Atheliella conifericola S.L. Liu & L.W. Zhou, sp. nov.

Index Fungorum number: IF 901057; Mycobank number: MB 901057; Facesoffungi number: FoF 14810; Figs. 1, 2

Etymology: conifericola (Lat.) referring to occurrence on conifers.

Holotype: LWZ 20191104–36 (HMAS).

Diagnosis: Characterized by the pellicular basidiomes with cracked and peeped out, brownish subiculum, loosely intertwined subicular hyphae, the absence of cystidia, and ellipsoid basidiospores.

Basidiomes resupinate, effused, thin, loosely adnate, soft, membranous, up to 10 cm long, 5 cm wide, 200 µm thick. Hymenophore smooth, continuous, whitish, pinkish buff when dry. Subiculum cracked, peeped out brownish. Margin thinning out, brownish.

Hyphal system monomitic; generative hyphae with clamp connections; subicular hyphae yellowish, thick-walled, moderately branched at right angles, 3 µm in diam; subhymenia hyphae hyaline, thin-walled, frequently branched. Cystidia absent. Basidia clavate, with four sterigmata and a basal clamp connection, 14–18 × 3.5–5 µm. Basidiospores ellipsoid, hyaline, thin-walled, smooth, IKI–, CB–, 3.8–4.2 × 2–2.3 µm, L = 4 µm, W = 2.2 µm, Q =1.8 (n=60/2).

Material examined: China, Yunnan Province, Dali Bai Autonomous Prefecture, Cangshanerhai National Nature Reserve, Cangshan Mountain, on stump of Pinus, 4 November 2019, L.W. Zhou, LWZ 20191104–36 (HMAS, holotype); ibid., on fallen trunk of Pinus, 4 November 2019, L.W. Zhou, LWZ 20191104–37 (HMAS).

GenBank numbers: LWZ 20191104–36: LSU = OR527280; LWZ 20191104–37: ITS= OR557254, LSU=OR527281.

Notes: Morphologically, Atheliella conifericola resembles Athelia bombacina by thin and pellicular basidiomes, loosely intertwined subicular hyphae with encrusted crystals, clamp-connected hyphae, the absence of cystidia, and ellipsoid basidiospores (Eriksson and Ryvarden 1973; Bernicchia and Gorjón 2010). However, Athelia bombacina differs in its whitish basidiomes and larger basidiospores (4.5–6×2.5–3 µm, Eriksson and Ryvarden 1973; 4.5–5.5×2.5–3 µm, Bernicchia and Gorjón 2010).

Figure 1 – Basidiomes of Atheliella conifericola (LWZ 20191104–36, holotype). Scale bars: a=1 cm, b=1 mm

Figure 2 – Microscopic structures of Atheliella conifericola (LWZ 20191104–36, holotype). a A vertical section of basidiomes. b Basidiospores. Scale bars: 10 μm

Figure 3 – Phylogeny generated by the maximum likelihood algorithm based on combined ITS and nLSU regions is presented along with the bootstrap values and the Bayesian posterior probabilities above 50% and 0.8, respectively, at the nodes. Coniophora marmorata MUCL 31667 and Pseudomerulius aureus FP-103859 were selected as the outgroup taxa. Holotypes are in bold and the newly generated sequences are in blue