Protoblastenia rikkinenii 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 rikkinenii Pykälä & Myllys sp. nov.

Fig. 4 D

Diagnosis.

Differs from P. fennoarctica in always having convex to strongly convex apothecia and from P. saanaensis and P. timdalii in having sparsely occurring apothecia and a thick hypothecium.

Type.

Finland • Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N , fell, dolomite rock outcrop, on dolomite pebbles, 735 m a. s. l., 69°12'N, 21°26'E, 2 August 2011, J. Pykälä 43252 ( H 9250944 – holotype, GenBank accession number: PV 766700 ) .

Description.

Thallus white, grey to pale brown, rimose to areolate, ca. 0.05–0.2 mm thick, K-, C-, UV-, algal cells 5–9 μm. Apothecia yellow-orange, 0.3–0.8 mm, convex to strongly convex, 1 / 2 - immersed to superficial; ca. 20–40 apothecia / cm 2. Epihymenium dirty yellow to orange-yellow, 12–18 μm thick, K + violet. Hymenium 50–70 μm thick. Hypothecium pale yellow, ca. 80–300 μm thick. Paraphyses ca. 2–2.5 μm thick, apex slightly thickened to 3 μm thick. Ascospores 0 - septate, (7.4 –) 8.5–9.6 – 10.7 (– 12.6) × (4.4 –) 4.7–5.1 – 5.5 (– 6.3) μm (n = 52).

Habitat and distribution.

The species occurs on dolomite rock outcrops, dolomite stone and dolomite pebbles on the fells. It may prefer sun-exposed sites. Companion species include Halecania alpivaga (Th. Fr.) M. Mayrhofer , Hymenelia heteromorpha (Kremp.) Lutzoni , H. prevostii , H. rhodopis , Lecidea polycocca Sommerf. , Polyblastia sp. , Rhizocarpon petraeum , Thelidium huuskonenii and Verrucaria lapponica Pykälä. One GenBank sequence ( KY 266981 ) originates from northern Norway.

Etymology.

The name is in honour of Prof Jouko Rikkinen (Helsinki) for his innovative work on various fields of lichenology.

Notes.

The species is related to P. fennoarctica , which often has more densely occurring, often plane and / or yellow apothecia. However, an ITS sequence may be needed for unambiguous identification of specimens. Protoblastenia saanaensis and P. timdalii have a thinner hypothecium and more densely occurring apothecia. Protoblastenia calvella has more densely occurring apothecia and slightly larger spores.

Other specimens examined.

Finland • Enontekiön Lappi, Enontekiö, Kilpisjärvi, Saana Nature Reserve, W-part , fell, dolomite rock outcrop, on W-facing wall, 700 m a. s. l., 69°03'N, 20°48'E, 9. 8. 2011, J. Pykälä 43910 ( H) ; • Enontekiö, Kilpisjärvi, Saana Nature Reserve , fell, steep SW-slope, dolomite rock outcrop, beneath SW-facing wall, on dolomite stone, 840 m a. s. l., 69°02'N, 20°50'E, 14. 8. 2011, J. Pykälä 44387 ( 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.