Amphistereum Spirin & Malysheva, in Fungal Biology 121 (8): 696 (2017)
Etymology: ‘amphi-’ (Greek, prefix) e both ways, and Stereum, a genus of basidiomycetes; the name implies a high macroscopic similarity to other stereoid fungi
Diagnosis: Basidiocarps annual or perennial, cupulate-orbicular, hard leathery. Hymenophore smooth, pale coloured. Hyphal structure dimitic; skeletal hyphae coloured (pale to dark brown), non-branching and located in the uppermost part of context or richly dichotomously branching and then dominating in the whole basidiocarps; generative hyphae clamped. Cystidia rare, thin-walled. Basidia ellipsoid-ovoid, longitudinally septate, four-celled, embedded; no enucleate stalk. Basidiospores hyaline, cylindrical to thick cylindrical, slightly curved, with accidental oily inclusions. On dry, still attached or fallen branches of deciduous trees.
Index Fungorum number: IF818018
Type species: Amphistereum schrenkii (Burt) Spirin & Malysheva, in Fungal Biology 121 (8): 696 (2017)
Notes: The genus embraces two species with sturdy, dimitic basidiocarps. Richly branched skeletal hyphae are dominating in all parts of the A. leveilleanum basidiocarps. In A. schrenkii vegetative hyphae occur exclusively in the uppermost parts of the context, and they look like normal skeletal hyphae. Pronounced dimitic structure and smooth hymenium surface differ Amphistereum from Eichleriella (the sole dimitic representative of the latter genus, E. tenuicula, has spiny hymenophore) while ellipsoid-ovoid basidia make it distinguishable from Heteroradulum.
Amphistereum leveilleanum (Berk. & M.A. Curtis) Spirin & Malysheva 2017
Amphistereum schrenkii (Burt) Spirin & Malysheva 2017
Figure 1. Combined phylogenetic nrITS D nrLSU topology from Maximum likelihood analysis showing main lineages within Auriculariales. The collection number (voucher or isolate) is given for each specimen. Support values (PP values in BI/BS values in ML/BS values in MP) are given above the branches. Scale bar shows expected changes per site.