Entoloma pleurotoides

Entoloma pleurotoides Xiao L. He & E. Horak

MycoBank number: 817514

Pileus 5–15 mm, conchate, broadly convex, becoming applanate with age, entirely matted-tomentose to matted-appressed fibrillose, membranous, whitish at first, becoming orange-white, yellowish-white and finally pale pinkish with age, slightly hygrophanous, margin not transparent-striate. Lamellae 7–11, with 1–2 tiers of lamellulae, adnexed, distant, narrow, up to 1.5 mm wide, subventricose, white at first, becoming pinkish with age, entire edges concolorous. Stipe 1–2.5 × 0.5–1 mm, strongly reduced, lateral, pale grey brownish, covered with minutely, pale greyish fibrils, base with white mycelium, white basal rhizoids present. Context thin, unchanging. Odour absent. Taste not distinctive. Basidiospores 8–10 × (7) 7.5–9.5 µm (x = 9.2 ± 0.2 × 8.4 ± 0.3 µm), Q = 1.0–1.25, Q = 1.1 ± 0.03, 5–6-angled, isodiametric to subisodiametric, 5–6-angled in profile view, with pronounced angles. Basidia 32–40 × 12–14 µm, clavate, 4-spored, clampless. Lamellar edge fertile. Cheilocystidia, pleurocystidia and caulocystidia absent. Pileipellis a cutis composed of cylindrical hyphae, terminal cells (25–) 30–40 × 3–8 µm, subclavate or cylindrical (rarely also subfusoid), repent or slightly uplifted, non-gelatinised wall thin, smooth, with inconspicuous plasmatic pigment, subpellis composed of short-celled cylindrical hyphae, 5–10 µm diam. Oleiferous hyphae present in pileipellis. Clamp-connections present.

Habitat: Amongst moss at base of living Castanopsis sp. or on decaying debris of Castanopsis sp.

Additional materials examined: China. Yunnan Prov.: Jingdong County, Ailao Mountain, ca. 2500 m elev., 24°23'N, 100°47'E, amongst moss at base of living Castanopsis sp., 10 September 2015, X.L. He (SAAS 1354); on decaying debris of Castanopsis sp., 10 September 2015, X.L. He (SAAS 1215; ZT 13613); Wuliang Mountain, ca. 2200 m elev., 24°45'N, 100°30'E, amongst moss at base of living Castanopsis sp., 9 September 2015, X.L. He (SAAS 1007).

Notes: Entoloma pleurotoides is characterised by white, small and pleurotoid basidiomes, presence of basal rhizoids and isodiametric to subisodiametric basidiospores. Macromorphologically, E. pleurotoides closely resembles E. pitereka which, however, differs by more heterodiametric basidiospores. Two other Australian species of Claudopus (C. rupestris, C. viscosus) possess basal rhizoids but, contrary to E. pleurotoides, are recognised by 4–5-angled, heterodiametric basidiospores. Basal rhizoids are also reported for the Indian E. indocarneum, which is separated by smooth pileus and more pronounced heterodiametric basidiospores (7.5–10 × 5–7 µm). Concerning macromorphologic characters, E. pleurotoides is difficult to separate from the following E. flabellatum discovered in China; however, the latter differs by the more distinctive heterodiametric basidiospores. In addition, molecular evidence further confirms that the two taxa represent two defined species. The ITS sequences of E. flabellatum are 88% identical to those of E. pleurotoides.

Fig. 1 Phylogenetic reconstruction of Claudopus based on ITS sequences. Maximum parsimony bootstrap values (BS > 50%) are indicated above or below the branches, new species are in bold.