Elmericium alabastrinum Spirin & V. Malysheva, 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

Elmericium alabastrinum Spirin & V. Malysheva sp. nov.

Figs 7 A , 8 A

Holotype.

Russia. Khabarovsk Reg.: Khabarovsk Dist., Hologu , Populus maximowiczii (partly corticated fallen log), 17.VIII.2012 Spirin 5311 * ( H, isotype – in LE).

Etymology.

Alabastrinus (Lat., adj.) – alabaster-like; in reference to the hymenium colours.

Description.

Basidiocarps effused, up to 5 cm in widest dimension, smooth or indistinctly tuberculate, gelatinous, opalescent, greyish-white, often with reddish-brown spots, 0.5–1 mm thick, in dry condition opaque, pinkish-grey or grey, with vinaceous-brown or brownish-black stains, crustose, margin sharply delimited, usually slightly elevated, adnate or detaching, concolourous with hymenial surface. Hyphal structure monomitic, hyphae hyaline or brownish, clamped; subicular hyphae thick-walled, subparallel, 3–5 μm in diam., subhymenial hyphae thin- to slightly thick-walled, interwoven or ascending, densely arranged, 2–4 μm in diam., with occasional inflations up to 6 μm in diam. Cystidia abundant, hyaline, clavate to somewhat tapering, 20–30 × 5–8 μm, slightly projecting. Hyphidia abundant, richly branched, 1–2 μm in diam. at the apex, usually forming a continuous layer up to 15 μm thick. Basidia four-celled, longitudinally septate, ovoid-ellipsoid to obconical, pedunculate (petiolate), (16 –) 17–27.5 (– 30) × (9.8 –) 10.1–14.0 (– 14.3) μm (n = 30 / 2), stalk up to 26 × 5–6 μm, narrowing to the base, sterigmata tubular, gradually tapering, up to 23 × 3–4 μm. Basidiospores smooth, thin-walled, broadly ellipsoid to ellipsoid, (8.0 –) 8.6–12.2 (– 12.3) × (5.7 –) 5.9–8.1 (– 8.2) μm (n = 50 / 2), L = 10.23–10.32, W = 7.03–7.20, Q’ = (1.2 –) 1.3–1.7 (– 1.8), Q = 1.43–1.48.

Distribution and ecology.

East Asia (Russian Far East); corticated logs or still-attached branches of deciduous trees (mostly Populus ) along riversides.

Remarks.

At present, Elmericium alabastrinum is the single known corticioid representative of the Elmerina clade in the Auriculariaceae Fr. ex Lindau. All other members of this group ( Aporpium Bondartsev & Singer ex Singer , Elmerina , and Protodaedalea ) are poroid except Elmerina sclerodontia (Mont. & Berk.) Miettinen & Spirin , which has clavarioid basidiocarps (see Malysheva et al. 2018). Elmericium alabastrinum has petiolate basidia nearly identical in shape and size to those of Elmerina and Protodaedalea . However, the rest of the macroscopic traits (smooth, crust-like, gelatinous basidiocarps vs. poroid, cartilagineous, or leathery ones) and anatomical features (hyphal structure, hymenial construction, and basidiospore shape) clearly separate Elmericium from its relatives. The freshly collected basidiocarps of E. alabastrinum are usually sterile, although they start active sporulation after being rehydrated for several hours.

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 8. Basidiospores of: A. Elmericium alabastrinum (holotype); B. Hydrophana fessula (holotype); C. H. trichiesiana (holotype); D. Mycostilla chromatica (holotype); E. M. guianense (holotype); F. M. inconspicuum (holotype); G. Protoacia crispans (holotype); H. P. reliqua (holotype). Scale bar: 10 µm.