Protoblastenia pseudocompressa Pykälä & Myllys, 2025

Pykälä, Juha & Myllys, Leena, 2025, Unexpected species richness of the lichen genus Protoblastenia (Lecanorales, Psoraceae) in Finland, MycoKeys 124, pp. 193-226 : 193-226

Protoblastenia pseudocompressa Pykälä & Myllys sp. nov.

Fig. 4 A

Diagnosis.

Differs from P. compressa in often having convex apothecia.

Type.

Finland • Koillismaa, Salla, Onkamo, Latvarova SW , clear-cut heath forest, on calcareous boulder, 258 m a. s. l., 66°42'N, 28°055'E, 9 August 2021, J. Pykälä 58457 ( H 9250942 – holotype, UPS – isotype, GenBank accession number: PV 766696 ) .

Description.

Thallus white to grey, continuous, rimose (usually) to areolate, rarely endolithic, ca. 0–0.15 mm thick, K-, C-, UV- to UV + bluish-white, algal cells 6–12 μm. Apothecia orange-yellow to orange, 0.2–0.7 mm, plane to strongly convex, 1 / 4–1 - immersed in thallus or rock to superficial, sometimes leaving shallow pits; ca. 20–120 apothecia / cm 2. Epihymenium yellow-brown to orange-brown, 12–18 μm thick, K + violet. Hymenium 50–60 μm thick. Hypothecium colourless to pale yellow, rarely pink (in one specimen), ca. 50–120 μm thick. Paraphyses ca. 1.5–2.5 μm thick, sparsely branched and anastomosing. Ascospores 0 - septate, (6.8 –) 9.1–10.6 – 12.1 (– 13.0) × (4.2 –) 4.7–5.5 – 6.2 (– 8.0) μm (n = 51).

Habitat and distribution.

Protoblastenia pseudocompressa has been verified by ITS only from the Oulanka area (parishes Kuusamo and Salla) in NE Finland. However, a morphologically similar specimen was found in the neighbouring biogeographical Province of Kainuu. The species cannot be identified with certainty by morphology only and it is likely that more populations occur in the Oulanka area. It mainly grows on dolomite rock outcrops ( one specimen was collected from a dolomite boulder) and may prefer half-shady habitats. Typical companion species are Acarospora glaucocarpa , Clauzadea monticola , Farnoldia jurana , Hymenelia prevostii (Duby) Kremp. , H. rhodopis , Lathagrium fuscovirens , Placynthium nigrum , Thelidium declivum , Verrucaria deversa , V. muralis , V. kuusamoensis Pykälä, Kantelinen & Myllys and V. subtilis .

Etymology.

The name refers to the close relationship in ITS and morphological similarity to P. compressa .

Notes.

Protoblastenia pseudocompressa is closely related to P. compressa and the two species are also morphologically similar. Protoblastenia pseudocompressa has, on average, slightly smaller spores than P. compressa , but there is a wide overlap. Furthermore, P. pseudocompressa specimens with plane to slightly convex apothecia may be confused with P. compressa . However, the apothecia of P. pseudocompressa are often convex, while the apothecia of P. compressa are always plane to slightly convex. Based on the distribution of sequenced specimens, the two species are geographically well separated. Protoblastenia pseudocompressa specimens with convex apothecia may also be confused with P. borealis , which, however, often has a thicker hymenium.

Other specimens examined.

Finland • Koillismaa, Kuusamo, Oulanka National Park, Pikkukönkäänkuru , dolomite rock outcrop, small W-facing wall, 175 m a. s. l., 66°21'N, 29°19'E, 8. 8. 2009, J. Pykälä 35901 ( H) ; • Salla, Oulanka National Park, 400 m N of Savilampi, bank of River Savinajoki , dolomite rock outcrop, on NW-facing wall, 178 m a. s. l., 66°25'N, 29°10'E, 13. 8. 2009, J. Pykälä 36325 ( H) ; • Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N , SW-slope, Pinus sylvestris - dominated forest, small dolomite rock outcrop, on SW-facing wall, scarce, 175 m a. s. l., 66°22'N, 29°19'E, 6. 8. 2010, J. Pykälä 39367 ( H) ; • Kuusamo, Oulanka National Park, Kiutaköngäs, bank of Oulankajoki River , by the rapids, calciferous (dolomite) schistose rock outcrop, on rather flat rock, 150 m a. s. l., 66°22'N, 29°20'E, 10. 8. 2010, J. Pykälä 39693 ( H) ; • Kuusamo, Oulanka, Putaanoja, 500 m W-NW of Hautala , dolomite rock outcrop, on E-facing wall, scarce, 232 m a. s. l., 66°22'N, 29°25'E, 15. 8. 2010, J. Pykälä 39987 ( H) .

Figures

Figure 4. A. Protoblastenia pseudocompressa (holotype); B. P. pseudoterricola (holotype); C. P. remota (holotype); D. P. rikkinenii (holotype). Scale bars: 0.5 mm.