Protohydnum pallidum Spirin & Ryvarden, 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 pallidum Spirin & Ryvarden sp. nov.

Figs 10 C , 11 L

Holotype.

Zimbabwe. Manicaland: Rhodes Inyanga Nat. Park, Nyazengu , corticated hardwood branch, 16.I.1989 Ryvarden 26180 * ( O, isotypes – H, LE).

Etymology.

Pallidus (Lat., adj.) – pale, in reference to pale-coloured basidiocarps.

Description.

Basidiocarps effused, erumpent, up to 6 cm in widest dimension, smooth or indistinctly folded, cartilagineous, opaque, cream-coloured to pale ochraceous, 1–1.5 mm thick, in dry condition brown, vernicose, margin sharply delimited, sometimes slightly elevated, adnate or partly detaching. Hyphal structure monomitic, hyphae hyaline, clamped, homogeneous throughout, ascending or interwoven, embedded in gelatinous matrix, 2–3 μm in diam. Gloeocystidia abundant, yellowish-brownish, tapering or tubular-clavate, embedded, 85–165 × 9.5–17 μm. Hyphidia abundant, richly branched, 1.5–2 μm in diam. at the apex, forming a continuous layer up to 15 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid, pedunculate, (22 –) 23–31 (– 32) × (14.2 –) 14.4–19.8 (– 20.2) μm (n = 20 / 1), stalk up to 22 × 4–5.5 μm, sterigmata gradually tapering or apically swollen, up to 17 × 6–7 μm. Basidiospores smooth, thin-walled, ellipsoid to broadly ellipsoid, (14.0 –) 14.7–17.1 (– 17.2) × (10.1 –) 10.2–13.0 (– 13.1) μm (n = 30 / 1), L = 15.77, W = 11.58, Q’ = (1.1 –) 1.2–1.5 (– 1.7), Q = 1.37, cytoplasm with one or several large oil drops.

Distribution and ecology.

Africa ( Zimbabwe); still corticated angiosperm branches.

Remarks.

The species is introduced here based on extensive material collected in southern Africa. Morphologically, P. pallidum is reminiscent of the Australian Sebacina megaspora G. W. Martin , combined in Ductifera by Wells (1957). However, Ductifera megaspora (G. W. Martin) K. Wells has sessile, subglobose basidia and much larger basidiospores than those of P. pallidum (see descriptions in Martin 1936 and Wells 1957). The identity of D. megaspora remains obscure.

Figures

Figure 10. Microscopic structures of: A. Protohydnum lactescens (specimen TAAM 192048) (hymenial cells and tramal hyphae); B. P. livescens (specimen Spirin 13913) (hymenial cells and subhymenial hyphae); C. P. pallidum (holotype) (gloeocystidia and a basidium); D. P. sucinum (lectotype) (1 – basidia and basidiospores; 2 – gloeocystidia). Scale bar: 10 µm.

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.