Mycena discogena Singer (1962a: 388)

Cooper, Alexandra C., Desjardin, Dennis E. & Perry, Brian A., 2018, The genus Mycena (Basidiomycota, Agaricales, Mycenaceae) and allied genera from Republic of São Tomé and Príncipe, West Africa, Phytotaxa 383 (1), pp. 1-47 : 28-29

11. Mycena discogena Singer (1962a: 388) ( Fig. 21 )

Description:— Pileus 3–4 mm diam, convex, striate to sulcate; surface dull, dry, glabrous, disc with brownish tones, pale ash white elsewhere. Lamellae ascending, forming a pseudocollarium, subdistant with 2 series of lamellulae, white. Stipe 20–22 × 0.5 mm, central, terete, cylindrical, arising from a small, white tomentose basal disc; surface dull, dry, minutely white-puberulous, ash white, developing brown tones towards the base. Odour and taste not recorded. Bioluminescence undetected.

Basidiospores (6.4–)7.2–8.5 × 4.0–4.8 μm [x m = 7.40 ± 0.44 × 4.36 ± 0.41 μm, Q = 1.50–2.00, Q m = 1.71 ± 0.19, n = 20, s = 1], ellipsoid, smooth, hyaline, amyloid, thin-walled. Basidia 17.6–19.2 × 6.4–8 μm, clavate, hyaline, inamyloid, thin-walled, 4-spored, sterigmata up to 3 μm long. Basidioles clavate. Lamellar edge sterile. Cheilocystidia numerous, 19.2–26.4 × 9.6–12 μm, clavate, spinulose over upper half, hyaline, inamyloid; spinulae 0.8–1.6 × 0.8– 1.6 μm. Pleurocystidia absent. Pileipellis a hymeniform layer of acanthocysts; 17.6–26 × 10.4–28 μm, globose to broadly clavate, densely spinulose, hyaline, inamyloid to weakly dextrinoid, thin-walled; spinulae 0.5–0.8 × 0.5–0.8 μm Hypodermium composed of inflated hyphae up to 33 μm diam, ovoid to globose, hyaline, dextrinoid, thin-walled. Hymenophoral trama regular to subregular; hyphae 6.4–23 μm diam, hyaline, dextrinoid, non-gelatinous, thin-walled. Stipitipellis a cutis; cortical hyphae 2.4–8.8 μm diam, parallel, cylindrical, smooth, hyaline, dextrinoid, thin-walled; medullary hyphae 13.6–23 μm diam, smooth, hyaline, dextrinoid, thin-walled, occasional laticiferous hyphae 2.4–4 μm diam with knob-like projections. Caulocystidia abundant, scattered to clustered, 25–96 × 6.4–17 μm, cylindrical to fusiform-acuminate, smooth, hyaline, inamyloid, thin-walled. Basal disc cystidia 36–90 × 6.5–20 μm, clavate to fusiform or cylindrical, narrowing to an acute tip, non-diverticulate, hyaline, inamyloid, thin-walled. Clamp connections present in all tissues.

Habitat and known distribution:—Gregarious on sticks in secondary coastal forest. Africa ( Príncipe); Chile (Juan Fernández Islands).

Material examined:—AFRICA. Príncipe, Dois Irmãos area, N01˚34.889’, E07˚25.548’, 23 April 2008, D.E. Desjardin and B.A. Perry, BAP 649 (SFSU).

Notes:— Mycena discogena is distinguished by a small, greyish brown to ash white, striate pileus, white, pseudocollariate, subdistant lamellae, a white, puberulous stipe that arises from a small basal disc, basidiospores with mean 7.4 × 4.4 μm, clavate, spinulose cheilocystidia, no pleurocystidia, a hymeniform pileipellis of spinulose globose acanthocysts, non-spinulose, fusiform-acuminate caulocystidia and basal disc cystidia, and growth on sticks. In combination, these features indicate placement in sect. Sacchariferae , stirps Adscendens . The species was described from material collected on the Juan Fernández Islands, Chile, and according to the description, differs from the material from Príncipe only in forming slightly broader basidiospores with mean 8.3 × 5.3 μm (Singer 1962 a, Desjardin 1995).

Pairwise comparisons of aligned, overlapping ITS sequences of the Príncipe specimen (BAP 649) with the top ten BLAST results show 92.3–93.1% similarity to seven uncultured Mycena clones (but only 61% query coverage). Mycena discogena falls in a heterogeneous clade with members of sects. Exornatae , Polyadelphia , Granuliferae , Longisetae and Sacchariferae in the ITS phylogeny ( Fig. 2).

Figures

FIGURE 21. Mycena discogena (BAP 649). a. Basidiospores. b. Basidia. c. Cheilocystidia. d. Acanthocysts. e. Caulocystidia. f. Basal disc cystidia. Scale bar = 10 μm.