Thelidium auruntii (A. Massal.) Kremp., Denkschr. Kgl. Bayer. Bot. Ges. 2(4): 248 (1861).

Pykaelae, Juha, Kantelinen, Annina & Myllys, Leena, 2023, Taxonomy of Thelidium auruntii and T. incavatum complexes (lichenized Ascomycota, Verrucariales) in Finland, MycoKeys 96, pp. 1-23 : 1

Thelidium auruntii (A. Massal.) Kremp., Denkschr. Kgl. Bayer. Bot. Ges. 2(4): 248 (1861).

Verrucaria auruntii A. Massal., Symmict. Lich. 77. (1855). Basionym.

Type.

[ Italy] ad saxa dolomitica in opp. Auronzo ( Col della Favola ) (VER!) .

Description.

Prothallus not visible. Thallus pale brownish grey to pale greyish brown, rarely medium brown, continuous to rimose, rarely areolate, up to 0.2 mm thick, in one specimen surrounded by one dark line, algal cells c. 6-11 μm. Perithecia 0.21-0.38 mm in diam., 1/2-3/4-immersed, not leaving pits to leaving shallow pits; c. 60-160 perithecia / cm2. Ostiole dark, plane to depressed, c. 20-50 μm wide, ostiolar depression up to 120 μm wide. Involucrellum apical, exceeding half of the exciple to rarely to the exciple base level, 30-80 μm thick, appressed to the exciple or to clearly diverging from it. Exciple 0.16-0.29 mm, wall pale to dark brown (usually brown), c. 17-20 μm thick. Periphysoids c. 20-40(-50) × 1.5-2 μm. Asci c. 62-72 × 26-32 μm, 8-spored. Ascospores 0-1-septate, (20.3-)24.5-26.9-29.2(-32.1) × (9.2-)10.6-11.5-12.4(-13.3) μm (n = 86).

Habitat and distribution.

The species occurs in northern Finland in Enontekiö, Kuusamo and Salla parishes on dolomite rock outcrops, boulders, stones and pebbles. Several collections come from the calcareous fells of Saana and Toskalharji in Enontekiö. In the biogeographical province Koillismaa, the species is very rare, and it has been confirmed only from two localities (one in Kuusamo and one in Salla). The species grows mostly on dry sun-exposed calcareous rocks. However, some localities on river and brook shores are probably periodically submerged.

Notes.

The Finnish specimens are included in T. auruntii , because no clear morphological differences between the type of T. auruntii and the Finnish specimens were found. However, the type has slightly shorter spores: 20-26 × 10-14 μm. The type of T. auruntii is from the Dolomites in northern Italy. It is possible that T. auruntii is an arctic-alpine species. Sequences from the Dolomites are needed to confirm whether the Finnish specimens are conspecific with T. auruntii .

Pykälä (2007) reported the species as T. pyrenophorum (Ach.) Körb. from Finland, but the specimens differ morphologically from T. pyrenophorum (type: Helvetia, H-ACH-685!). The type of T. pyrenophorum differs in larger perithecia: 0.35-0.7 mm. According to our ITS phylogeny, the two species are rather closely related (Fig. 1 ) if the GenBank specimen of T. pyrenophorum from Sweden is correctly identified. Thelidium methorium (Nyl.) Hellb. is characterised by large perithecia, thick involucrellum, larger spores (mean 34 × 14 μm) and occurrence on siliceous rocks ( Thüs and Nascimbene 2008; Orange 2013). Thelidium pertusatii (Garov.) Jatta resembles T. methorium but has a very thick involucrellum (110-170 μm thick) ( Thüs and Nascimbene 2008). The differences between closely related T. pseudoauruntii and T. sallaense are discussed below.

Several other Thelidium species are morphologically rather similar to T. auruntii . Thelidium incinctum (Vain.) Vain. (Finland, Kuusamo, Porontimajärvi, 12.8.1867, F. Sileń (H!, H-NYL6941, syntypes)) differs in thicker involucrellum (70-80 μm thick), larger spores (25-38 × 12-15 μm) and occurrence on siliceous rock. It is only known from the type collection. Thelidium bubulcae (A.Massal.) Arnold described from Italy (ad saxa ipocretacea (Preapura) M. Bolca (M. Colle), 1854, A.Massalongo (VER!); Veneto; ad saxa arenacea oppidi Bolca (M. Colle) in prov. Veronensi Massalongo, Anzi: Lich. Rar. Veneti 136 (UPS-L-686416!, syntypes?) is rather similar to T. auruntii but may possibly differ by shorter, apical involucrellum and areolate thallus. Thelidium lacromense Zschacke ([Croatia] ins. Lacroma: An frei liegenden Gestein, c. 10 m, Kalk, 11.9.1907, A.Latzel (PRM-858048!, syntype)) is morphologically similar to T. auruntii , but the type locality is close to sea level in Croatia and thus not likely to belong to the same species as the Finnish material of T. auruntii . Thelidium athallinum Servít (Slovakia, Vysoké Tatry, monte Tokárna, supra saxa conglom., 1100-1200 m, 1925, Suza (PRM-858571!, syntype)) differs in thicker involucrellum (c. 80-100 μm thick).

Other specimens examined.

Finland, Koillismaa, Salla, Oulanka National Park , 400 m N of Savilampi , shore of river Savinajoki , dolomite rock outcrop, on NE-slope, 177 m a.s.l, 66°25'N, 29°10'E, 13 August 2009, J. Pykälä 36339 (H); Kuusamo, Oulanka National Park , Mataraniemi, shore of Oulankajoki river , treeless stony river shore, on dolomite stones, 145 m a.s.l, 66°22'N, 29°20'E, 26 August 2011, J. Pykälä 45171 (H); Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, dried old brook bottom, stony bottom, on dolomite pebbles, 707 m a.s.l., 69°11'N, 21°26'E, 3 August 2011, J. Pykälä 43414 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, brook, W-shore, dolomite rock, outcrop, on N-slope, 710 m a.s.l, 69°11'N, 21°26'E, 3 August 2011, J. Pykälä 43446 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, brook, W-shore, dolomite rock outcrop, on dolomite stones, 710 m a.s.l, 69°11'N, 21°26'E, 3 August 2011, J. Pykälä 43470 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, gentle SE-slope, alpine grassland, on dolomite boulder, 705 m a.s.l, 69°11'N, 21°26'E, 3 August 2011, J. Pykälä 43829 (H); Enontekiö, Kilpisjärvi, Saana, nature reserve, W-part, fell, dolomite rock outcrop, on SW-facing wall, 695 m a.s.l, 69°03'N, 20°48'E, 9 August 2011, J. Pykälä 43905 (H) .

Figures

Figure 1. Phylogenetic relationships of the studied species. Strict consensus based on ITS data set with bootstrap values (> 50 %) at nodes. New species described in this study are indicated in bold.