Xylodon filicinus Yurchenko & Riebesehl

Riebesehl, Janett, Yurchenko, Eugene, Nakasone, Karen K. & Langer, Ewald, 2019, Phylogenetic and morphological studies in Xylodon (Hymenochaetales, Basidiomycota) with the addition of four new species, MycoKeys 47, pp. 97-137 : 97

Xylodon filicinus Yurchenko & Riebesehl sp. nov. Figs 3b, 5

Holotype.

TAIWAN, Nantou Co., Xitou (Shitou) Forest Recreation Area, W slope of Phoenix Mt. Range, 1470 m a.s.l., 23°40'N, 120°48'E, old-growth sparse broadleaf forest, on dead detached rachis of Cyathea sp., leg. E. Yurchenko, 31 Jul 2011 (field No. 38; MSK-F 12869; isotype in KAS).

Description.

Basidiomata effused, white, 2-4 cm in extent, farinaceous or pruinose, very loose or discontinuous, odontioid, 30-55 μm thick between aculei. Margin thinning out. Aculei conical or subcylindrical, 40-80 μm long, 15-45 μm diam., peg-like, of loose texture, 8-14/mm. Hyphal system monomitic, hyphae colourless, clamped at all septa. Subicular hyphae in a loose tissue, rarely branched, 2-3 μm diam., thin- or slightly thick-walled, loosely encrusted, under the subhymenium with inflations 5-6.5 μm wide. The largest crystals in subiculum 6-8 μm across, aggregated in clusters 15-18 μm diam. Subhymenial hyphae moderately branched, partly short-celled and slightly inflated, 2 –3.5(– 4) μm diam., lightly encrusted. Projecting hyphae in aculei richly encrusted, 20-45 × 5-7 μm in encrusted part, with clamped and simple septa, basally thick-walled, then becoming thin-walled, obtuse, sometimes subacute at apex. Cystidia in hymenium thin-walled, lightly encrusted, of three types: (1) subcylindrical, often slightly tapered to apex, numerous, 20-35 × 4.5-5.5 μm; (2) capitate, rare, 26-32 μm long, 3-5 μm wide at base, 2.5-3 μm wide at apex; (3) hyphoid to narrowly ventricose, about 30 × 4.5 μm. Basidioles ellipsoid, ovoid, clavate, 7.5-18 × 4.5-7.5 μm, more or less encrusted. Basidia utriform, (14 –)16– 20 × (3.5 –)4.5– 5.5 μm, thin-walled, smooth or sparsely encrusted, with four sterigmata 2-6.5 × 1-1.5 μm. Spores globose to subglobose, 4 –5(– 5.5) × (3.7 –)4– 4.5 μm, holotype L = 4.7 µm, W = 4.1 µm, Q = 1.1-1.2, thin-walled, often with one large oil-like globule, negative in Mz, weakly cyanophilous, with minute apiculus.

Distribution and ecology.

From the lower mountainous belt in Taiwan, on dead fern rachises.

Etymology.

from Latin filix ‒ fern, refers to the occurrence on dead fern rachises.

Additional specimen examined. TAIWAN, the same locality and the same substrate as holotype, leg. E. Yurchenko, 31 Jul 2011 (field No. 18; MSK-F 12870; dup. in KAS).

Remarks.

The distinctive features of this species are the pruinose, minutely odontioid basidiomata, fascicles of richly encrusted projecting hyphae in aculei and the three types of cystidia. Xylodon filicinus is morphologically similar to X. hyphodontinus , which differs in having projecting hyphae in the aculei that are straighter with more septa, a denser subhymenium composed of short-celled hyphae, short, ventricose cystidioles and spore walls that are slightly thickened at maturity (see Fig. 6).