Entoloma amazonicum Karstedt & Capelari

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 : 20-22

Entoloma amazonicum Karstedt & Capelari , sp. nov.

Figs. 5 , 10d–f , 34a–b

MB 838583

Etymology:— Amazonicum refers to the species being collected in the Amazon Forest.

Diagnosis:— Entoloma amazonicum is characterised by the combination of a basidiome with a brown pileus tending to ochraceous, white lamellae, whitish fibrous stipe, and the presence of pseudocystidia as well as the cuboidal basidiospores.

Type:— BRAZIL. Pará: Caxiuanã, Caxiuanã National Forest , EsecaFlor plot, 10 February 2011, F. Karstedt et al. FK1815 (Holotype SP) .

Description:— Pileus 8–35 mm diam., conical, conico-campanulate, broadly conical or applanate with conical center, ochre, brownish ochre with center slightly paler than margin, glabrous, sometimes slightly waxy, translucent-striate, hygrophanous, surface slightly adpressed-fibrillose, margin in youth involute, becoming straight, smooth or slightly crenulate. Pileus context thin, <1 mm, white. Lamellae adnexed, adnexed-sinuate or sinuate, smooth, ventricose (<5 mm), white, beige or pinkish white, subdistant to close with two tiers of lamellulae, margin concolorous with faces and slightly irregular. Stipe 25–55 × 2–4 mm, cylindrical or slightly attenuated upwards, centrally attached, white or sordid white (off-white), beige or slightly grey-brown, sometimes more brownish at the base, glabrous, fibrillose, slightly striate and twisted, hollow, with white basal tomentum. Stipe context concolorous. Odor and taste not observed. Spore print not observed.

Basidiospores cuboidal with angles rarely slightly elongated, 4-angled in profile view, excluding the projections 7.5–10 × 8.75–11.2 µm [xm = 8.7 (± 0.56) × 9.3 (± 0.68) µm, Q = 1–1.16 (–1.33), Qm = 1.07 (± 0.09), n = 48/3], diagonally 10–12 × 10–12.5 µm [x m = 10.9 (± 0.62) × 11.2 (± 0.56) µm, Q = 1–1.12, Qm = 1.03 (± 0.06), n = 30/2], thin-walled. Basidia broadly cylindrical or broadly clavate, 39–55 × 11.2–15 µm (n = 29/3), hyaline, thin-walled, 4-sterigmate. Cheilocystidia abundant, along the entire lamellar margin, cylindrical, cylindrico-clavate, narrowly clavate, clavate, broadly clavate, fusoid or ventricose, sometimes branched, 31–100 × 8.7–16.2 µm (n = 30/3), hyaline, thin-walled. Pleurocystidia absent. Pseudocystidia hyphoid, 2.5–5 µm diam. (n = 12/1), strongly pigmented, honey-colored or brownish (in NH 4 OH), rarely straw yellow, thin-walled. Lamellar trama formed by parallel, cylindrical or cylindrically twisted hyphae, 2.5–19 µm diam. (n = 32/3), hyaline or with straw yellow or honey-colored intracellular pigment (in NH 4 OH), thin-walled, septa distant, sub-hymenium with branched hyphae. Pileitrama composed of radially arranged hyphae, 8.7–15 µm diam. (n = 20/1), cylindrical or broadly cylindrical, hyaline, thin-walled, septate. Pileipellis a cutis formed by prostrate and sometimes entangled, cylindrical hyphae, 3.7–12.5 µm diam. (n = 45/3), usually with yellowish brown, brown, straw yellow or hyaline intracellular pigment, sometimes coagulated, thin-walled, septate; terminal hyphae cylindrical with a rounded or slightly clavate apex, prostrate. Stipitipellis a cutis, hyphae cylindrical, 2.5–8.7 µm diam. (n = 20/1), hyaline or straw yellow, thin-walled, septa distant. Caulocystidia absent. Clamp connections present. Refractive hyphae present.

Habitat:—Gregarious, in sandy soil, in the Amazon Forest.

Distribution:—Found to date only in the state of Pará.

Additional material examined:— BRAZIL. Pará: Caxiuanã, Caxiuanã National Forest, EsecaFlor plot, 10 February 2011, F. Karstedt et al. FK1814 (Paratype, SP); 14 February 2011, R. Maziero & M. Tassilo 11RMT126 (Paratype, SP) .

Comments:—The species that most resemble E. amazonicum are E. procerum and E. cervinum , as they have a basidiome with a brown pileus and pale stipe. Apart from the morphological differences between E. amazonicum , E. cervinum and E. procerum , the molecular analysis ( Fig. 3 ) proved the absence of a relationship between them and even suggests that the presence of pseudocystidia is a distinctive characteristic. It differs from Entoloma procerum , originally described with material from New Zealand, in that the latter has basidiospores with elongated angles, cheilocystidia that vary only from cylindrical to clavate, and by the absence of pseudocystidia (Horak 1976a, 2008). E. amazonicum differs from E. cervinum in that the latter has a frequently papillate pileus, the basidiospores have elongated angles and there are no pseudocystidia ( Karstedt & Capelari 2013 as Inocephalus cervinus ).

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 5. Entoloma amazonicum: a–b. basidiospores: a. FK1814; b. FK1815; c–d. basidia: c. FK1815; d. FK1814; e–g. cheilocystidia: e. FK1814; f. FK1815; g. 11RMT126; h. pseudocystidia (FK1814); i. pileipellis (FK1790). Scales: a–h: 10 µm, i: 20 µm.

FIGURE 10. Microphotography of basidiospores in electron microscopy: a–c. Entoloma acutipallidum (11RMT078); d–f. E. amazonicum (FK1815); g–i. E. arenicola (FK1811); j–m. E. capes (FK2096), n–p. E. caxiuanense (FK1871). Scale: 5 µm.

FIGURE 34. Basidiomas: a–b. Entoloma amazonicum: a. FK1815; b. FK1814; c. E. luteobrunneum (FK1693); d. E. gatesianum (ACM498). Photos: a–c: F. Karstedt; d: A.C. Magnago. Scale: 1 cm.