Cabalodontia tenuissima Westphalen & Regio 2026, comb. nov.

Cabalodontia tenuissima (C. L. Zhao & Y. X. Wu) Westphalen & Regio comb. nov. Basionym. Steccherinum tenuissimum C. L. Zhao & Y. X. Wu, PLoS ONE 16 (1): e 0244520, 7. 2021. Notes. Cabalodontia tenuissima was originally described based on a phylogeny that included only Steccherinum spp., where it nested in a separate clade with S. xanthum, a species shown by our analyses to be a synonym of C. albofibrillosa. Morphologically, C. tenuissima differs from all other confirmed Cabalodontia spp. by presenting a dimitic hyphal system, although it shares other features of the genus, such as fragile and thin basidiomes with an odontioid hymenophore (Wu et al. 2021 a). It is possible that the skeletal hyphae reported by the authors represent undifferentiated lower portions of skeletocystidia, since the incrustations are restricted to the apical region. This interpretation is also supported by the drawings presented in the original description, where clamped hyphae are abundant and few thick-walled skeletal hyphae are shown, which is not common in truly dimitic species. Such thick-walled hyphal segments are also observed in other species of the genus, such as C. brunnea and C. albofulva, but they are scarce and, when carefully observed, give rise to cystidia. Further examination of the specimens is required to confirm this hypothesis. Nevertheless, because our phylogenetic analyses are well supported and include sequences from the type material (CLZhao 3153), we chose to transfer this species to Cabalodontia. Together with Irpex oreophilus (Lindsay & Gilb.) Niemelä, these are the only two dimitic taxa recovered within the genus.