Verrucaria fuscozonata Pykaelae , Kantelinen & Myllys, 2020

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 fuscozonata Pykaelae, Kantelinen & Myllys sp. nov. Fig. 2D

Diagnosis.

Species characterised by dark lines between contiguous conspecific thalli, pale endolithic thallus, small perithecia leaving shallow to deep pits in the rock, involucrellum reaching the exciple base level and appressed to the exciple, ascospores measuring (21-)24-28(-29) × (10-)11-12(-13) mm.

Holotype.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on SW-facing wall, 160 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36222 (H, GenBank accession number: MT229758).

Description.

Prothallus not seen. Thallus pale grey, endolithic, dark lines between contiguous conspecific thalli, 0.21-0.35 mm wide. Perithecia 0.11-0.26 mm in diam., (1/2-)3/4-immersed, leaving shallow to deep pits in the rock, surrounded by a thallus collar; 120-140 perithecia/cm2. Ostiole inconspicuous, tiny, pale to dark, plane or depressed, ca. 30 mm wide. Involucrellum reaching the exciple base, 50-60 mm thick, appressed to the exciple. Exciple 0.18-0.25 mm in diam., wall dark brown to black. Periphysoids ca. 25-35 × 2-2.5 mm. Asci 8-spored. Ascospores 0-septate, (21.2-)24.5-26.5-28.4(-29.4) × (10.0-)10.9-11.7-12.5(-13.2) mm (n = 36), perispore 1 mm thick.

Habitat and distribution.

The only known specimen is from a dolomite rock on a river shore in north-eastern Finland, in Kuusamo.

Etymology.

The only specimen available is characterised by dark lines between contiguous conspecific thalli.

Notes.

Verrucaria fuscozonata did not group with any of the examined species in the ITS phylogeny. However, it is morphologically rather similar to V. bifurcata , V. kuusamoensis and V. subdevergens . In V. bifurcata , dark lines between contiguous conspecific thalli are absent and the involucrellum usually thinner. In V. kuusamoensis and V. subdevergens , the spores are larger and the perithecia occur less densely. More material is needed to find out whether V. fuscozonata can be unambiguously identified, based on morphology only.

Figures

Figure 2. Habitus of the new Verrucaria species A V. bifurcata (holotype) B V. cavernarum (holotype) C V. difficilis (holotype) D V. fuscozonata (holotype) E V. kuusamoensis (holotype) F V. subdevergens (holotype) G V. vacillans (holotype). Scale bars: 1 mm (A-D), 0.5 mm (E-G).