Myxarium legonii (P. Roberts) P. Roberts

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 legonii (P. Roberts) P. Roberts , Nordic Journal of Botany 37 (e 02394): 15, 2019.

Fig. 9 A, B, D

≡ Stypella legonii P. Roberts , Mycotaxon 69: 228, 1998. Holotype. United Kingdom. England: Surrey, Runnymede, Cooper’s Hill , Ulmus sp. , 5.III.1988 Legon ( K (M) 49367 ) .

Description.

Basidiocarps effused, covering a few mm, semitranslucent, gelatinous, whitish or greyish, adnate; hymenophore hydnoid, spines regularly arranged, acute, single or fasciculate, 0.1–0.5 mm long, 5–7 per mm; subiculum first watery greyish, semitranslucent, then whitish, opaque, sometimes shining, 0.02–0.05 mm thick; margin gradually thinning-out. Hyphal structure monomitic, hyphae hyaline, clamped; subicular hyphae thin-walled, predominantly subparallel, 1–3 μm in diam., tramal hyphae subparallel, subhymenial hyphae ascending, very thin-walled, and quickly collapsing, (1.2 –) 1.6–2.6 (– 3.2) μm in diam. (n = 60 / 3). Acicular crystals abundant among hyphal tissues, often aggregated in large groups up to 20 μm in the widest dimension. Hyphidia abundant, simple to branched, 1–1.5 μm in diam. at the apical part, distributed among basidia. Basidia four-celled, longitudinally septate, broadly ellipsoid to subglobose, pedunculate, (6.7 –) 6.8–9.5 (– 9.8) × (5.3 –) 5.8–7.3 (– 7.4) μm (n = 32 / 3), scattered, stalk up to 12 × 2–2.5 μm, sterigmata up to 7 × 1.5–2 μm. Basidiospores cylindrical to broadly cylindrical, often slightly curved, (4.6 –) 4.9–7.6 (– 8.2) × (2.6 –) 2.7–4.0 (– 4.4) μm (n = 90 / 3), L = 5.50–6.28, W = 3.29–3.35, Q’ = (1.4 –) 1.5–2.3 (– 2.6), Q = 1.68–1.89.

Distribution and ecology.

Europe ( France, Spain, United Kingdom); strongly decomposed wood of angiosperms.

Remarks.

Originally described as a member of Stypella Möller ( Roberts 1998) , the species was recently moved to Myxarium ( Spirin et al. 2019 b) . The species was, however, accepted as a species complex because available ITS sequences showed clear differences between the European and North American specimens. In the present study, the latter are excluded from our concept of M. legonii and assigned to M. spiniferum , described below.

Here we reassess M. legonii based on newly collected specimens from the western part of Europe, as well as a specimen collected in the locus classicus. We found the latter (TAAM 132119) to be morphologically identical to three recent specimens from France and Spain, of which one was sequenced. These all have considerably larger basidiospores than indicated in the protologue (where they were presumably measured from a spore print) and possess abundant acicular crystals in all parts of the basidiocarps (Fig. 9 ). Phylogenetic analysis shows that the specimen Spirin 9511, treated as M. legonii in our earlier study ( Spirin et al. 2019 b), is not conspecific with the rest of the European collections. This specimen from the European part of Russia has smaller basidia and shorter basidiospores than other European specimens of M. legonii , and it lacks crystals. However, all these differences may be age-dependent, and we are therefore unwilling to introduce a new species for this specimen without additional sampling. Myxarium legonii was also reported from Malawi ( Spirin et al. 2019 b). The identity of this material should be clarified with more specimens from southern Africa.

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.