Xylodon attenuatus Spirin & Viner

Viner, Ilya, Spirin, Viacheslav, Zibarova, Lucie & Larsson, Karl-Henrik, 2018, Additions to the taxonomy of Lagarobasidium and Xylodon (Hymenochaetales, Basidiomycota), MycoKeys 41, pp. 65-90 : 69

Xylodon attenuatus Spirin & Viner sp. nov. Figure 3

Type.

USA. Washington: Jefferson Co., Hoh River, on Acer macrophyllum , 20 Oct 2014, V.Spirin 8775 (H) - ITS sequence, GenBank MH324476.

Etymology.

Attenuatus (lat., adj.) - exhausted, thin.

Description.

Basidiocarp effused, up to 5 cm in widest dimension. Sterile margin white, up to 1 mm wide. Hymenial surface cream-coloured, grandinioid to odontoid; projections rather regularly arranged, from 80 µm to 200 μm high, 70-90 μm broad at base, 6 –8(– 9) per mm. Hyphal structure monomitic, hyphae clamped, cyanophilous. Subicular hyphae densely interwoven, thin-walled, (2 –)2.4– 4.6 μm in diam. (n=60/6), often short-celled, the outline of these hyphae often irregular. Tramal hyphae subparallel, thin-walled, in subhymenium densely arranged, sometimes short-celled, 2.4-3.6 μm in diam. (n=62/6). Large stellate crystals 10-13.3 μm in diam. present in subiculum and trama. Cystidia originating from subhymenium, of two types: a) subcapitate or capitate cystidia, (12 –)13.5–25.1(–37)×(2.7–)3.3–5(– 5.5) μm (n=80/6), b) hyphoid cystidia, (14 –)16–38.3(–40.8)×2.8– 4.5 (n=51/6), sometimes with crystalline cap on the top; some cystidia with granular contents in CB. Basidia suburniform, 4-spored, (12.2 –)14–22(–25)×(3–)3.3–4.6(– 5) μm (n=61/2), slightly thick-walled at the base. Basidiospores thin-walled, ellipsoid, (3.7 –)4.1–5.5(–6)×(3–)3.4–4.5(– 4.9) μm (n=180/6), L=4.85, W=3.98, Q=1.22, slightly cyanophilous.

Distribution and ecology.

North-western USA (Washington), on angiosperm and gymnosperm wood (fallen decorticated logs).

Remarks.

Xylodon attenuatus bears morphological similarity to X. borealis , although densely arranged hyphae, star-like crystals and a regular presence of cystidia with granular contents make it easily recognisable. The crystalline caps on hyphoid cystidia are other characteristics useful for the identification of X. attenuatus .