Favolus gracilisporus H. Lee, N.K. Kim & Y.W. Lim

Index Fungorum number: IF552508 Facesoffungi number: FoF 2626

Etymology: referring to a slenderer spore relative to other Favolus species.

Holotype: SFC20130704–40

Basidiocarps annual, lateral stipitate; pileus circular to flabellate, up to 40 mm in diam., up to 3.5 mm thick; pileal surface ivory to pale buff, with age becoming brown, fibrillose with flattened, radially striate, azonate, slightly glabrous, margin concolorous, acute, lacerate. Hymonophore cream to pale brown when fresh, pores diamond-shaped, radially elongated, 2–3 mm long, 1–2 mm wide near stipe to 2–3 per mm at margin; dissepiments thin and lacerate with age. Context in pileus pale tan to ivory, corky, brittle when dry, up to 0.5 mm thick. Tube continuous with the context, up to 2–3 mm thick. Stipe lateral, buff, glabrous, up to 7 mm long and 6 mm thick. Hyphal system dimitic; generative hyphae hyaline in KOH, thin-walled, 3–4 μm in diam., septa with clamps, skeletal-binding hyphae thick-walled, aseptate, much branched, with tapering apices, 3–6 μm diam. Cystidia absent. Basidia clavate, 4–sterigmate (up to 4.5 μm), 27–35 × 5.7–8 μm, with a basal clamp. Basidiospores cylindric, hyaline, smooth, IKI-, 7.9–9.7 × 2.5–3.3 μm. L = 9 μm, W = 2.9 μm, Q = 3.11 (n = 20/1).

Habitat: solitary to gregarious on dead wood of hardwood.

Material examined: KOREA, Gyeongsangbuk-do, Yecheon-gun, Mt. Hagga, on rotten angiosperm stump, 4 July 2013, Y.W. Lim (SFC20130704–40, holotype). GenBank number ITS:KY038472.

Notes: Favolus gracilisporus shares similar characteristics with Favolus brasiliensis (Fr.) Fr., Favolusroseus Lloyd, and Neofavolusalveolaris (DC.) Sotome & T. Hatt. such as lateral stipitate basidiocarps with radially elongated and hexagonal pores; however, F. gracilisporus has distinctly larger basidia (27–35 × 5.7–8 μm) compared to F. roseus (18–23.8 × 4.5–7 μm, Sotome et al. 2013) and N. alveolaris (17.5–26 × 4–7 μm, Sotome et al. 2013). Microscopic features of F. brasiliensis are somewhat similar to F. gracilisporus, but the latter species has a larger basidiospore Q value (3.11) than F. brasiliensis (Q = 2.75, Sotome et al. 2013). Phylogenetic analysis based on the ITS region indicated that F. gracilisporus separated distinctly from the other three species.

Phylogram generated from maximum likelihood (RAxML) analysis based on ITS sequence data of Favolus. Maximum likelihood bootstrap support values greater than 70% are indicated above or below the nodes and the new species is in bold. The tree is rooted with Neofavolus mikawai and N. alveolaris.


Favolus gracilisporus (SFC20130704–40, holotype). a, b Fruiting bodies in the field (SFC20130704–40). c Pores of fruiting body (SFC20130704–40). d Microscopic structure; basidiospores, basidia, generative hyphae and skeletal-binding hyphae.