Verrucaria depressula Servit , nom. nov., Stud. Bot. Cechoslov . 9: 80, 1948

Pykaelae, Juha, Kantelinen, Annina & Myllys, Leena, 2020, Taxonomy of Verrucaria species characterised by large spores, perithecia leaving pits in the rock and a pale thin thallus in Finland, MycoKeys 72, pp. 43-92 : 43

Verrucaria depressula Servit, nom. nov., Stud. Bot. Cechoslov. 9: 80, 1948

= Verrucaria depressa Stenhammar, nom. illeg. non Meyen & Flot., Öfvers. K. Svensk. Vetensk.-Akad. Förhandl. 14: 120, 1857. Type. Sweden, Gotland, Lojsta, Lojsta, in collybus calcareis, 1846-55, C. Stenhammar (H!, two syntypes)

= Verrucaria obscura Th. Fr., nom. illeg. non (Sm. & Sowerby) Borrer 1836, Öfvers. K. Svensk. Vetensk.-Akad. Förhandl. 21: 276, 1865. Type. Sweden, Resmo, C. Stenhammar (UPS!, syntype)

Description.

Prothallus not seen. Thallus grey, pale brown, medium brown or rarely dark brown, with a violet tinge, continuous, rimose or areolate, thallus colour may be variable within specimen, 0.05-0.2(-0.3) mm thick, contiguous conspecific thalli separated by dark lines. Perithecia 0.26-0.52 mm, (1/2-)3/4-immersed, leaving shallow to deep pits in the rock; ca. 60-120 perithecia/cm2. Involucrellum apical, strongly diverging from the exciple (mainly spreading outwards away from the exciple), (40-) 50-90 μm thick. Exciple 0.25-0.4 mm in diameter, pale or dark. Periphysoids ca. 40-60 × (1-)1.5-2 μm. Ascospores 0-septate, (24-)27-35(-45) × 10-18(-20) μm, few spores 1-septate.

Notes.

Based on morphology, V. depressula may belong to the Thelidium group or perhaps more probably be related to V. viridula . The type locality is in Sweden and rather close to Finland, but nevertheless, no specimens fitting with V. depressula have been found from Finland.