Myxarium spiniferum 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

Myxarium spiniferum Spirin & V. Malysheva sp. nov.

Fig. 9 E

Holotype.

Canada. Alberta: Edmonton, Louise McKinney Riverfront Park , Populus alba (rotten decorticated log), 28.VII.2015 Spirin 8986 * ( H, isotype – LE).

Etymology.

Spiniferum (Lat., adj.) – bearing spines.

Description.

Basidiocarps effused, up to 3 cm in widest dimension, semitranslucent, gelatinous, whitish or greyish, adnate; hymenophore hydnoid, spines regularly arranged, acute, single or fasciculate, 0.1–0.6 mm long, 5–7 per mm; subiculum first watery greyish, semitranslucent, then whitish, opaque, 0.02–0.05 mm thick; margin gradually thinning-out. Hyphal structure monomitic, hyphae hyaline, clamped; subicular hyphae thin-walled, predominantly subparallel, 1–2 μm in diam., tramal hyphae subparallel, subhymenial hyphae ascending, very thin-walled, and quickly collapsing, (1.6 –) 1.9–3.0 (– 3.1) μm in diam. (n = 20 / 1). Acicular crystals quite rare, spread among hyphal tissues, often aggregated in large groups up to 20 μm in the widest dimension. Hyphidia occasionally present, simple to sparsely branched, 1–1.5 μm in diam. at the apical part, distributed among basidia. Basidia four-celled, longitudinally septate, broadly ellipsoid to subglobose, pedunculate, (6.0 –) 6.8–8.8 (– 9.2) × (5.3 –) 5.8–6.9 (– 7.0) μm (n = 20 / 1), partly glued together and often forming a continuous layer, stalk up to 8 × 2 μm, sterigmata up to 10 × 1.8–2.5 μm. Basidiospores cylindrical to broadly cylindrical, occasionally slightly curved, (4.1 –) 4.3–5.8 (– 5.9) × (2.3 –) 2.5–3.7 (– 3.8) μm (n = 90 / 3), L = 5.19–5.27, W = 2.98–3.13, Q’ = (1.4 –) 1.5–2.1 (– 2.2), Q = 1.70–1.75.

Distribution and ecology.

North America ( Canada – Alberta, USA – New York, Tennessee); strongly decomposed wood of angiosperms.

Remarks.

Myxarium spiniferum is described here as the North American sibling species of M. legonii . Morphologically, it differs from the latter species in having smaller basidiospores. The photograph of M. legonii in Spirin et al. (2019 b) belongs to M. spiniferum .

Figures

Figure 9. Microscopic structures of the Myxarium legonii complex: A. Myxarium legonii (specimen Spirin 16419) (hymenial cells and subhymenial hyphae); B. M. legonii (specimen Spirin 16419) (crystals); C. M. denticulatum (holotype) (basidiospores); D. M. legonii (specimen TAAM 132119) (basidiospores); E. M. spiniferum (holotype) (basidiospores). Scale bar: 10 µm.