Entoloma acutipallidum

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 : 18-20

Entoloma acutipallidum E. Horak & Cheype, Bull. Soc. Mycol. Fr. 124: 289. 2008.

Figs. 4 , 10a–c , 33a–b

Description:— Pileus 35–55 mm diam., 25–35 mm tall, conical-papillate, brownish beige, yellowish brown to brown at center, slightly hygrophanous, surface strongly adpressed-fibrillose, slightly translucent-striate, margin crenulate, irregular or split, papilla pronounced, concolorous with the surface, not striate, sometimes slightly squamulose-fibrillose. Pileus context thin, translucent, brownish near the margin and white at center. Lamellae free to adnexed, faces smooth, ventricose (<4 mm), close, white, pinkish white to pinkish, with two tiers of lamellulae, margins uneven, concolorous with faces. Stipe 125–150 × 3–6 mm, cylindrical or attenuated upwards, centrally attached, light brownish cream, glabrous, adpressed-fibrillose, striate and twisted, hollow, with white basal tomentum. Stipe context white. Odor indistinct. Taste not observed. Spore print observed on the pileus, pink.

Basidiospores cuboidal with slightly elongated angles, 4-angled in profile view, rarely with 5 angles, excluding the projections (8.7–)10–12.5 × 10–13.7 µm [xm = 10.6 (± 1.04) × 11.35 (± 0.98) µm, Q = 1–1.28, Qm = 1.07 (± 0.07), n = 60/4], including the projections (10–)11.2–13.7 × (11.25–)12.5–13.75 µm [xm = 12.04 (± 0.75) × 12.73 (± 0.63) µm, Q = 1–1.22, Qm = 1.05 (± 0.07), n = 33/3], diagonally 13.7–17.5 × 15–18.7 µm [xm = 14.9 (± 0.4) × 16.1 (± 0.9) µm, Q = 1–1.16, Qm = 1.01 (± 0.02), n = 20/2], diagonally light pinkish brown, thin-walled. Basidia broadly cylindrical or broadly clavate, 46–61(–77) × 12.5–17.5 µm (n = 36/4), hyaline, thin-walled, 4-sterigmate. Cheilocystidia dispersed along the margin of the lamellae, cylindrical, cylindrico-clavate or clavate, hyphoid or branched, (37–)44–112 × 6.5– 13.7 µm (n = 25/3), hyaline, thin-walled. Pleurocystidia and pseudocystidia absent. Lamellar trama formed by parallel, cylindrical or broadly cylindrical hyphae, (3.7–)6.2–24 µm diam. (n = 53/4), hyaline, thin-walled, septate, septa distant (ca. 200 µm apart, n = 2); sub-hymenium branched. Pileitrama composed of radially arranged hyphae, (6.2–)11.2–29 µm diam. (n = 55/4), cylindrical or broadly cylindrical, hyaline or sometimes with a pale brown intracellular pigment, thin-walled, septate. Pileipellis a cutis, 3.7–11.2(–15) µm diam. (n = 57/4), usually with straw yellow intracellular pigment or hyaline, thin-walled, septa distant (ca. 200 µm apart). Stipitipellis formed by prostrate hyphae, cylindrical, sometimes branched, 2.5–8.7 µm diam. (n = 40/3), hyaline or with straw yellow intracellular pigment, thin-walled. Caulocystidia absent. Clamp connections present in all tissues. Refractive hyphae present in the context and in the lamellar trama.

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

Distribution:— Entoloma acutipallidum was originally described from French Guiana ( Horak & Cheype 2008) and recorded from Trinidad [ Dennis 1953, Pegler 1983 as Nolanea pinna (Romagn.) Dennis (1970:77) ]. It is hereby recorded from Belém and Caxiuanã in the state of Pará, Brazil.

Additional material examined:— BRAZIL. Pará: Caxiuanã, Caxiuanã National Forest, Plot PPBio, Trail 2, 19 February 2008, R. Maziero TBGAG649 ( MG); 12 February 2011, R. Maziero & M. Tassilo 11RMT078 ( MG); Belém, Reserva do Mocambo , 22 February 2011, F. Karstedt & E. Castro FK1893 ( SP) . TRINIDAD. Arima: “ Northern Range ”, 25 September 1949, R.W.G. Dennis 46 ( K) .

Comments:— Entoloma acutipallidum resembles Nolanea pinna in that it has a relatively large basidiome with a brownish yellow, conical, papillate, strongly adpressed-fibrillose, striate pileus. However, N. pinna has prismatic, non-cuboidal basidiospores and lacks cheilocystidia (Romagnesi 1941). Dennis (1953). Pegler (1983) considered the basidiospores of the material Dennis 46 to be prismatic, the cystidia to be absent, and thus identified it as Nolanea pinna . Our morphological analysis of the material showed that the basidiospores are cuboidal and cheilocystidia are present and therefore it fits the description of Entoloma acutipallidum . In the phylogenetic analysis ( Fig. 3 ), Entoloma acutipallidum is closely related to species that share a strongly adpressed-fibrillose or squamulose-fibrillose pileal surface, with fibrils and scales that are more pigmented than the surface below them, with basidiospores with slightly elongated angles, or not, and a pileipellis as a cutis in transition to a trichoderm.

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 4. Entoloma acutipallidum: a–d. basidiospores: a. 11RMT078; b. TBGAG649; c. FK1893; d. Dennis 46; e. basidia (11RMT078); f–g. cheilocystidia: f. FK1893; g. TBGAG649; h. pileipellis (TBGAG649). Scales: a–g: 10 µm, h: 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.