Scytinopogon minisporus J. Alvarez-Manjarrez, M. Villegas & R. Garibay-Orijel, sp. nov.

Index Fungorum number: IF 829209; MycoBank number: MB 829209; Facesofungi number: FoF 05672; Fig. 1

Etymology – Refers to the small-sized basidiospores.

Holotype – MEXU 28300.

Basidiocarps clavarioid 15–40 mm tall, branches are 15–17 mm long, stipe 5–15×1–3 mm long, acute to subounded, fat, and whitish or even grey (5A2–5B3), axils rounded. Branching near to the stipe is polytomical and near to the tips can be dichotomical to polytomical. Stipe cylindrical slightly fattened, whitish to pale orange-brown (5A2–5A3), base covered by numerous short hyphae looking plushy. Surface of all the fruitbody, except the base of the stipe, looks smooth to the naked eye, and dusty under the stereoscopic microscope. Consistency is cartilaginous to leathery. Flesh of middle portion has the same color as the surface. Odor indistinguishable, taste slightly astringent. Basidiospores 4.2–5(–5.6)×2.1–2.8(–3) µm [x=4.6±0.4×2.4±0.3 µm, Q=1.3–1.6, n=30], dacryoid, slightly elliptical in lateral view, hyaline, thin-walled, verrucose, sometimes the warts merge, without conical spines; plage non ornamented, with lateral hilar appendix, slightly cyanophylic. Basidia mostly tetrasporic, scarce, (10–)20.3–28×4.9–5.6 µm, cylindrical to subcylindrical, hyaline, thick -and smooth-walled, base with clamp connection. Sterigmata 2.8–4.2×1.4 µm, hyaline, straight with acute apex. Cystidia clavate, incrusted on the tip, non dissolving in KOH, very scarce. Subhymenium monomitic; generative hyphae of 1.4–3.5×50–56 µm, with thickened wall (<1 µm), septae with clamp connections, and H connections between hyphae. Tramal hyphae strictly parallel, (2.1–)2.8–3.5 µm, thickened wall (<1 µm), septate with clamp connections, and hyphae with H connections. Stipe composed of generative hyphae, 1.4–2.1 µm diam, hyaline, wall slightly thickened, frequent septa with clamp connections, and abundant crystals on their surface forming irregular plates.

Habitat and known distribution – Gregarious or solitary, growing on soil or debris of tropical dry forest from the Pacific coast of Jalisco, Mexico.

Material examined – MEXICO, Jalisco, municipality La Huerta, Estación de Biología de Chamela (EBCH), pathway Camino Antiguo, 9 October 2005, Villegas Ríos M. 2630 (FCME 26014); pathway Chachalaca, 11 August 2006, Villegas Ríos M. 2679 (FCME 26015); pathway Camino Antiguo Sur, 11 August 2006, Aguirre, Bautista and Pulido II-40 (MEXU 26345); 1 October 1977, A. Pérez J. and A. Solís M. (MEXU 11923); pathway Buho, 10 October 2015, Alvarez-Manjarrez AM170 (MEXU 28300, holotype); pathway Buho, 18 October 2015, Alvarez-Manjarrez AM176 (MEXU 28301, isotype).

GenBank numbers – ITS: MK328885, MK328886; LSU: MK328894, MK328895.

Notes – Phylogenetic analyses of the combined ITS and LSU dataset reveal Scytinopogon minisporus as sister to a clade comprising two undescribed Scytinopogon species from Australia and Taiwan island and S. af. pallescens from Mexico (Fig. 2). S. minisporus differs from other species of Scytinopogon in having clavate cystidia with crystals on the tip. Microscopically it is very similar to S. scaber (Berk. & M.A. Curtis) D.A. Reid, however S. minisporus has verrucose spores, bigger basidia and encrusted cystidia. S. papillosus Corner also is similar in spore size but has minute papillae on the surface of the fruitbody. It is important to note that Trechispora and Scytinopogon are paraphyletic in the same clade (Birkebak et al. 2013; Desjardin and Perry 2015). The type sequences of both genera are necessary to determine if the resupinate Trechispora and coralloid Scytinopogon are synonyms (Desjardin and Perry 2015). S. minisporus is allocated to this genus, based on the current concept while waiting for phylogenetic studies including sequences of type species.

Figure 1 – Scytinopogon minisporus. a Fresh fruitbody (FCME 26015). b Dry fruitbody (MEXU 28300, holotype). c Basidiospores with verrucose ornamentation, showing the plage without ornamentation (MEXU 28300, holotype). d Ornamentation of spores (MEXU 28301). e Immature basidiospores attached to a tetrasterigmata basidia. f Clavate cystidia with crystals on the tip. Scale bars: b=5 mm, c–e=1.5 µm, f=4 µm

Figure 2 – Bayesian analysis combined dataset of ITS and LSU sequence data of the Trechispora-Scytinopogon clade. The tree is rooted with Brevicellicium atlanticum and B. olivascens. The node support is indicated as maximum likelihood bootstrap and Bayesian posterior probabilities respectively. New sequences are indicated in blue