Hohenbuehelia nakhonphanomensis Somrith., S. Sommai, P. Khamsuntorn & U. Pinruan, 2025

Somrithipol, Sayanh, Pinruan, Umpawa, Sommai, Sujinda, Khamsuntorn, Phongsawat & Luangsa-Ard, J. Jennifer, 2025, A new species of Hohenbuehelia in Nakhon Phanom, northeastern Thailand, Phytotaxa 683 (1), pp. 25-39 : 31-34

Hohenbuehelia nakhonphanomensis Somrith., S. Sommai, P. Khamsuntorn & U. Pinruan sp. nov. ( Figs. 3–5 )

Facesoffungi number: FoF13374, Mycobank number: MB846060 Etymology:—Refer to Nakhon Phanom, the province where the holotype was collected.

Diagnosis: —differs from other Hohenbuehelia species in its morphological characteristics of the whitish pileus, subglobose to obovoid basidiospores, and thick-walled cystidia without encrusted crystals that are incorporated in the pileipellis layer of the pileus (pileolamprocystidia) and embedded in the hymenium at the edge (cheilolamprocystidia) and the side (pleurolamprocystidia) of a lamella beside the larger, crystal-encrusted metuloids projecting from the hymenium.

Holotype:— Thailand, Nakhon Phanom Province, Pla Pak District, Nong Hi dry dipterocarp forest, on the dead trunk of a Dipterocarpus sp. , 11 July 2019, BBH47869 .

Description:—Basidiomata leathery, flabelliform, laterally attached to the substratum, 30 mm broad × 25 mm high. Pileus white (N155C–D), paler toward the margin; pileus margin rolled to incurved; surface light yellowish orange (159A). Lamellae white (NN155A) to light yellow orange (159D) turning to light brown (165B) when dried, broad, average, subdistant, entire, unequal. Stipes reduced to pseudostipes, 7–8 mm long, 6–7 mm wide, composed of thin-walled (2.5 μm wide) and thick-walled (up to 5 μm wide) portions, branched hyphae with clamp connections, Context white to cream, soft, thin, up to 7 mm wide. Odor mild.

Basidiospores (5.8–) 6.25–10.0 (–10.5) × 5.0–7.5 µm (L m = 7.95±0.91, W m = 6.40±0.81, n =70) Q = 1.00–1.50– 1.68, Q m = 1.26, subglobose to obovoid, smooth- and thin-walled, inamyloid, hyaline with granular content. Basidia (20–) 23–27 (–31.3) × (3.8–) 6.3–7.5 (–10) µm, clavate, thin-walled, hyaline, occurring on edge and side of lamella, with 2–4 sterigmata of 2.5–7.5 μm long. Cheilocystidia of three distinct types: (1) metuloid type (cheilometuloids) (40–) 47.5–82.5 × (11.3–) 12.5–15.0 (–17.5) μm, fusoid to lanceolate or clavate to spatulate with an attenuate apex, covered partly with refractive encrusted crystals, thick-walled (2.5–6.25 μm of wall thickness) with a cell lumen (5.0–12.5 μm wide), isolated or in groups at the lamellar edge, prominently projecting from the hymenium; (2) lamprocystidium type (cheilolamprocystidia) 30–42.5 × 5–7.5 μm, fusiform to bowling-pin-shaped, without encrusted crystals covering, smooth- and thick-walled (2.5–3.75 μm of wall thickness) with a narrow cell lumen (1.25–5 μm wide), isolated, embedded in the hymenium; (3) leptocystidium type (cheiloleptocystidia) 17.5–25.0 × 3.8–5.0 μm, flask-shaped with a short or long neck tapering into a capitellum capped with a drop of mucus, smooth- and thin-walled. Pleurocystidia dimorphic, of two distinct types: (1) metuloid type (pleurometuloids) 55–97.5 × 12.5–20 μm, fusoid to lanceolate, covered partly with refractive encrusted crystals, thick-walled (2.5–7.5 μm of wall thickness) with a cell lumen (2.5–10 μm wide), isolated, prominently projecting from the hymenium along the lamellar side; (2) lamprocystidium type (pleurolamprocyctidia) 27.5–50 × 5–7.5 (–10) μm, narrowly lageniform to bowling-pin-shaped, without encrusted crystals covering, smooth- and thick-walled (2.5–3.75 μm of wall thickness) with a narrow cell lumen (1.25–5 μm wide), isolated, embedded in the hymenium. Hymenophoral trama subregular, 62.5–250 μm thick. Pileus trama composed of interwoven, thin-walled, hyaline, septate, branched, 2–2.5 μm wide hyphae with clamp connections. Pileipellis composed of interrupted ixocutis of septate, thin-walled, hyaline 3–5 μm wide hyphae with clamp connection. Trichodermial elements (Pileolamprocystidia) 60–100 × 6.3–7.5 μm, isolated, smooth- and thick-walled (2.5–3.75 μm of wall thickness) with a very narrow cell lumen and without encrusted crystals. Tomentose or hispidulous layer 83–375 μm thick, composed of thin-walled, hyaline, 2.5–4.5 μm wide hyphae with clamp connections, erected from the epicutis. Gelatinous subpellis 425–525 μm thick, composed of interwoven, thin-walled, hyaline, septate, branched, 1.3–5 μm wide hyphae with clamp connection.

Additional specimen examined:— Thailand, Nakhon Phanom Province, Pla Pak District, Nong Hi dry dipterocarp forest, on the dead trunk, 11 July 2019, BBH49789.

Figures

FIGURE 3. Hohenbuehelia nakhonphanomensis (BBH47869, holotype). a. Pileus. b. Lamella. c. Tomentose or hispidulous layer. d. Pileipellis with pileolamprocystidia (arrowed). e. Gelatinous subpellis. f. Hyphae of gelatinous subpellis. g–h. Basidiospores. i–k. Basidia. Scale bars: a, b =10 mm; c, e= 100 μm; d= 20 μm; f= 50 μm; g–k= 10 μm.

FIGURE 4. Hohenbuehelia nakhonphanomensis (BBH47869, holotype)- cystidia. a–c. Pleurometuloids and encrusted crystals (arrowed). d–e. Pleurolamprocystidia. f–i. Cheilometuloids and encrusted crystals (arrowed). j. Cheilolamprocystidia k–l. Cheiloleptocystidia with a neck tapering into a capitellum capped with a drop of mucus (arrowed). Scale bars: a, f, g = 25 μm; b–e, h–l= 10 μm.

FIGURE 5. Line drawings of Hohenbuehelia nakhonphanomensis (BBH47869, holotype) a. A diagrammatic section of a basidiomata. b. Terminal cell of the pileipellis hyphae. c. Pileipellis hyphae with clamp connections. d. Pileolamprocystidia. e. Basidiospores. f. Basidia. g. Pleurometuloids. h. Pleurolamprocystidia. i. Cheilometuloids. j. Cheilolamprocystidia. k. Cheiloleptocystidia. Scale bars: a =100 μm; b–k= 25 μm.