Rhodocollybia maculata

Ryoo, Rhim, Ka, Kang-Hyeon & Antonín, Vladimír, 2024, The genus Rhodocollybia (Omphalotaceae, Basidiomycota) in the Republic of Korea, Phytotaxa 642 (2), pp. 111-126 : 115-117

Rhodocollybia maculata (Alb. & Schwein.: Fr.) Singer Figs. 3A , 4A‒C

Description:— Pileus 25‒65 mm broad, broadly conical to convex-conical, mostly with broad low umbo and inflexed margin, slightly greasy when moist, not translucently striate, slightly or not hygrophanous, white, milky white, sometimes with rusty brownish tinge, rusty stained, especially in old specimens. Lamellae close, L = 60‒65, l = 3‒4, sinuate and attached with small tooth, almost free when old, pale cream, later yellowish cream (±3A2), edge finely serrulate, concolorous with faces. Stipe 35‒75 × 4‒7 mm, cylindrical, slightly broadened at apex, not or only slightly broadened at base, finely longitudinally striate-fibrillose, glabrous, white with rusty orange-tinged base, with scattered rusty stains, especially in lower part, when old; basal rhizoids rusty orange. Context watery white, hollow in stipe, with fungoid smell and very unpleasant bitter taste.

Basidiospores (5.0‒) 5.5‒6.5 × 4.0‒5.3 (‒5.5) µm, average 5.83 × 4.70 µm, E = 1.10‒1.35 (‒1.53), Q = 1.25, ellipsoid, broadly ellipsoid or rarely subglobose or dacryoid, both types of spores, thin-walled and non-dextrinoid, and slightly thick-walled and dextrinoid, present. Basidia 25‒30 × 8.0‒9.0 µm, 4-spored, clavate. Basidioles 15‒ 30 × 3.0‒9.0 µm, clavate, cylindrical, subfusoid. Cheilocystidia 26‒33 × 4.5‒8.0 µm, cylindrical, fusoid or clavate, irregular, branched to coralloid, thin-walled. Trama hyphae of cylindrical or fusoid cells, thin-walled, non-dextrinoid, 3.0‒10 µm wide. Pileipellis an ixocutis, composed of cylindrical, radially arranged, thin-walled hyphae 2.5‒7.0 µm wide; terminal cells adpressed to suberect, mostly cylindrical, thin-walled, 2.0‒4.0 µm wide. Stipitipellis a cutis of cylindrical, slightly thick-walled hyphae 2.5‒5.0 µm wide arranged in parallel. Caulocystidia (apex) infrequent, often in the form of terminal cells or lateral projections, adpressed to erect, 19‒50 × 4.0‒8.0 µm, cylindrical, narrowly clavate, subfusoid to fusoid, obtuse, thin-walled. Clamp connections present in all tissues.

Ecology:—On soil, in mixed forest under Carpinus laxiflora , Pinus densiflora and Quercus sp.

Specimen examined:— REPUBLIC OF KOREA. Jeollabuk-do, Jangsu-gun, Waryong National Recreational Forest, 6 September 2016, V. Antonín 16.157 & R. Ryoo (BRNM 840489).

Remarks:— Rhodocollybia maculata is characterized by a pileus not translucently striate, milky white, sometimes rusty brownish tinged, rusty stained, lamellae close, a stipe that is cylindrical, white, basally rusty orange-tinged with scattered stains. Basidiospores are (5.0‒) 5.5‒6.5 × 4.0‒5.3 (‒5.5) µm, ellipsoid, broadly ellipsoid, rarely subglobose, and cheilocystidia 26‒33 × 4.5‒8.0 µm, cylindrical, fusoid or clavate, irregular, branched to coralloid.

The Korean collection of Rhodocollybia maculata is macro- and micromorphologically very similar to European material. It differs only in smaller and less fleshy basidiomata; all other characters fit into the species variability ( Antonín & Noordeloos 2010). Among the close species, Rhodocollybia lignitilis J. L. Mata & Halling (in Mata et al. 2004: 342) is similar by developing brown to reddish brown irregular spots when bruised. It differs by a pileus that is at first light brown to butter yellow, pale orange, and in age cinnamon brown, a dark orange-brown stipe, longer basidia (24–43 × 5–8 mm), slightly different basidiospores, 5.2–7.2 × 3.2–4.8 μm, Q = 1.57, and grows directly on wood ( Mata et al. 2004); R. turpis ( Halling 1989: 870) Halling (in Antonín et al. 1997: 366) differs by a light yellow pileus when young, becoming pale orange with brown spots and streaks, a context when fresh staining rufescent orange within 2‒3 minutes of exposure and becoming dark grey to black when dried, and smaller basidiospores, 4.9‒6.7 × 3.5‒4.2 µm, Q = 1.58 ( Halling 1989); R. laulaha Desjardin, Halling & Hemmes (1999: 167) has a light brown to brown pileus overall when young, remaining so in flecks or fading to light brown, light brownish orange, pale brownish grey or paler to greyish orange, finally fading to orange-white, pale yellowish white or cream buff, often with brown to pale reddish brown spots scattered over the pileus, a pale orange-white to pale reddish white stipe when young, becoming pale brownish grey in age, and smaller, (5.3‒) 5.5‒7.0 × 3.5‒4.5 µm, Q = 1.55, basidiospores ( Desjardin et al. 1999); R. popayanica ( Halling 1989: 872) Halling (in Antonín et al. 1997: 365) differs by a usually pale reddish to pinkish pileus at the disc, white at margin, becoming pale brown with age and smaller, distinctly ellipsoid basidiospores, 6.3‒7.7 × 3.5‒4 µm, Q = 2.05 ( Halling 1989, Villarruel-Ordaz & Cifuentes 2015); R. unakensis ( Murrill 1916: 366) Halling (in Antonín et al. 1997: 366) has an at first a violet-brown pileus, fading to fawn brown or greyish red on the disc and darker toward the margin and smaller, more ellipsoid basidiospores, 5.5‒7 × 3‒4.5 µm ( Halling 1997); R. clavipes ( Corner 1996: 42) Desjardin & Keirle (in Keirle et al. 2010: 469) differs by a fawn, rich fawn tan or subrufous pileus, smaller basidiospores, 4‒5.5 × 2.5‒3 µm, and large, up to 110 × 3.5‒6 µm, caulocystidia ( Corner 1996).

Figures

FIGURE 3. BasidiomataA. Rhodocollybia maculata (BRNM 840489).B. R. butyraceoides (BRNM 840485).C. R. butyraceoides (BRNM 840490, holotype). D. R. variabilicolor (BRNM 718751). E. R. variabilicolor (BRNM 840482). F. R. variabilicolor (BRNM 840488). G. R. variabilicolor (BRNM 840491, holotype). H. R. hongneungensis (BRNM 718721, holotype). Photos by: V. Antonín.

FIGURE 4. Rhodocollybia maculata (BRNM 840489). A. Cheilocystidia. B. Basidiospores. C. Pileipellis. Scale bar = 20 µm. Drawings by V. Antonín and R. Ryoo.