Entoloma pleurotoides Xiao L. He & E. Horak

He, Xiao-Lan, Horak, Egon, Wang, Di, Li, Tai-Hui, Peng, Wei-Hong & Gan, Bing-Cheng, 2019, Descriptions of five new species in Entoloma subgenus Claudopus from China, with molecular phylogeny of Entoloma s. l., MycoKeys 61, pp. 1-26 : 1

4. Entoloma pleurotoides Xiao L. He & E. Horak sp. nov. Figures 1g, h , 5

Type.

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 1252, holotype; ZT 13610, isotype).

Sequences ex holotype.

KU312113 (ITS), KU534227 (nLSU), KU534468 (RPB2), KU534424 (mtSSU).

Etymology.

pleurotoides (Lat.), referring to the pleurotoid shape of the basidiomes.

Diagnosis.

Entoloma pleurotoides is close to the Australian E. pitereka , but differs by smaller and more isodiameteric basidiospores.

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).

Remarks.

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 ( Noordeloos and Gates 2012). 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 ( Largent et al. 2011). Basal rhizoids are also reported for the Indian E. indocarneum ( Manimohan et al. 2006), which is separated by smooth pileus and more pronounced heterodiametric basidiospores (7.5-10 × 5-7 µm, Manimohan et al. 2002). 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 .

Figures

Figure 1. Basidiomes of Claudopus species a Basidiomes of E. conchatum on soil (SAAS 1712) b Basidiomes of E. conchatum on stem of live Pinus (SAAS 1014) c Pileus of E. flabellatum (SAAS 1501) d Lamellae of E. flabellatum (SAAS 1080) e Basidiomes of C. gregarious on bark-wood of live Castanopsis (SAAS 1220) f Red droplets on the lamellar edges of E. gregarium (SAAS 1493) g Basidiomes of E. pleurotoides on decaying bark-wood of Castanopsis (SAAS 1215) h Basidiomes of E. pleurotoides on bark-wood of live Castanopsis (SAAS 1252) i Basidiomes of E. reductum on decaying stump of Castanopsis (holotype, SAAS 1091) j Mature basidiomes of E. reductum on rock (SAAS 2068) k Young basidiomes of E. reductum on soil (SAAS 1016) l Lamellae of E. byssisedum var. microsporum (SAAS 1828) m Basidiomes of E. byssisedum var. microsporum on decaying stump of Betula (SAAS 1160).

Figure 5. Microscopic structures of Entoloma pleurotoides (holotype): a Basidia b Basidiospores c Pileipellis.