Protoblastenia minuta 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 minuta Pykälä & Myllys sp. nov.

Fig. 3 C

Diagnosis.

Differs from the other Protoblastenia species with a pale hypothecium in having small apothecia and spores and apothecia which leave pits.

Type.

Finland • Enontekiön Lappi, Enontekiö, Kilpisjärvi, Saana Nature Reserve , E-part, fell, steep SW-slope, dolomite rock outcrop, on S-facing wall, scarce, 715 m a. s. l, 69°02'N, 20°51'E, 12 August 2011, J. Pykälä 44275 ( H 9250941 – holotype, GenBank accession number: PV 766683 ) .

Description.

Thallus ochraceous, endolithic, K-, UV-. Apothecia orange, 0.2–0.4 mm, slightly convex to strongly convex, immersed in rock to superficial, leaving shallow to fairly deep pits; ca. 80 apothecia / cm 2. Epihymenium brown-yellow, 10–12 μm thick, K + violet. Hymenium 45–55 μm thick. Hypothecium colourless to yellow, ca. 70–100 μm thick. Paraphyses ca. 2–3 μm thick, apex not thickened to slightly thickened. Ascospores 0 - septate, (7.3 –) 7.6–7.9 – 8.3 (– 8.8) × (4.1 –) 4.3–4.5 – 4.7 (– 4.8) μm (n = 9).

Habitat and distribution.

Only one specimen has been found on the calcareous Saana fell in NE Finland, on a dolomite rock outcrop. Companion species include Acarospora macrospora (Hepp) A. Massal. ex Bagl. , Enchylium polycarpon , Placynthium asperellum (Ach.) Trevis. s. lat, Romjularia lurida (Ach.) Timdal and Thalloidima alutaceum Anzi.

Etymology.

The name refers to the small size of the apothecia and spores.

Notes.

The species is rather isolated amongst the sequenced species of Protoblastenia (minimum difference from other species over 9 % in ITS). The species has smaller apothecia and spores than most other Protoblastenia species with a pale hypothecium. Furthermore, other Finnish Protoblastenia species do not leave pits or only rarely leave shallow pits. However, only one specimen is known and the species may be expected to be morphologically more variable. More material is needed to evaluate whether the species can be identified by morphology only. Protoblastenia saanaensis has a rimose thallus and the apothecia do not leave pits. Protoblastenia szaferi differs in having larger apothecia and spores (see Hafellner (2006)).

Figures

Figure 3. A. Protoblastenia ekmanii (holotype); B. P. fennoarctica (holotype); C. P. minuta (holotype); D. P. oulankaensis (holotype). Scale bars: 0.5 mm.