Verrucaria subtilis Müll. Arg.
Flora, 57, 34: 536, 1874.
Synonyms: Amphoridium subtile (Müll. Arg.) Servít; Verrucaria hypophaea (J. Steiner & Zahlbr.) Servít; Verrucaria rupestris var. hypophaea J. Steiner & Zahlbr.
Distribution:
Description: Thallus crustose, very thinly episubstratic or hemiendosubstratic, white, pale grey or pale grey-brown, continuous to rimose, up to 0.1 mm thick, without a distinct prothallus. Perithecia black, 40-160/cm2, 0.15-0.35(-0.44) mm across, (1/2-)3/4 to rarely fully immersed, leaving shallow to deep pits in the rock, sometimes the projecting part covered by a thin thalline layer in lower part. Involucrellum apical or dimidiate, 30-70(-80) µm thick, appressed to exciple or diverging from it in lower part; exciple 0.16-0.33 mm across, the wall 18-30 µm thick, usually dark brown to black (rarely paler); hamathecium of branched periphysoids measuring c. 20-40(-50) x (1-)1.5-2.5(-3) µm; hymenial gel hemiamyloid, I+ red (I+ blue at very low concentrations of I), K/I+ blue. Asci 8-spored, clavate, I-, fissitunicate, the wall thickened above, with an ocular chamber, dehiscent by extrusion of an endotunica to form a delicate rostrum, Verrucaria-type, 58-84 x 22-28 µm. Ascospores 1-celled, hyaline, ellipsoid, (20-)23-28(-31) x (8.3-)10-12(-12.8) µm, surrounded by a thin perispore at least when young. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.Note: a perhaps long-forgotten species described from Switzerland on dolomite and for a long time known from the type collection only. According to Pykälä & al. (2020), however, it is amongst the most common species of Verrucaria on calcareous rocks in southern Finland. To be looked for in Italy.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Poorly known taxon in need of further study
Predictive model
Zschacke, H. (1934) Epigloeaceae, Verrucariaceae und Dermatocarpaceae. In: Dr. L. Rabenhorst‘s Kryptogamen-Flora, Band 9, Abt. 1, Teil 1. Akademische Verlagsgesellschaft, Leipzig, 695 pp. - Public Domain
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Poorly known taxon in need of further study
Predictive model
