Protohydnum aureum (Lowy) 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 aureum (Lowy) Spirin comb. nov.

Fig. 11 B

≡ Ductifera aurea Lowy , Mycologia 68: 1106, 1976. Holotype. Panama. Chiriquí: Cerro Punta, Cerro Respingo , unidentified wood in oak forest, 2.VI.1975 Dumont & Carpenter PA- 1737 ( NY 00738326 , studied).

Description.

Basidiocarps first pustulate, gregarious, up to 1.5 mm in diam., then adpressed-cerebriform, up to 4 mm in diam., finally fusing together and forming compound crust-like fructifications up to 1 cm in the widest dimension, gelatinous, semitranslucent, amber-yellowish to pale ochraceous, 0.5–1 mm thick, in dry condition almost invisible, margin elevated, partly detaching; lobes poorly differentiated, rounded, entire, up to 0.5 mm thick. Hyphal structure monomitic, hyphae clamped; context hyphae thin- to slightly thick-walled, predominantly interwoven, hyaline or brownish, 1–4 μm in diam., embedded in gelatinous matrix, subhymenial hyphae thin-walled, ascending, hyaline, 1.5–3 μm in diam. Gloeocystidia abundant to rather rare, hyaline to yellowish, as a rule gradually tapering to the apex, embedded or rarely slightly projecting, 44–85 × 4.3–8.9 μm (n = 10 / 1). Hyphidia abundant, simple or sparsely branched, 0.5–1 μm in diam. at the apex, forming a continuous layer up to 10 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid, sessile, embedded, 18–24 × 9.7–13.5 μm (n = 10 / 1), sterigmata gradually tapering, up to 15 × 2–3 μm. Basidiospores smooth, thin-walled, cylindrical to broadly cylindrical, occasionally slightly curved, (10.0 –) 10.2–14.6 (– 15.4) × 5.5–7.2 (– 7.4) μm (n = 20 / 1), L = 12.84, W = 6.46, Q’ = (1.6 –) 1.7–2.5 (– 2.7), Q = 2.00.

Remarks.

Ductifera aurea was described from a single specimen collected in Panama ( Lowy 1976) and is so far not known elsewhere. Morphologically, it is most similar to P. album and P. pululahuanum . It differs from both of these in having considerably larger basidia and basidiospores. We transfer it to Protohydnum based on morphological evidence; our attempts to sequence the holotype were unsuccessful.

Figures

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.