Mycena breviseta Höhnel (1909: 283)

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 : 21-22

7. Mycena breviseta Höhnel (1909: 283) ( Fig. 14 )

Description:— Pileus 1.5–2 mm diam, convex, margin becoming eroded or fimbricate in age, striate; surface covered with long, hyaline setae up to 0.4 mm long, greyish white, developing brown tones in age. Lamellae ascending to adnate, subdistant with 1 series of lamellulae, white. Stipe 10–17 × <0.5 mm, central, terete, cylindrical, hollow, arising from a small (<1 mm diam), yellowish brown basal disc; surface covered with short, minute hairs, greyish white, developing yellowish brown tones with moisture loss. Odour indistinct; taste not recorded. Bioluminescence undetected.

Basidiospores 8.0–9.6 × 4.0–4.8 μm [x m = 8.68 ± 0.54 × 4.42 ± 0.4 μm, Q = 1.67–2.20, Q m = 1.97 ± 0.09, n = 20, s = 1], ellipsoid, smooth, hyaline, weakly amyloid, thin-walled. Basidia 12–16.8 × 7.2–9.6 μm, clavate, hyaline, inamyloid, thin-walled, 4-spored, rarely 2-spored, sterigmata up to 4.8 μm long. Basidioles clavate. Cheilocystidia absent. Pleurocystidia absent. Pileipellis a cutis with differentiated terminal cells, marginal cystidia and pileosetae; hyphae 1.6–5.6 μm diam, repent, cylindrical, smooth, hyaline, inamyloid, thin-walled. Terminal cells numerous; 16– 31 × 10.4–18.5 μm, clavate to broadly clavate, densely spinulose, hyaline, inamyloid, thin-walled; spinulae 0.8–2.4 × 0.8 μm. Marginal cystidia 15.2–34 × 8.0–18 μm, broadly clavate to clavate, densely spinulose, hyaline, inamyloid, thin-walled; spinulae 0.8–1.6 × 0.5–0.8 μm. Pileosetae scattered; 165–365 × 8–11.2 μm, narrowly cylindrical to acicular, hyaline, inamyloid, thick-walled (up to 4.0 μm). Hypodermium composed of inflated cells up to 22 μm diam, occasionally globose to ovoid, smooth, hyaline, inamyloid, thin-walled. Hymenophoral trama regular to subregular; hyphae 1.6–4.8 μm diam, hyaline, dextrinoid, non-gelatinous, thin-walled. Stipitipellis a cutis with caulocystidia; cortical hyphae 2.4–5.6 μm diam, parallel, cylindrical, hyaline, dextrinoid, thin-walled; medullary hyphae 16–22 μm diam, smooth, dextrinoid, thin-walled. Caulocystidia abundant; 30–111 × 4.8–15 μm, narrowly cylindrical to aculeate, hyaline, inamyloid, thin-walled. Clamp connections present in all tissues except stipe tissues.

Habitat and known distribution:—Gregarious on sticks in secondary upland forest. Africa ( Príncipe); Indonesia (Java).

Material examined:—AFRICA. Príncipe, Roça Pico Papagaio, N01˚37.182’, E07˚23.474’, 20 April 2008, D.E. Desjardin and B.A. Perry, BAP 633 (SFSU).

Notes:— Mycena breviseta was described from Java. The present material forms tiny basidiomata with greyish white, striate pileus with scattered hyaline setae, subdistant lamellae, a filiform, hispidulose, greyish white stipe, weakly amyloid basidiospores with mean 8.7 × 4.4 μm, no cheilocystidia or pleurocystidia, a cutis-type pileipellis with clavate to broadly clavate, densely spinulose terminal cells and marginal cystidia, hyaline pileosetae up to 365 μm long, aculeate caulocystidia, and growth on woody sticks. In combination, these features indicate placement in sect. Longisetae A.H. Sm. ex Maas Geest.

Desjardin and Horak (2002) studied the holotype and reported that no intact basidiomata were present, and provided a translation of the original description. The material from Príncipe matches nicely with the limited data provided by von Höhnel (see Desjardin & Horak 2002). Mycena longiseta is similar, but forms much longer pileosetae (up to 1000 μm), smaller basidiospores (mean 7.3 × 3.7 μm) and marginal cystidia with smooth apices (Desjardin et al. 2002, Desjardin & Horak 2002).

Pairwise comparisons of aligned, overlapping ITS sequences of M. breviseta (BAP 633) with the top ten BLAST results indicate 89.5–91.9% similarity to four sequences determined as Mycena sp. from Norway (KU861567, KU861566, KU861565) and Japan (AB512340). ITS sequences from other members of sect. Longisetae are unavailable for comparison. Mycena breviseta is on a rather long branch sister to M. stylobates in the ITS phylogeny ( Fig. 2) with 82% BS and 1.0 PP support.

Figures

FIGURE 14. Mycena breviseta (BAP 633). a. Basidiospores. b. Basidia. c. Pileipellis hyphae. d. Pileus marginal cystidia. e. Pileosetae. f. Caulocystidia. Scale bar = 10 μm.