Palliocystidium chlamydatum G. Gruhn & Ordynets 2025, gen. et sp. nov.

Palliocystidium chlamydatum G. Gruhn & Ordynets, gen. et sp. nov. Figs 2, 3, 4 Type FRANCE – French Guiana • Regina, integral reserve of Les Nouragues, Saut Pararé, path of the Nourague creek; 4°07’30”S, 52°72’60”W; on unknown deciduous tree (fallen corticated branch); 12 Jan. 2018; A. Ballester & G. Gruhn leg.; holotype: LIP [GG-GUY 18-115]. GenBank ITS = OQ 555356, LSU = OQ 555358. Diagnosis Differs from Palliocystidium oberwinkleri by the smaller basidiospores. Description Basidiocarps annual, resupinate, continuous, membranous, 8 × 2 cm, 20–40 µm thick, soft. Hymenial surface greyish, whitish when dry, smooth, porulose, velutinate under the binocular × 50. Margin adnate, indistinct, concolorous with hymenial surface. Smell indiscernible. Hyphal structure monomitic, tiny rounded clamps always present; subicular hyphae loosely interwoven, slightly brownish, with thickened walls, 3–5 µm in diam.; subhymenial hyphae thin- or only slightly thick-walled, rather loosely arranged and well visible, short cells (distances between neighbouring septa 8–12 µm), sometimes triangular when forked, 3.5–5 µm in diam. Cystidia numerous, hyphoid, thinning out with a rounded apex, single or bi-rooted, arising from hymenium layer, erected, 1–4 septate, basally thick-walled, thin-walled at the apex, at first smooth, then encrusted with oblong and irregular crystals of unknown matter, sometimes with septum and clamp, not reacting with Melzer’s, not cyanophilous, 54–64 (75) × 5 µm, 3 µm in diam. at the apex. Basidia clavate, with a median constriction, 15–18 × 6.5–7 μm, tetrasporic. Basidiospores hyaline, thin-walled, reniform, with flattened to slightly curved adaxial side, mostly uniguttulated, [47] (5.6) 6.0–7.3 (7.7) × (3.3) 3.7–4.3 (4.4) µm, Q 1.6–1.9, not amyloid, not dextrinoid, not cyanophilous. Distribution France (French Guiana), hitherto only known from two collections. Habitat and ecology Growing on dead, fallen branches of various deciduous trees in humid tropical forests of the neotropics. Etymology Chlamydatum (Latin, adj.) – dressed in chlamys, an ancient Greek cloak largely covering a human’s upper body and barely the lower body. Referring to the partial covering of the cystidium by the crystalline sheath. Additional material examined FRANCE – French Guiana • Regina, integral reserve of Les Nouragues, Saut Pararé, around the scientific station; A. Ballester & G. Gruhn leg.; paratype LIP [GG-GUY 18-371] dupl. KAS. GenBank ITS = OQ 555357. Notes The plate-like to irregular oblong crystals on cystidia and shorter basidiospores distinguish the species from Subulicystidium nikau (G. Cunn.) Jülich (Fig. 1 B). Several descriptions or iconography are available for the latter species (Cunningham 1963; Jülich 1968; Ordynets et al. 2018).