Protohydnum album (Lloyd) 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 album (Lloyd) Spirin comb. nov.

Figs 7 C , 11 A

≡ Exidiopsis alba Lloyd , Mycological Writings 4 (44): 9, 1913. Lectotype (selected here, MBT 10025858 ) . Fig. 1929 (plate 177) in Lloyd, Mycological Writings 6, 1921. Epitype (selected here, MBT 10025859 ) . USA. Ohio: Butler Co., Ross Hanover Rd. , Platanus sp. , 19. VII. 1977 Burdsall 9422 ( CFMR HHB-9422 ; duplicate – LE 23063 *, studied; other duplicates – ILLS 00157217 , MIN 840751 , NY 01930202 ) .

= Seismosarca alba (Lloyd) Lloyd , Mycological Writings 6: 1045, 1921.

= Exidia alba (Lloyd) Burt , Annals of the Missouri Botanical Garden 8: 366, 1921.

= Gloeotromera alba (Lloyd) Ervin , Mycologia 48 (5): 692, 1956.

Description.

Basidiocarps first orbicular or pulvinate, later cerebriform or foliaceous, gelatinous, opalescent, pure white to beige, later pale ochraceous to brownish, up to 3 cm in diam., 3–15 mm thick, in dry condition brown and tough, margin elevated, partly detaching; lobes rounded, entire, 1–1.5 mm thick. Hyphal structure monomitic, hyphae hyaline, clamped, thin- to slightly thick-walled; context hyphae mostly interwoven, frequently anastomosing, 2–7 μm in diam., occasionally swollen at septa (up to 9 μm in diam.), embedded in gelatinous matrix, subhymenial hyphae predominantly ascending, rather loosely arranged, 1–3 μm in diam. Gloeocystidia abundant, yellowish or brownish, gradually tapering to the apex, more rarely narrowly clavate, occasionally bifurcate, embedded, (69 –) 76–260 (– 265) × (4.1 –) 5.0–11.4 (– 13.2) μm (n = 42 / 4). Hyphidia abundant, richly branched, 0.5–2 μm in diam. at the apex, occasionally forming a continuous layer up to 20 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid, sessile or very rarely with a strongly reduced stalk-like base (up to 2.5 × 2.5 μm), embedded, (12 –) 13–17.5 (– 18) × (8.8 –) 9.1–13.5 (– 13.7) μm (n = 40 / 4), sterigmata gradually tapering, up to 15 × 2–3 μm. Basidiospores smooth, thin-walled, cylindrical to broadly cylindrical, often slightly curved, (7.3 –) 7.6–11.2 (– 12.2) × (3.8 –) 3.9–6.1 (– 6.2) μm (n = 120 / 4), L = 9.37–10.14, W = 4.63–5.54, Q’ = (1.5 –) 1.6–2.3 (– 2.4), Q = 1.72–2.04.

Distribution and ecology.

North America ( USA – the eastern states); wood of angiosperms.

Remarks.

The species was first described as Exidiopsis alba ( Lloyd 1913) and then moved to the genus Seismosarca Cooke by Lloyd (1921). Burt (1921) treated E. alba under Exidia . Martin (1951) studied the original material of Seismosarca hydrophora Cooke , the generic type of Seismosarca , and concluded that it was an Auricularia species. Consequently, Ervin (1956) placed E. alba , as well as Tremella pululahuana Pat. , in a newly established genus, Gloeotromera Ervin . Wells (1957) showed that T. pululahuana is the same species as Ductifera millei , the generic type of Ductifera , which was also described from Pululahua, Ecuador. He therefore moved T. pululahuana to Ductifera and stated that E. alba was conspecific with the former species. We studied both the authentic material of T. pululahuana from Ecuador and numerous collections of the species so named from the USA. In our opinion, they should be treated separately, and E. alba is to be retained as the correct name for the North American species.

Lloyd did not provide any reference to studied specimens of E. alba in the protologue, nor in a later treatment of this species ( Lloyd 1913, 1917). Stevenson and Cash (1936) reported 34 specimens in Lloyd’s herbarium labelled as Heterochaete alba , Seismosarca alba , or S. albida , but none named E. alba . Specimens identified as E. alba are also lacking in MyCoPortal ( Miller and Bates 2017). It is therefore uncertain which collections were at Lloyd’s disposal when he prepared the species description. In the original description, he mentioned that anatomical features of E. alba were depicted by E. M. Wakefield ( Lloyd 1913: 9). This drawing was published eight years later ( Lloyd 1921); we designate it here as a lectotype (iconotype) of E. alba . Additionally, we provide E. alba with an epitype – a recent sequenced collection distributed among several herbaria.

Sequences of D. pululahuana published by Weiß and Oberwinkler (2001) actually belong to P. album . Differences between these species are discussed under Protohydnum pululahuanum .

Figures

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 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.