus: areolate, 0.15-0.20 mm thick, very small, forming scattered groups of 2-7 areoles each areoles: subangular or ±round, flat or slightly convex, 0.2-0.4 mm wide, contiguous to ±separate, typically circling halfway around a perithecium surface: brown, dull anatomy: upper cortex: composed of a single layer of cells, with or without a thin, amorphous epinecral layer; algal layer: paraplectenchymatous, 50-70 µm thick, with algal cells 7-10 µm in diam.; medulla: subparaplectenchymatous, composed of ±round cells 4-6 µm in diam., with slightly brown lowermost parts Perithecia: emerging from between areoles or distinctly marginally on isolated areole with areole circling halfway around it; exciple: globose, c. 0.2 mm wide, brown; involucrellum: contiguous with exciple, extending down to exciple-base level and in-curved beneath, 30-40 µm thick laterally, thinning at base; periphyses 20-25 µm long, simple asci: clavate, 50-55 x 17-20 µm, 8-spored ascospores: hyaline, simple, ellipsoid to tear-shaped, 15-16 x 6-7 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, over conglomerate, also on Verrucaria maculicarpa World and Sonoran distribution: known only from the type locality. Notes: Tear-shaped spores are also characteristic for Verrucaria dacryodes, but this latter species is non-parasitic, has larger thalli with a dark basal layer, and thicker involucrella. Verrucaria fraudulosa is also non-parasitic, has a complete involucrellum and oblong to narrowly ellipsoid spores.