Swinscowia glabra (A. Massal.) S.H. Jiang, Lücking & Sérus. comb. nov.
MycoBank number: MB 836413; Index Fungorum number: IF 836413; Facesoffungi number: FoF 08907.
Bas.: Sagedia glabra A. Massal., Ric. Auton. Lich. Crost.: 161 (1852); Spermatodium glabrum (A. Massal.) Trevis., Conspect. Verruc.: 11 (1860); Porina glabra (A. Massal.) Zahlbr., Cat. Lich. Univers. 1: 382 (1922); Arthopyrenia glabra (A. Massal.) J. Nowak & Tobol., Flora Polska: 1117 (1975); Strigula glabra (A. Massal.) V. Wirth, Flechtenflora: 531 (1980).
= Pyrenula netrospora Nägeli, Flecht. Europ.: no. 461 (1857); Spermatodium netrosporum (Nägeli) Trevis., Conspect. Verruc.: 11 (1860); Sagedia netrospora (Nägeli) Anzi, Comm. Soc. Crittog. Ital. 1(3): 162 (1862); Arthopyrenia netrospora (Nägeli) Müll. Arg., Mém. Soc. Phys. Hist. Nat. Genève 16(2): 429 (1862); Verrucaria netrospora (Nägeli) Nyl., Jahresber. St. Gall. Naturw. Ges.: 504 (1882); Porina netrospora (Nägeli) Lettau, Hedwigia 52: 104 (1912).
= Sagedia candida Anzi, Comm. Soc. Crittog. Ital. 1(3): 162 (1862).
Notes: Swinscowia glabra forms a species complex with S.albicascens and S. stigmatella, all three growing on bark and producing chiefly 7-septate ascospores with overlapping size ranges. There seem to be no discernable differences between the Australasian S. albicascens and the European S. glabra. Roux and Sérusiaux (2004) do not discuss S. albicascens in the context of S. glabra, and McCarthy (2009) does not mention S. glabra in the discussion of S. albicascens, although he did synonymize Verrucaria indutula with the latter. We keep S. glabra and S. albicascens separate for the time being, as macroconidia have not yet been reported for the latter and might turn out to provide a diagnostic difference, although we consider this unlikely. Roux & Sérusiaux (2004) discuss the similarity between S. glabra and S. stigmatella and keep both separate on account of slightly different ascospore length (22–26 µm in S. glabra vs. 26–36 µm in S. stigmatella) and differences in substrate (smooth bark in S. glabra and rough bark in S. stigmatella). Harris (1995) gives ascospore length for North American material of S. stigmatella as 24–42 µm, whereas McCarthy (2009) cites 16–32 µm for Australasian S. albicascens. McCarthy (1993) reported S. stigmatella as saxicolous from Australia but later corrected these records to S. decipiens (McCarthy 2009). Thus, the taxonomic treatments for corticolous taxa with 7-septate ascospores are inconsistent between North America, Europe, and Australasia, using one name in North America (stigmatella), two in Europe (glabra, stigmatella), and one but a different name in Australasia (albicascens). This problem is aggravated by the notion that the type of Lichen stigmatellus Ach. grows on smooth bark and apparently fits the concept of S. glabra by Roux & Sérusiaux (2004). This requires a critical revision of the available material and a reassessment of the types to properly name the taxa distinguished in this complex.