Entoloma tenue (Karstedt & Capelari) Blanco-Dios, Tarrelos

Karstedt, Fernanda, Bergemann, Sarah E., Gates, Genevieve, Ratkowsky, David, Cunha, Kelmer Martins & Capelari, Marina, 2024, Species of Entoloma (Entolomataceae) with cuboidal basidiospores from Brazil, Phytotaxa 654 (1), pp. 1-76 : 58-60

Entoloma tenue (Karstedt & Capelari) Blanco-Dios, Tarrelos 17: 38. 2015.

[≡ Inocephalus tenuis Karstedt & Capelari , Nova Hedwigia 96: 297. 2013.]

Figs. 28 , 38g –h

Diagnosis:— Entoloma tenue is characterized by a slender basidiome with a brown umbonate pileus, usually translucent-striate, a long stipe, and large, cuboidal basidiospores with elongated angles that in some views resemble a star.

Description:— Pileus 9–17 mm diam., conical, conical-campanulate or conical-convex, umbonate, brown, translucent-striate, hygrophanous, glabrous, surface slightly adpressed-fibrillose, margin dentate with age. Pileus context thin, white. Lamellae adnexed, adnexed-sinuate, faces smooth, ventricose (<2.4 mm at deepest part), pale brownish grey or greyish, close with three tiers of lamellulae, margin irregular. Stipe 64–88 × 1–2.8 mm, cylindrical or attenuated upwards, centrally attached, light brownish grey-white, or with a beige base and brownish apex, glabrous, slightly striate and twisted, with a few adpressed fibrils, hollow, with white basal tomentum. Stipe context whitish. Odor and taste not observed. Spore print not observed.

Basidiospores cuboidal with elongated angles, sometimes resembling a star with 4–7 projections, 4-angled in profile view, excluding the projections 10–13.7 × 10–13.7 µm [xm = 11.9 (± 0.9) × 12.5 (± 0.8) µm, Q = 1–1.22, Qm = 1.05 (± 0.06), n = 40/3], including the projections 12.5–16.2 × 12.5– 17.5 µm [xm = 14.2 (± 1) × 15 (± 1.3) µm, Q = 1–1.18(–1.36), Qm = 1.06 (± 0.08), n = 30/3] and diagonally 16.2–20 × 16.2–21.2 µm [xm = 17.8 (± 1.08) × 18.8 (± 1.11) µm, Q = 1–1.17, Qm = 1.06 (± 0.05), n = 30/2], thin-walled. Basidia clavate, broadly clavate, 41–64 × 16–21 µm (n = 60/3), hyaline, thin-walled, 4-sterigmate. Cheilocystidia abundant, along the entire lamellar margin, cylindrical, cylindro-clavate or clavate, 36–131 × 7.5–12.5 µm (n = 60/3), hyaline or with straw yellow intracellular pigment, walls thin or slightly thickened. Pleurocystidia and pseudocystidia absent. Lamellar trama composed of parallel, cylindrical or sometimes broadly cylindrical hyphae, 2.5–21 µm diam. (n = 60/3), hyaline, more often with straw yellow, light brownish or brown intracellular pigment, thin-walled, septa more than 200 µm apart; sub-hymenium branched. Pileitrama composed of radially arranged hyphae, 7.5–27 µm diam. (n = 60/3), cylindrical or broadly cylindrical, hyaline or with brown intracellular pigment, thin-walled, septa distant. Pileipellis a cutis of prostrate, cylindrical hyphae, 3.7–15 µm diam. (n = 58/3), hyaline or more often with brown intracellular pigment, sometimes with dispersed encrusted pigment, thin-walled; terminal hyphae cylindrical or cylindro-clavate. Stipitipellis a cutis, hyphae cylindrical, 3.7–8.7(–14) µm diam. (n = 40/2), hyaline or with straw yellow or brownish intracellular pigment, thin-walled, septa distant. Caulocystidia absent. Clamp connections present in all tissues. Refractive hyphae present in the lamellar trama, context, pileipellis and stipitipellis.

Habitat:—Solitary or gregarious, in soil with litter, in the Atlantic Forest biome.

Distribution:— Entoloma tenue is known only from collections made in the type location, São Paulo, Brazil.

Additional material examined:— BRAZIL. São Paulo: São Paulo, Fontes do Ipiranga State Park, in the middle of the forest, 7 April 2005, M. Capelari et al. s.n. (paratype, SP), trail parallel to Avenida do Cursino, 24 January 2008, F. Karstedt & L.A. Silva Ramos FK1039 (Holotype, SP), trail towards Avenida do Cursino (near the Botanical Garden), 3 March 2011, F. Karstedt & J.J.S. Oliveira FK1922 (SP) .

Comments:— Entoloma tenue is phylogenetically closely related to E.procerum found in New Zealand andAustralia, and to E. albogracile ( Fig. 3 ). They share mycenoid basidiomes with an umbonate cap and cuboidal basidiospores with elongated angles that resemble a star or even a butterfly with open wings. But they differ in that Entoloma tenue has a slender basidioma, a conical or campanulate-umbonate pileus with darker brown translucent striation, and bigger basidiospores, 10–13.7 × 10–13.7 µm excluding the projections, 12.5–16.2 × 12.5–17.5 µm including the projections and diagonally 16.2–20 × 16.2–21.2 µm. Entoloma albogracile clearly differs by having a white to yellowish pileus with a blunt papilla, basidiospores measuring 8 × 12.5 µm and the absence of clamp connections (Horak 1975). Entoloma procerum [G.Stevenson 599 - K(M)98640, the holotype] has smaller basidiospores, 7.5–10 × 7.5–10 µm excluding the projections and 10–12.5 × 10–11.2 µm including the projections [suggesting that Stevenson measured the basidiospores including the projections or diagonally, 10 × 13 µm (Stevenson 1962)], and cheilocystidia clavate to inflated-clavate (not cylindrical-clavate), clearly differing from Entoloma tenue . Additionally, we did not analyse the morphology of the three collections named as Entoloma procerum that were included in the phylogenetic analyses.

Figures

FIGURE 3. Phylogenetic reconstruction of the species of Entolomataceae with cuboid basidiospores and related species based on the combined genes (nLSU, mtSSU, rpb2 and tef1). Bootstrap values (> 70%) from the maximum likelihood analysis are indicated above the branches. The species studied here are shown in boldface. AU: Australia, AT: Austria, BZ: Belize, BR: Brazil, CN: China, GY: Guyana, IN: India, MY: Malaysia, NZ: New Zealand, PG: Papua New Guinea, PR: Puerto Rico, RE: La Reunion, UK: Russia, SC: Seychelles, US: United States, VN: Vietnam. Dashed vertical line: have similarity in the morphology but no molecular support.

FIGURE 28. Entoloma tenue: a–b. basidiospores: a. MC s.n.; b. FK1922; c. basidium (FK1922); d–e. cheilocystidia: d. FK1922; e. MC s.n.; f. pileipellis (FK1922). Scales: a–e: 10 µm, f: 20 µm.

FIGURE 38. Basidiomas: a–b. Entoloma cervinum: a. FK0940; b. FK1770; c–e. E. dragonosporum: c. FK2100; d. FK2019; e. FK2095; f. E. mocamboense (FK1899); g–h. E. tenue: g. FK1039; h. FK1922. Photos: a–f, h: F. Karstedt, g: C. Puccinelli. Scale: 1 cm.