Entoloma caxiuanense Karstedt & Capelari, sp. nov.
Creators: name: Karstedt, Fernanda
name: Bergemann, Sarah E.
name: Gates, Genevieve
name: Ratkowsky, David
name: Cunha, Kelmer Martins
name: Capelari, Marina
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Entolomataceae
Entoloma
Entoloma caxiuanense

description: Entoloma caxiuanense Karstedt & Capelari, sp. nov.
Figs. 9, 10n–p, 33c
MB 838589
Etymology:— Caxiuanense refers to the Caxiuanã National Forest where the species was collected.
Diagnosis:— Entoloma caxiuanense is characterised by the combination of a conical, squamulose pileus, cheilocystidia along the entire lamellar margin, a cutis in transition to a trichoderm, and small basidiospores [xm = 6.34 (± 0.31) × 6.67 (± 0.6) µm] which differentiate it from all other species included in this study.
Type:— BRAZIL. Pará: Caxiuanã, Caxiuanã National Forest, Ferreira Penha Station, Plot 1, 15 February 2011, F. Karstedt et al. FK1871 (Holotype, SP).
Description:— Pileus to 40 mm diam., broadly conical, margin slightly revolute, slightly translucent-striate, center brown, fibrils brownish and surface slightly yellowish beige, not hygrophanous; fibrillose or squamose, with scales more abundant in the center of the pileus than on the margin. Pileus context not observed. Lamellae adnate or sinuate, smooth, ventricose, pale yellow-pink, close with two tiers of lamellulae, margins irregular and concolorous with faces. Stipe 80 × 4–6 mm, slightly attenuated above, circular or flattened in cross-section, centrally attached, slightly yellowcream, fibrillose, surface slightly striate and twisted, hollow, with a small amount of white basal tomentum. Stipe context not observed. Odor and taste not observed. Spore print not observed.
Basidiospores cuboidal, 4-angled in profile view, 6.2–7(–7.5) × 6.2–7.5 µm [xm = 6.34 (± 0.31) × 6.67 (± 0.6) µm, Q = 1–1.2, Qm = 1.05 (± 0.08), n = 21/1] in profile view and diagonally (6.2–)7.5–8.7 × 7.5–8.75 µm [xm = 7.62 (± 0.54) × 7.88 (± 0.57) µm, Q = 1–1.16, Qm = 1.04 (± 0.07), n = 21], thin-walled. Basidia clavate-pedicellate, 33–51 × 10–112.5 µm (n = 13), hyaline, thin-walled, with 4 long sterigmata. Cheilocystidia abundant, along the entire lamellar margin, cylindrical or cylindro-clavate, 30–125 × 6.2–15 µm (n = 24), hyaline, thin-walled. Pleurocystidia and pseudocystidia absent. Lamellar trama of parallel, cylindrical or broadly cylindrical hyphae, 3.7–16 µm diam. (n = 20), hyaline, thin-walled, septa rare, sub-hymenium not observed. Pileitrama composed of radially arranged hyphae, cylindrical or broadly cylindrical, 5–22 µm diam. (n = 20), hyaline, thin-walled, septa rare. Pileipellis a trichoderm or groups of anticlinal terminal hyphae in transition to a trichoderm; prostrate hyphae cylindrical, 8.7–15 µm diam. (n = 14), with brown intracellular pigment or, less frequently, hyaline; anticlinal hyphae cylindrical, broadly cylindrical or clavate, with or without septa, 50–300 × 11.2–16.2 µm (n = 10), with brown or hyaline intracellular pigment, thin-walled. Stipitipellis a cutis with cylindrical hyphae, 5–10 µm diam. (n = 20), hyaline or with straw yellow intracellular pigment, thin-walled, septate. Caulocystidia absent. Clamp connections present. Refractive hyphae present.
Habitat:—Solitary, in soil with organic matter and roots, in the Amazon Forest biome.
Distribution:—Only known from Pará, Brazil.
Comments:—This species would traditionally be classified in Leptonia, due to the structure of the pileipellis. However, by phylogenetic analysis (Fig. 3) it is possible to verify that this species is included in the clade with the other species having cuboidal basidiospores (Entoloma subg. Cubospora) and not in one of the clades with Leptonia species, thus lending further support to the notion that the shape of the basidiospores is a more relevant feature than the structure of the pileipellis.
Entoloma cuboidosporum (Beeli) E. Horak, the species that most resembles E. caxiuanense, is characterized by small, cuboidal basidiospores (5.5–7.5 µm), cheilocystidia forming a sterile margin and a pileipellis between a cutis and a trichoderm. However, they differ in that E. cuboidosporum has a depressed, infundibuliform center with an amber brown color, decurrent lamellae, and clavate to vesiculose cheilocystidia (Horak 1976a).
description: Published as part of Karstedt, Fernanda, Bergemann, Sarah E., Gates, Genevieve, Ratkowsky, David, Cunha, Kelmer Martins & Capelari, Marina, 2024, Species of Entoloma (Entolomataceae) with cuboidal basidiospores from Brazil, pp. 1-76 in Phytotaxa 654 (1) on pages 28-30, DOI: 10.11646/phytotaxa.654.1.1, http://zenodo.org/record/13217065