Neohygrocybe fumosa J.S. Cardoso, M.A. Neves & J.S. Oliveira, 2023

Cardoso, Juli Simon, Moncalvo, Jean-Marc, Lodge, D. Jean, Margaritescu, Simona, Neves, Maria Alice & Oliveira, Jadson J. S., 2023, Studies in Hygrocybe s. l. (Hygrocyboideae, Hygrophoraceae) in Brazil: New species of Humidicutis and Neohygrocybe, Phytotaxa 607 (1), pp. 57-71 : 64-66

Neohygrocybe fumosa J.S. Cardoso, M.A. Neves & J.S. Oliveira , sp. nov. ( Figs. 3f–h , 4d–f , 5 )

MycoBank # MB844323

Etymology:—From Latin “fumosus” = smoky, grey, changing to brown; refers to the greyish light brown pileus.

Type:— BRAZIL. Mato Grosso: Novo Mundo, Reserva Particular do Patrimônio Natural Cristalino , Castanheira Trail , 250 m elev., 9º33’52’’S 55º54’19’’W, 9 January 2019, Cardoso, J. S. & Furtado , A. N. M. 600 ( FLOR67460 , holotype) .

Diagnosis:—Basidiomata dull-coloured, pileus umbonate, greyish brown, lamellae pale greyish brown, stipe light silvery grey, basidiomata with a distinct nitrous smell and without colour changes when injured. Differs from Neohygrocybe subovina by having brighter colours, no colour changes upon bruising, ellipsoid basidiospores and pyriform cheilocystidia.

Description:— Pileus 30–44 mm diam., plane-convex, umbonate, sometimes tearing in the centre, slightly fibrillose, moist to dry, becoming translucent-striate towards margin, hygrophanous, light grey-brown (oac730, oac729) to brown (oac748, oac749); margin translucent-striate, uplifted to revolute, undulating, eroded, pale grey (oac732). Lamellae uncinate, up to 8mm broad, subdistant, thick, white with shades of grey-brown (oac711, oac718), intervenose, with veins projecting in the lamellar faces; lamellulae of two lengths, anastomosing. Stipe 75–83 × 5–7 mm, central, flexuous, hollow, smooth, glabrous, moist to dry, silky, tapering towards the base, light silvery grey (oac774, oac690) to whitish. Odour nitrous.

Basidiospores 6.8– 7.99 –9.1 × 5.2– 6.08 –7.1 µm, Q = 1.315, ellipsoid, smooth, hyaline, inamyloid, thin-walled, guttulate, hilar appendage visible. Basidia 26.8–36.4 × 6.3–9.7 (–10.8) µm, clavate, thin-walled, hyaline, 2–4-spored, sterigmata up to 7 µm, with basal regular clamp connections. Lamellar edge fertile. Cheilocystidia 32.8–35.6 × 16.6– 22.1 µm, pyriform, like a swollen basidiole, sometimes guttulate. Pleurocystidia absent. Pseudocystidia 96.7–219.3 × 15.1–23.6 µm, obclavate to ventricose-rostrate, apex sometimes with conspicuous cellular contents, emerging from the lamellar trama and projecting up to 40 µm above basidia and basidioles ( Figure 5 ). Lamellar trama regular, composed of parallel inflated elements, 40.2–233.2 × 8.6–33.8 µm, clamp connections present. Pileipellis a cutis, with parallel, undifferentiated hyphae, 3.3–7 µm diam., some with granular encrusting pigments, pale brownish in water, hyaline in KOH, clamp connections present. Stipitipellis a cutis, hyphae 2.3–15.9 µm diam., hyaline in KOH and water, with rare encrustations, clamp connections present.

Specimens examined:— BRAZIL. Mato Grosso: Alta Floresta , RPPN Cristalino, Dr. Haffer’s Trail, 250 m elev., 9º3”10’ S 55 º54”53’ W , 25 January 2018, Cardoso , J. S . 277 ( FLOR63574 ); Novo Mundo , RPPN Cristalino, Castanheira Trail, 250 m elev., 9º33’52’’S 55º54’19’’W, 9 January 2019, Cardoso , J. S . & Furtado, A. N. M . 600 ( FLOR67460 ) .

Distribution:—Known only from the type locality.

Habitat:—Growing solitary on clay soils of terra-firme forest.

Comments:— Neohygrocybe fumosa is the first species of the genus described from Brazil. There are two species known from the neotropical region: Neohygrocybe subovina (Hesler & A.H. Sm.) Lodge & Padamsee (2013 [2014]: 41) and Hygrocybe ovinoides Lodge, S.A. Cantrell & T.J. Baroni (2004: 1312) combined in Neohygrocybe herein. Neohygrocybe subovina , from USA, also has cheilocystidia and pseudocystidia projecting from the hymenium, but the basidiomata are much darker in colour, the lamellae bruise pink to reddish brown or darker, the basidiospores are globose to subglobose rather than ellipsoid, and the cheilocystidia are vermiform and cylindrical rather than pyriform ( Hesler & Smith 1963). Hygrocybe ovinoides produces very small basidiomata which are also dark in colour, but the pilei have a white margin ( Cantrell & Lodge 2004). In the microscopy, H. ovinoides lacks cheilocystidia and has hook-like pileocystidia ( Cantrell & Lodge 2004). Both N. subovina and H. ovinoides lack the nitrous odour found in N. fumosa .

Figures

FIGURE 3. a, b, c, d, e. Humidicutis pindorama; a, b, c. JS485; d, e. JS18. f, g, h. Neohygrocybe fumosa (JS600). Scale = 10mm. Photos a, b, c, f, g, h by J.S. Cardoso; d, e by M.A. Neves.

FIGURE 4. a, b, c. Humidicutis pindorama (JS485). a. basidiospores, b. basidia, c. lamellar trama hyphae. d, e, f. Neohygrocybe fumosa (JS600). d. basidiospores, e. basidia, f. cheilocystidia. Scale = 10 μm. Drawings by: J. S. Cardoso

FIGURE 5. Detail of the lamellar trama showing the pseudocystidia emerging from the hymenium of N. fumosa (JS600). Scale = 50µm. Photo by: J. S. Cardoso