Mycena galopus (Persoon 1800: 56) P. Kummer (1871: 108)

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 : 19-21

6. Mycena galopus (Persoon 1800: 56) P. Kummer (1871: 108) ( Figs. 12 , 13 )

Description:— Pileus 7–13 mm diam, parabolic with upturned margin to campanulate, striate; surface moist, glabrous, disc and striations dark brown (5–6F6–7), fading to light brown (3–4E5–6), pale brownish grey (4C–D3–4) between striations and towards the pale grey margin. Context thin; concolorous with the pileus. Lamellae ascending-adnate with a short decurrent tooth, subdistant (13–14) with 1–2 series of lamellulae, pale grey with upper portion taking on darker tones; edge concolorous. Stipe 35–60 × 1–1.5 mm, central, terete, enlarged slightly towards base, hollow; surface smooth, glabrous, apex pale grey, greyish brown below (3–4D–E4–5), base with white tomentum; latex not observed. Odour and taste indistinct. Bioluminescence undetected.

Basidiospores 8.0–8.8 × (4.0–) 4.8–5.6 μm [x m = 8.32 ± 0.40 × 4.88 ± 0.36 μm, Q = 1.57–2.00, Q m = 1.71 ± 0.09, n = 20, s = 1], ellipsoid, smooth, hyaline, amyloid, thin-walled. Basidia 25–31 × 6.4–8.8 μm, clavate, hyaline, inamyloid, thin-walled, 4-spored, rarely 2-spored, sterigmata up to 9.6 μm long. Basidioles clavate. Cheilocystidia abundant, 57–80 × 11.2–15 μm, fusiform to narrowly lageniform, acute, occasionally with 1 or more apical projections, hyaline, inamyloid, thin-walled. Pleurocystidia common, similar to cheilocystidia, projecting up to 56 μm beyond basidioles. Pileipellis a cutis; hyphae 0.8–2.4 μm diam, repent, cylindrical, irregularly diverticulate with finger-like projections, hyaline, inamyloid, thin-walled, non-gelatinous; diverticula 6.4–22 × 1.6–2.4 μm, cylindrical. Hypodermium of inflated hyphae up to 37 μm diam, ovoid to globose, hyaline, dextrinoid, thin-walled. Hymenophoral trama regular to subregular; hyphae 4.0–9.6 μm diam, hyaline, dextrinoid, non-gelatinous, thin-walled. Stipitipellis a cutis; cortical hyphae 2.4–6.4 μm diam, parallel, cylindrical, diverticulate with finger-like projections, hyaline, inamyloid, thin-walled; diverticula 2.4–8.8 × 1.6–2.4 μm, cylindrical; medullary hyphae 2.4–8 μm diam, smooth, dextrinoid, thin-walled; interspersed with laticiferous hyphae up to 7.2 μm diam with knob-like projections, occasionally with brown granular contents. Caulocystidia absent. Clamp connections present in all tissues.

Habitat and known distribution:—Gregarious and scattered on soil and woody debris in upland forest. Widespread globally; Africa ( São Tomé).

Material examined:—AFRICA. São Tomé, Macambrara radio antenna area, elevation 1300 m, N00˚16.557’, E06˚36.326’, 11 April 2008, D.E. Desjardin and B.A. Perry, BAP 593 (SFSU).

Notes:—The São Tomé specimen of Mycena galopus is characterized by a brown to pale brownish grey, striate pileus, pale grey, ascending-adnate lamellae, a glabrous, greyish brown stipe, an indistinct odour and taste, basidiospores with mean 8.3 × 4.9 μm, acutely fusiform cheilocystidia and pleurocystidia, occasionally with one or more apical projections, a cutis-type pileipellis with long diverticula, clamp connections, diverticulate stipe cortical hyphae, no caulocystidia and growth on woody debris. White latex was not observed in the rather old basidiomata (6) of the single collection, although morphology and ITS data indicate this specimen represents M. galopus . In addition, the basidiospores were significantly shorter than those reported from European material, viz., 8.0–8.8 × (4.0–) 4.8–5.6 μm versus 9.5–14 × 5–6.3 μm ( Maas Geesteranus 1988a, Robich 2003). The São Tomé material would key to M. alcalina (Fr.) Kummer , as reported from East Africa by Pegler (1977) except for the lack of a strong alkaline or nitrous odour, and the much larger hymenial cystidia in M. galopus . The São Tomé specimen shows similarities to M. subcana A.H. Sm. , a species described from western North America on conifers, but the latter forms larger (10–30 mm diam), dark grey pileus without brown tones, and much smaller and less projecting hymenial cystidia (only 19–42 μm long) (Smith 1947, Maas Geesteranus 1988b).

Pairwise comparisons of aligned, overlapping ITS sequences of the São Tomé specimen of M. galopus (BAP 593) showed 99% similarity to four trustworthy sequences of European M. galopus , forming a well-supported clade (99% BS, 1.0 PP) in the ITS phylogeny ( Fig. 2).

Figures

FIGURE 12. Basidiomata of Mycena galopus (BAP 593). Scale bar = 10 mm.

FIGURE 13. Mycena galopus (BAP 593). a. Basidiospores. b. Basidia. c. Cheilocystidia. d. Pileipellis hyphae. e. Stipitipellis hyphae. Scale bar = 10 μm.