Xylodon follis Riebesehl, Yurchenko & Langer

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 follis Riebesehl, Yurchenko & Langer sp. nov. Figs 3c, 7

Holotype.

REUNION, Forêt Notre Dame de la Paix, Sentier botanique, 21°15.8'S, 55°36.1'E, 1720 m a.s.l., on angiosperm wood, leg. J. Riebesehl, M. Schröder, M.M. Striegel, 12 Mar 2015 (FR-0249814; isotypes in KAS (as L1040) and MSK).

Description.

Basidiomata effused, cream-coloured, about 1-5 cm in extent, soft-membranaceous, continuous, finely aculeate, between aculei 50-200 μm thick; aculei narrowly conical or nearly cylindrical, 80-170 × 20 –40(– 60) μm, 10-12/mm, fragile, slightly fimbriate at apices, sterile. Margin abrupt. Hyphal system monomitic; hyphae clamped and simple septate, colourless, (1 –)2– 3.5 μm diam. Subiculum little differentiated, composed of thin- to slightly thick-walled hyphae. Hyphae in aculeal trama mostly parallel, thin- to thick-walled (walls up to 1 μm thick), projecting through aculeal apices and loosely encrusted with crystals about 1-3 μm long in KOH. Subhymenium thickening; subhymenial hyphae moderately branched, thin-walled, smooth. Capitate cystidia numerous, projecting and immersed, in subhymenium, hymenium and aculei, 17 –30(– 40) × 4.5-9 μm, with 1-2 adventitious septa in stalk, apical cap encased with resinous encrustation 6-12 μm wide, easily dissolving in KOH and Mz, unchanged in CBL. Hyphidial elements common in hymenium, 17-27 × 2.3-3.2 μm. Basidioles pyriform or ellipsoid, 17-28 × 8-12 μm, with granular contents, smooth or slightly encrusted. Basidia utriform or suburniform, thin-walled, smooth, 32-37 × 9-10 μm, with 4 sterigmata 4-6.5 × 1.3-2.3 μm. Spores globose to subglobose, colourless, with homogeneous or granular contents, smooth, inamyloid, indextrinoid, cyanophilous, thin-walled, (7.5 –)8–9.5(– 10) × 7-8.5 μm, holotype L = 8.6 μm, W = 7.6 μm, Q = 1.0-1.2, outer wall layer sometimes swelling in KOH and CBL, with rounded-triangular apiculus.

Distribution and ecology.

The species is so far known from Réunion (Mascarene Archipelago) and inhabits dead wood.

Etymology.

from Latin follis ‒ bag or bubble, referring to shape of the spores, basidioles and capitate cystidia found in this species.

Additional specimen examined. REUNION, Forêt de Bébour, 1328 m asl., leg. E. Langer, G. Langer, E. Hennen, 20 Mar 1998 (KAS-GEL 4951; dupl. in MSK).

Remarks.

This taxon differs from other Xylodon species by its unusually large basidia, large globose basidiospores with walls that swell in KOH and CBL and numerous simple septa as well as clamps on the hyphae. The swelling of spore walls was observed in some spores; spores were unaffected in water mounts. The hymenium has a granular appearance visible under 100 × magnification because of the resinous cap developed on the capitate cystidia. The resinous caps are observed only in CBL and are easily detaching in squash preparations. Intermediate forms in morphology of hyphidia to capitate cystidia and of capitate cystidia to pyriform basidioles were frequently observed.