Protohydnum elevatum V. Malysheva & Spirin, 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

Protohydnum elevatum V. Malysheva & Spirin sp. nov.

Fig. 11 D

Holotype.

Russia. Sakhalin Reg.: Kunashir , Actinidia kolomikta (dry branch), 17.VIII.2017 Bulakh ( LE F-347688 *, isotype – H).

Etymology.

Elevatus (Lat., adj.) – elevated; referred to the basidiocarp margin.

Description.

Basidiocarps adpressed-orbicular to cerebriform, erumpent, up to 0.5 cm in diam., first solitary, then partly fusing together, gelatinous, semitranslucent, ivory-yellowish or pale ochraceous, up to 1 mm thick, in dry condition brownish and crustaceous, margin elevated, adnate; lobes poorly pronounced, rounded, entire, 0.5–1 mm thick. Hyphal structure monomitic, hyphae hyaline, clamped, thin-walled, easily collapsing; context hyphae interwoven, 2.5–5 μm in diam., embedded in gelatinous matrix, subhymenial hyphae ascending or interwoven, rather loosely arranged, 2–4 μm in diam. Gloeocystidia abundant, hyaline to yellowish, often distinctly tapering to the apex, embedded, (23 –) 26–46 (– 51) × (5.2 –) 5.3–7.8 (– 8.1) μm (n = 20 / 1). Hyphidia abundant, richly branched, 1–1.5 μm in diam. at the apex, forming a continuous, loose layer up to 15 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid, sessile, often distinctly tapering to the base, embedded, (18 –) 24–34 (– 40) × (11.8 –) 12.0–15.9 (– 16.7) μm (n = 20 / 1), sterigmata gradually tapering, up to 25 × 4–6 μm. Basidiospores smooth, thin-walled, ellipsoid-ovoid to broadly cylindrical, more rarely cylindrical and slightly curved, (11.0 –) 11.8–15.7 (– 16.2) × (7.4 –) 7.8–10.1 (– 11.1) μm (n = 30 / 1), L = 13.16, W = 8.91, Q’ = (1.2 –) 1.3–1.7 (– 1.8), Q = 1.49.

Distribution and ecology.

East Asia ( Russia – Kuril Ids.); dead angiosperm wood.

Remarks.

Protohydnum elevatum is a close relative of P. lactescens from North America (Figs 1 , 2 ). It differs from the latter species in having larger basidia and wider basidiospores, as well as shorter gloeocystidia. The species is currently known only from the type locality in East Asia.

Figures

Figure 1. Bayesian majority-rule consensus ITS + LSU-based tree of the Auriculariales overlaid with bootstrap support values from the maximum likelihood analysis. Support values are given as Bayesian posterior probabilities / ML bootstrap percentages. Species with stalked basidia are marked with a red X. I – Protohydnum clade; II – Elmerina clade; III – Hydrophana clade; IV – Endoperplexa – Mycostilla clade; V – Protoacia – Gelacantha clade; VI – Protomerulius clade; VII – Myxarium clade. The Sebacinales (Ditangium P. Karst., Sebacina, and Serendipita P. Roberts spp.) and Exidiopsis gloeophora were used as outgroups.

Figure 2. Bayesian majority-rule consensus ITS-based tree of the Protohydnum clade. Support values are given as Bayesian posterior probabilities. Basidiodendron spp. were used as an outgroup.

Figure 11. Basidiospores of: A. Protohydnum album (specimen Miettinen 196583); B. P. aureum (holotype); C. P. elasticum (holotype); D. P. elevatum (holotype); E. P. erumpens (holotype); F. P. galzinii (three left – specimen Miettinen 15900.4, three right – lectotype of S. galzinii); G. P. lactescens (four left – specimen TAAM 192048, three right – holotype of S. lactescens); H. P. livescens (specimen Spirin 13913); I. P. microperum (holotype); J. P. nudum (holotype); K. P. ocellatum (holotype); L. P. pallidum (holotype); M. P. pululahuanum (three left – lectotype, three right – specimen FH 00783538); N. P. sucinum (three left – lectotype of A. brasiliensis, three right – specimen BPI 701268); O. Protomerulius amiliavi (holotype); P. P. deceptorius (holotype). Scale bar: 10 µm.