Amaurodermellus Costa-Rezende, Drechsler-Santos & Góes- Neto, gen. nov.
Index Fungorum number: MB833561; Facesoffungi number: FoF
Etymology: Amaurodermellus (Latin), in reference to the morphological similarity with Amauroderma.
Diagnosis: Characterized by a dark dull pilear surface, pale context, pileipellis as a short trichoderm, and ovoid, hyaline to pale yellow basidiospores, these with inconspicuous endosporic projections that are solid when observed under SEM.
Description: Basidiomata annual, stipitate, pleuropodal to pseudomesopodal; pileus semicircular, reniform to spathulate. Pilear surface glabrous, dark brown to black, slightly concen- trically zonate to azonate, radially rugose; context fibrous to coriaceus, whitish to cream, homogenous, with or without dark bands coming from stipe, in section with a dark cuticle. Tubes slightly darker than context. Pore surface cream to grayish. Pores regular, circular to angular; dissepiments thick, entire. Stipe cylindrical, brown, finely tomentose, solid to hol-low, context homogeneous, whitish to cream, with or without dark bands (mainly near the base), with a dark cuticle in sec- tion. Pileipellis a short trichoderm. Hyphal system di-trimitic, generative hyphae clamped, arboriform and skeleto-binding hyphae, pale yellowish, IKI-. Cystidia and cystidioles absent. Basidia clavate, 4-sterigmate. Basidiospores ovoid, non-trun- cate, hyaline to pale yellow, double-walled with inconspicu- ous endosporic ornamentation as solid column-like projec- tions, IKI-.
Habitat and distribution: Emerging from soil, probably as- sociated with buried roots, and is restricted to the Neotropical region in Cerrado (Mato Grosso, this work) and Amazon (Pará and Rondonia) biomes in Brazil (Gomes-Silva et al. 2015).
Typification: Amauroderma ovisporum Gomes-Silva, Ryvarden & Gibertoni, Phytotaxa 227:215. 2015.
Notes: – The combination of clamped generative hyphae, presence of arboriform and skeleto-binding hyphae, and double-walled basidiospores with an ornamented endospore places the genus in Ganodermataceae. The combination of stipitate basidiomata with a di-trimitic hyphal system and non-truncated basidiospores is similar to those observed in species of Amauroderma s.str., Foraminispora, and Magoderna. However, while Amaurodermellus presents ovoid basidiospores, Foraminispora has globose to subglobose basidiospores with hollow columns as endosporic ornamentations when viewed under SEM (Costa-Rezende et al. 2017) and Amauroderma s.str. has subglobose to ellipsoid basidiospores. The type species of Magoderna [M. subresinosum (Murrill) Steyaert] has a pale context and subovoid to ellipsoid basidiospores, but is char- acterized by having a black and very shiny pilear surface, which differs from the dull pileus of Amaurodermellus. In addition, M. subresinosum has a paleotropical distribution (Steyaert 1972). Phylogenetically, Amaurodermellus group ed in an inde pen d ent l inea ge among Ganodermataceae.