Thaxterogaster obscurovibratilis – Facesoffungi number: FoF 14870

Thaxterogaster obscurovibratilis Niskanen, Liimat. & Ammirati, sp. nov.

Index Fungorum number: IF 900313; Mycobank number: MB 900313; Facesoffungi number: FoF 14870; Figs. 1d, 2d, 3

Etymology – The species belongs to Thaxterogaster sect. Vibratiles and has a darker pileus than other species of the section.

Holotype – K-M 001434124.

Pileus 2.5–5 cm in diam, at first hemispherical, later low convex to almost plain, sometimes with an umbo, dark reddish brown to pale yellowish brown, viscid to glutinous. Lamellae crowded, very pale greyish brown. Stipe 4–6 cm long, 0.4–0.8 cm thick at the apex, up tp 1.5 cm at the base, clavate to rarely almost bulbous with a tapered base, almost dry, whitish silky fibrillose. Context dark brown to brown in the pileus, white at the apex of the stipe, pale yellow towards the base. Universal veil white, sparse. Mycelium white. Taste very bitter on the pileus. Odour in lamellae and context more or less raphanoid. Basidiospores 6.5–7.5×4.5–5 µm, ellipsoid to amygdaloid-ellipsoid, almost smooth to very finely verrucose. Basidia hyaline, with hyaline oil drops. Lamellar trama hyphae hyaline with oil drops in 5% KOH. ITS sequence (GenBank ON843428, ex holotype) distinct from other members of Thaxterogaster and with 93% similarity to the closest known species T. vibratilis.

Habitat and distribution – In mixed forests and so far known from USA: California and Washington.

Material examined – USA, California, Humboldt Co., Big Lagoon, trail starting from the school, spruce forest with moss cover, 3 December 2012, J. Olsson & K. Liimatainen, T. Niskanen 12–225, 001434127 (K-M); Mendocino Co., Jackson State Forest, S of the crossing of roads 408 and 409 by road 720, mixed forest (Lithocarpus and Pseudotsuga), 26 November 2012, K. Liimatainen, T. Niskanen 12–151, 001434126 (K-M). Close to 408 road, Pseudotsuga and Lithocarpus, 8 December 2012, K. Liimatainen, T. Niskanen 12–276, 001434125 (K-M). loc. cit., K. Liimatainen, T. Niskanen 12–281, 001434124 (holotype in K-M; isotype in H). Washington, Gray’s Habor County, Ocean Shores, caespitose to gregarious under Tsuga heterophylla, 17 December 1979, M. McCaw, J. F. Ammirati 8464 (WTU).

GenBank numbers – TN12-151: ITS=ON843430; TN12-276: ITS = ON843429; TN12-281: ITS = ON843428; JFA8464: ITS=ON843433.

Notes – A unique looking species in the Thaxterogaster sect. Vibratiles due to the dark colour of the pileus and thus easy to distinguish from the other members of the section. Otherwise, the species has the typical characters of the section: basidiomes are rather small, pileus is viscid to glutinous, stipe is white and somewhat viscid to almost dry, and the spores are small, amygdaloid-ellipsoid and finely verrucose.