Entoloma caxiuanense 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 : 28-30

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).

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 9. Entoloma caxiuanense (FK1871): a. basidiospores; b. basidia; c. cheilocystidia; d. pileipellis. Scales: a–c: 10 µm, d: 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 33. Basidiomas:a–b. Entoloma acutipallidum: a. FK1893; b. 11RMT078; c. E. caxiuanense (FK1871); d. E. dennisii (CP47/04); e–g. E. luteolamellatum: e. 11RMT094; f–g. 11RMT109; h. E. capes (FK2096). Photos: a, c, h: F. Karstedt; b, e–g: R. Mazieiro; d: C. Puccinelli. Scale: 1 cm.