Entoloma viscaurantium

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 : 61-63

Entoloma viscaurantium E. Horak & Singer, Sydowia 35: 81. 1982.

Figs. 30 , 32d–g

Description:— Pileus 22 mm diam., distinctly conical or papillate, then becoming campanulate or convex-umbonate, brown to orange-brown in the center, cinnamon-orange or pink-orange towards the margin, viscid, glabrous, margin crenate, translucent-striate. Pileus context pale orange-brown. Lamellae adnate, subdistant, pinkish orange to pale brownish orange; margins fimbriate, concolorous with faces. Stipe 30 × 2 mm, cylindrical, regular, concolorous with the pileus or orange, smooth, non-viscid, solid, simple. Odor and taste indistinct.

Basidiospores cuboidal with slightly elongated angles, 4-angled in profile view, rarely 3-angled, excluding the projections (7.5–)8.7–10(–11.25) × 8.7–11.2 µm [xm = 9.03 (± 0.75) × 9.9 (± 0.7) µm, Q = 1–1.29(–1.33), Qm = 1.1 (± 0.1), n = 40], including the projections (8.7–)10–12.5 × 10–13.7 µm [xm = 10.55 (± 0.8) × 11.6 (± 0.88) µm, Q = 1–1.25(–1.4), Qm = 1.1 (± 0.1), n = 40], and diagonally 12.5–13.7(–15) × 12.5–15 µm [xm = 12.11 (± 0.8) × 13.59 (± 0.9) µm, Q = 1–1.22(–1.33), Qm = 1.09 (± 0.08), n = 40], thin-walled. Basidia clavate, 39–50 × 10–16 µm (n = 20), with honey-colored or brownish intracellular pigment, walls slightly thickened, 4-sterigmate. Cheilocystidia abundant, along the entire lamellar margin, cylindrical, cylindro-clavate, clavate, napiform, ventricose or branched, 40–100 × 7.5–16 µm (n = 20), hyaline or with a little straw yellow intracellular pigment, thin-walled. Pleurocystidia absent. Pseudocystidia cylindrical, ventricose or fusoid, 3.7–8.7 µm diam. (n = 20), lightly or heavily pigmented with straw yellow or honey-colored intracellular pigment, walls slightly thickened. Lamellar trama of parallel, cylindrical or sometimes inflated hyphae, 3.7–24 µm diam. (n = 20), hyaline or with straw yellow intracellular pigment, thin-walled, septate (distance between septa about 200 µm); sub-hymenium branched. Pileitrama composed of radially arranged hyphae, 3.7–20 µm diam. (n = 20), cylindrical, broadly cylindrical or irregular, hyaline or with little straw yellow or honey-colored intracellular pigment, walls thin or slightly thickened, septate. Pileipellis a cutis formed by slightly entangled, prostrate, cylindrical hyphae, 3.7–8.7 (–12.5) µm diam. (n = 20), hyaline or with straw yellow intracellular pigment, thin-walled or slightly thickened, septate. Stipitipellis a cutis, hyphae cylindrical, 3.7–7.5 µm diam. (n = 20), hyaline or with straw yellow or honey-colored intracellular pigment, walls thin or slightly thickened, septate. Caulocystidia absent. Clamp connections present in all tissues. Refractive hyphae present, honey-colored.

Habitat:—Solitary, in soil or among litter, in the Amazon Forest biome.

Distribution:—To date collected only in Amazonas ( Horak 1982).

Material Examined :— BRAZIL. Amazonas : Manaus , Ponta Negra (Rio Negro), 24 December 1978, R. Singer B 11442, ZT 80/147 (Isotype, ZT) .

Comments:—The holotype of Entoloma viscaurantium deposited in the INPA herbarium (81197) was not found. The isotype is composed of a single basidiome, with the pileus divided into three parts, the largest 13 mm wide, with an apparently smooth and striate surface at the insertion of the lamellae. The lamellae are adnate or adnexed, ventricose, the margin is slightly faded in relation to the faces and is slightly irregular. The stipe is apparently cylindrical, measuring 23 mm long, hollow and flattened. The macroscopic description presented here is that of Horak (1982) and the microscopic description was carried out on the isotype.

Entoloma viscaurantium is characterized by a viscid, brown to orange (at the centre) pileus, pink-orange to pale orange-brown lamellae concolorous with the pileus or completely orange, cuboidal basidiospores and the presence of pseudocystidia and cheilocystidia. Horak (1982) mentioned in the protologue that the basidiospores are contorted cuboids; however, the microscopic examination of the isotype demonstrated that the basidiospores are not exactly as described by Horak (1982). The observed basidiospores are more irregular, at times it appears that one of the angles is absent as if two sides of the cube formed only one side by the loss of one of the edges. Another difference was the observation of the existence of pseudocystidia that was not reported by Horak (1982).

The morphological characteristics as described in Horak (1982) suggest that Entoloma viscaurantium is related to E. dragoluteum and E. dragorufescens , having a conical or papillate translucent-striate pileus, a pigmented pileus and stipe, and cuboid-stellate basidiospores. However, neither E. dragoluteum nor E. dragorufescens have pseudocystidia and pigmented refractive hyphae. These last two characteristics relate E. viscaurantium with species from the /Psittacini subclade. The only species of this subclade with a brownish pileus is E. amazonicum , which differs in having a whitish stipe, in addition to smaller cuboidal basidiospores with angles rarely slightly elongated, measuring 7.5–10 × 8.7–11.2 µm. Another species that can be related is E. gatesianum , which, however, differs by the fusoid or fusoid-ampuliform cheilocystidia.

The color of the basidiome tending to orange, the conical pileus shape and the shape and size of the cheilocystidia relate this species to Entoloma lycopersicum . However, these species differ by the pileus surface, which is viscid in E. viscaurantium and dry in E. lycopersicum ; and slightly in the shape of the basidiospores; in E. viscaurantium the angles are elongated and in E. lycopersicum they are not, or are only very slightly, elongated. Pseudocystidia are also present in E. viscaurantium whereas they are absent in E. lycopersicum .

The attempts to obtain DNA sequences were unsuccessful.

Figures

FIGURE 30. Entoloma viscaurantium (Singer B11442): a. basidiospores; b. basidia; c. pseudocystidia; d. cheilocystidia. Scale: 10 µm.

FIGURE 32. Microphotography of basidiospores in electron microscopy: a–c. E. vinososquamulosum (FK1745); d–g. E. viscaurantium (Singer B11442); h–j. E. voltavelhense (FK1694). Scale: 5 µm.