Protoblastenia calvella Kainz & Rambold, Bibl. Lichenol. 88: 290 (2004)

Description.

Thallus white to whitish-grey, rimose to areolate, areoles 0.2–0.5 mm, ca. 0.02–0.2 mm thick, K-, C-, UV-, algal cells 5–8 μm. Apothecia orange-yellow to orange, 0.3–0.6 mm, strongly convex, superficial, not leaving pits to leaving shallow pits, K + violet; ca. 40–100 apothecia / cm 2. Epihymenium dark orange-brown, 12–15 μm thick, K + violet. Hymenium 80–100 μm thick. Hypothecium colourless to pale yellow, ca. 100–180 μm thick. Paraphyses ca. 2–2.5 μm thick, apex slightly thickened, often branching. Ascospores 0 - septate, (7.6 –) 9.4–10.7 – 12.0 (– 12.7) × (4.4 –) 5.2–5.9 – 6.7 (– 7.8) μm (n = 29).

Habitat and distribution.

Only two specimens are known from northern Finland (Pykälä 2023). The habitats are sun-exposed calcareous and calciferous rock outcrops where the species grows on rock or on pebbles. The species is associated with Enchylium polycarpon (Hoffm.) Otálora, P. M. Jørg. & Wedin and Rhizocarpon petraeum .

Notes.

In the ITS phylogeny, the P. calvella specimens are divided into three strongly-supported lineages: the first one includes three specimens collected in Austria, Germany and Sweden; the second group includes two Finnish specimens and the third group consists of specimens collected in Croatia and Germany (Fig. 1). More material is needed to determine whether P. calvella represents several species. Protoblastenia calvella is a cryptic species which cannot be identified without molecular data (Wirth et al. 2013). Older apothecia are often brown-orange to dark red-brown (Svensson et al. 2024), but such colouration was not observed in the Finnish specimens. It may be confused with several other Protoblastenia species. A few specimens of P. borealis have a thick hypothecium and / or hymenium and thus resemble the Finnish specimens of P. calvella . The Finnish specimens of P. rupestris have a thinner hymenium and hypothecium compared to P. calvella . Furthermore, the apothecia tend to be predominantly orange, while in P. calvella, they are orange yellow. Protoblastenia ekmanii may differ in having darker orange apothecia. Protoblastenia fennoarctica can be rather similar to P. calvella, but its apothecia vary from plane to strongly convex and its hymenium is thinner (ca. 50–80 μm thick).

Specimens examined.

• Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskalpahta, fell, dolomite rock outcrop, on steep SW-slope, 820 m a. s. l., 69°11'N, 21°30'E, 4. 8. 2011, J. Pykälä 43503 (H) ; • Koillismaa, Kuusamo, Juuma, Niskakoski, river bank, calciferous (dolomite) schistose rock outcrop, on pebbles, 224 m a. s. l., 66°16'N, 29°24'E, 22. 8. 2011, J. Pykälä 44807 (H) .