Calonarius subcorrosus Niskanen & Liimat., sp. nov.
Index Fungorum number: IF 900304; Mycobank number: MB 900304; Facesoffungi number: FoF 14861; Figs. 1e, 2e, 3
Etymology – The species is close to C. calojanthinus (C. corrosus ss auct.).
Holotype – K-M 001434093.
Pileus 3–6 cm in diam, hemispherical, then low convex to almost plane, ochre brown from the centre with small brownish spots, paler and more yellowish towards the margin, margin bright citrus yellow, somewhat viscid. Lamellae crowded, very pale brownish grey when young, later brown. Stipe 4–6 cm long, 1.3–1.7 cm thick at the apex, up to 2.5 cm at the base, with a marginate bulb, white with a very faint, yellow tint. Context white. Universal veil not recorded. Mycelium white. Odour indistinct. Basidiospores 10.5–12×6–7 µm, amygdaloid-citriform to citriform, moderately to strongly, coarsely verrucose. Basidia hyaline, with hyaline oil drops. ITS sequence (GenBank ON843397, ex holotype) distinct from other members of Calonarius and with 98% similarity to the closest known species, C. calojanthinus (C. corrosus ss auct.).
Habitat and distribution – In coniferous forests on calcareous ground and and so far known from China and North America, Alaska, Arizona and Mexico.
Material examined – Mexico, Veracruz, Cofre de Perote, coniferous forest, 1965, H. L. Evans no. 4 (K(M)). USA, Alaska, Fairbanks, trails at the NW side of the campus, at the end of Yukon Road (trail starting from parking place), Picea dominated forest with some Betula, Populus and Alnus, on rich ground, 15 August 2011, K. Liimatainen, T. Niskanen 11-083, 001434093 (holotype in K-M; isotype in H).
GenBank numbers – HLE 4: ITS=ON843431; TN11-083: ITS=ON843397.
Notes – Typical characters for the species are the lack of purplish tints in the basidiomes, ochre brown pileus with a bright yellow margin, white stipe with a very faint yellow tint, and white context. The species belongs to the C. subgenus Calochroi. The North American-European sister species C. calojanthinus (C. corrosus ss auct.) has pale ochraceous to cream-coloured pileus.
Figure 1 – Basidiomes of the species of the genus Calonarius. a Calonarius caesiofulvus (K-M 001434088, holotype). b Calonarius nobilis (K-M 001434089, holotype). c Calonarius pacificus (K-M 001434090, holotype). d Calonarius pulcher (K-M 001434092, holotype). e Calonarius subcorrosus (K-M 001434093, holotype). Photographs: a Matthew E. Smith, b–e Kare Liimatainen
Figure 2 – Basidiomes of the species of the genus Calonarius. a Calonarius caesiofulvus (K-M 001434088, holotype). b Calonarius nobilis (K-M 001434089, holotype). c Calonarius pacificus (K-M 001434090, holotype). d Calonarius pulcher (K-M 001434092, holotype). e Calonarius subcorrosus (K-M 001434093, holotype). Drawings: Tuula Niskanen. Scale bars: 10 µm
Figure 3 – The best scoring RAxML tree of the genera Calonarius and Mystinarius based on the ITS region. Related sequences were retrieved from GenBank. Twenty-five specimens were included in the analysis of the ITS region which comprises 663 characters after alignment. The tree is rooted with Mystinarius. Estimated base frequencies were: A=0.246760, C=0.199165, G=0.201141, T=0.352933; substitution rates AC=0.954938, AG=3.189949, AT=1.426518, CG=0.990207, CT=5.977045, GT=1.000000, gamma distribution shape parameter α=0.312392. Maximum likelihood bootstrap values higher than 50% are given at the nodes. The holotype specimens retrieved from the GenBank are in bold and black. The new species are in bold and blue. The subgenus of the species is indicated after the collection/GenBank no. of each specimen