Verrucaria subdevergens Pykaelae & Myllys sp. nov. Fig. 2F

Diagnosis.

Differing from V. devergens by longer involucrellum, morphologically difficult to separate from V. kuusamoensis, but the sequence divergence in ITS 5.4-6.0%.

Holotype.

Finland, Koillismaa, Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, dolomite rock outcrop, on gentle NE-slope, 165 m alt., 66°24'N, 29°11'E, 25 Aug 2011, J. Pykälä 45109 (holotype: H9205097, GenBank accession number: MT229783).

Description.

Prothallus absent. Thallus white, grey, ochraceous or pale greyish-brown, endolithic to thinly epilithic, continuous to irregularly rimose, in one specimen contiguous conspecific thalli separated by a dark line. Perithecia 0.21-0.42 mm, 1/2-3/4-immersed, leaving shallow to deep pits in the rock, often surrounded by a thallus collar, in one specimen, thalline covered except apex, thalline cover 8-20 mm thick; 80-120 perithecia/cm2. Ostiole inconspicuous, tiny, pale to dark, plane or depressed, ca. 20-40 mm wide. Involucrellum covering half of the exciple or to the exciple base, in few perithecia may envelope the exciple, 30-80 mm thick, in one specimen, often apically thickened to 50-70 mm thick, appressed to the exciple. Exciple 0.21-0.34 mm in diam., wall blackish-brown, ca. 15-25 mm thick. Periphysoids ca. 25-50 × 1.5-2 mm. Asci 82-94 × 27-33 mm, 8-spored. Ascospores 0-septate, (23.0-)25.4-28.2-31.0(-34.9) × (11.2-)12.0-13.0-13.9(-15.2) mm (n = 83), perispore 1-1.5 mm thick.

Habitat and distribution.

All three finds are from the Oulanka area in NE Finland where the species grows on dolomite rock outcrops and on a dolomite boulder.

Etymology.

The species is close to V. devergens .

Other specimens examined.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N, Pinus sylvestris -herb-rich forest, small dolomite rock outcrop, on small S-facing wall, 165 m alt., 66°22'N, 29°19'E, 3 Aug 2010, J. Pykälä 39128 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, Picea abies -dominated herb-rich forest, dolomite rock outcrop, NE-slope, on dolomite boulder, 174 m alt., 66°24'N, 29°11'E, 20 Aug 2011, J. Pykälä 44550 (H).

Notes.

This species is close to V. devergens and V. karelica, based on the ITS phylogeny. It differs from these species in a longer involucrellum mainly exceeding half of the exciple. Morphologically, V. subdevergens is most difficult to separate from V. kuusamoensis, which tends to have shorter periphysoids and the thallus is more often white.