Hydrophana trichiesiana Gruhn & Rödel, 2025

Spirin, Viacheslav, Malysheva, Vera, Viner, Ilya, Alvarenga, Renato Lúcio Mendes, Grebenc, Tine, Gruhn, Gérald, Savchenko, Anton, Grootmyers, Django, Ryvarden, Leif, Vlasák, Josef, Larsson, Karl-Henrik & Nilsson, R. Henrik, 2025, Additions to the taxonomy of the Auriculariales (Basidiomycota) with pedunculate basidia, MycoKeys 120, pp. 339-392 : 339-392

Hydrophana trichiesiana Gruhn & Rödel sp. nov.

Figs 6 A , 7 B , 8 C

Holotype.

French Guiana. Régina: Noruragues, Saut Pararé , rotten wood of angiosperm, 4.XII.2018 Gruhn GUY 18-573 * ( LIP, isotype – H).

Etymology.

Trichiesianus (Lat., adj.) – in homage to Gérard Trichies, a famous discoverer of minuscule heterobasidiomycetes.

Description.

Basidiocarps effused, up to 3 cm in widest dimension, tuberculate, gelatinous, opalescent, cream-coloured to pale ochraceous, 0.2–0.3 mm thick, in dry condition ochraceous-brown, vernicose, margin gradually thinning-out. Hyphal structure monomitic, hyphae hyaline, clamped; subicular hyphae thin-walled, interwoven or subparallel, 2–3 μm in diam., subhymenial hyphae very thin-walled, quickly collapsing, interwoven, rather densely arranged and partly glued together, 1–2 (– 2.5) μm in diam. Cystidia absent. Hyphidia abundant, richly branched, 0.8–1.2 μm in diam. at the apex, partly covering hymenial cells. Basidia four-celled, longitudinally septate, broadly ellipsoid to globose, sessile or pedunculate, (8.0 –) 8.2–9.8 (– 10.1) × (7.4 –) 7.8–8.8 (– 9.0) μm (n = 20 / 1), stalk usually strongly reduced, up to 3 × 2 μm, sterigmata gradually tapering, up to 18 × 1.5–2 μm. Basidiospores smooth, thin-walled, ellipsoid to broadly ellipsoid, the longest spores broadly cylindrical and sometimes slightly curved, (5.1 –) 5.2–7.0 (– 7.2) × (3.7 –) 3.8–4.7 (– 4.8) μm (n = 30 / 1), L = 6.08, W = 4.21, Q’ = (1.2 –) 1.3–1.7 (– 1.8), Q = 1.45, often with a large central oil drop.

Distribution and ecology.

South America ( French Guiana); decorticated, decayed angiosperm wood.

Remarks.

Hydrophana trichiesiana is described here as the first representative of the genus found in the tropics. It differs from the two other species of the genus, H. fessula and H. sphaerospora , in having basidia with a strongly reduced, although still detectable, stalk. Basidiospores of H. trichiesiana are similar to those of H. fessula , although slightly narrower on average.

Figures

Figure 6. Basidiocarps of: A. Hydrophana trichiesiana (holotype); B. Mycostilla chromatica (holotype); C. Myxarium guianense (holotype); D. Protoacia reliqua (holotype); E. Protohydnum erumpens (holotype); F. P. livescens (specimen Spirin 15619); G. Protomerulius amiliavi (holotype); H. P. deceptorius (specimen Spirin 16784). Scale bar: 1 cm.

Figure 7. Microscopic structures of: A. Elmericium alabastrinum (holotype) (1 – hymenial cells and subhymenial hyphae; 2 – subicular hyphae); B. Hydrophana trichiesiana (holotype); C. Protohydnum album (specimen Miettinen 196583); D. P. galzinii (specimen Miettinen 15900.4). Scale bar: 10 µm.

Figure 8. Basidiospores of: A. Elmericium alabastrinum (holotype); B. Hydrophana fessula (holotype); C. H. trichiesiana (holotype); D. Mycostilla chromatica (holotype); E. M. guianense (holotype); F. M. inconspicuum (holotype); G. Protoacia crispans (holotype); H. P. reliqua (holotype). Scale bar: 10 µm.