Protohydnum microperum (Kalchbr. & Cooke) 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 microperum (Kalchbr. & Cooke) Spirin comb. nov.

Fig. 11 I

≡ Tremella micropera Kalchbr. & Cooke , Grevillea 9 (49): 18, 1880. Holotype. South Africa. Eastern Cape: Blue Crane Route, Somerset East , on branches, [no collecting date] MacOwan 1351 ( K (M) 56709 , studied).

Description.

Basidiocarps cushion-shaped, gregarious, erumpent, ca. 1 mm in diam., gelatinous, semitranslucent, amber-coloured, up to 0.5 mm thick, in dry condition reddish-brown. Hyphal structure monomitic, hyphae hyaline, clamped, thin- or moderately thick-walled, ascending, 1.5–2.5 μm in diam., context hyphae not differentiated. Gloeocystidia abundant, hyaline or brownish, gradually tapering to the apex, embedded or slightly projecting, 32–83 × 4.7–9.9 μm (n = 10 / 1). Hyphidia abundant, richly branched, 1–1.5 μm in diam. at the apex, forming a continuous layer up to 20 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid, sessile, embedded, 15–23.5 × 9.8–14.2 μm (n = 12 / 1), sterigmata gradually tapering, up to 20 × 2.5–3 μm. Basidiospores smooth, thin-walled, cylindrical, slightly or distinctly curved, (9.8 –) 10.3–15.3 (– 15.8) × (4.5 –) 4.6–6.5 (– 6.6) μm (n = 30 / 1), L = 13.31, W = 5.62, Q’ = (1.8 –) 1.9–2.8 (– 3.3), Q = 2.39.

Remarks.

Anatomically, P. microperum shows a certain similarity to P. aureum . These species can primarily be separated based on basidiocarp morphology (cushion-shaped and non-fusing in P. microperum versus pustulate and soon coalescing in P. aureum ) and the basidiospore width (spores in P. microperum are on average narrower than in P. aureum ). Protohydnum microperum is currently known only from the type locality in South Africa. Wells (1958) moved the species to Ductifera and treated Seismosarca tomentosa Olive , described from Georgia ( USA), as its later synonym. As we could judge from the protologue ( Olive 1947), S. tomentosa has a completely different basidiocarp configuration (effused, strongly darkening after drying, and possessing a white tomentose margin) and much larger basidiospores than P. microperum . It seems that the description of D. micropera by Wells (1957) refers mainly to S. tomentosa . After studying the type material of P. microperum , we found that they could hardly be conspecific; S. tomentosa certainly deserves a closer study.

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.