Myxariellum concinnum V. Spirin & V. Malysheva, in Spirin et al., Nordic Journal of Botany 37: 8 (2019)
Etymology: Concinnus (Lat., adj.) – delicate.
Diagnosis: Basidiocarps semitranslucent, effused, continuous, smooth, gelatinous, greyish, adnate, 0.02–0.05 mm thick, margin indistinct; mineral inclusions absent. Hyphal structure monomitic; hyphae clamped, more or less uniform, thin-walled, 1–3 μm in diam. Cystidia scattered, thin-walled, tapering, 15–38 × 6–8.5 μm; hyphidia abundant, simple to sparsely branched, 1–1.5 μm in diam. at the apical part. Basidia 4-celled, (8.2–) 9.1–12.8 (–13.8) × (8.0–) 8.1–9.8 (–10.0) μm (n = 20/1), openly arranged; enucleate stalk up to 11 × 3 μm; sterigmata up to 6–10 × 2–3.5 μm. Basidiospores ellipsoid to broadly cylindrical, often slightly curved, longest spores somewhat fusiform, (6.9–) 7.2–9.7 (–10.2) × (4.0–) 4.1–5.0 (–5.2) μm (n = 30/1), L = 8.31, W = 4.47, Q = 1.87.
Distribution and ecology. North America (United States – Washington); rotten wood of Thuja. So far known from the type locality only.
Index Fungorum number: IF829010
Notes: Smooth, very thin basidiocarps, well-developed cystidia and rather big, occasionally subfusiform basidiospores differentiate Myxariellum from other species.
Figure 1. Combined phylogenetic nrITS+nrLSU topology from maximum likelihood analysis showing main lineages within Auriculariales. All sequences generated for this study are indicated in bold faces. Collection numbers of specimens are given for all sequences. Full red circle indicates clades that include taxa with sphaeropedunculate basidia (empty circle indicates absence of this feature). Support values (ML/BA) are given above the branches. Scale bar shows expected changes per site.