Marasmius cf. ochroleucus Desjardin & E. Horak (1997: 35)

Kiyashko, Anna A., Malysheva, Ekaterina F., Antonín, Vladimír, Svetasheva, Tatiana Yu. & Bulakh, Eugenia M., 2014, Fungi of the Russian Far East 2. New species and new records of Marasmius and Cryptomarasmius (Basidiomycota), Phytotaxa 186 (1), pp. 1-28 : 13-14

Marasmius cf. ochroleucus Desjardin & E. Horak (1997: 35) ( Fig. 2E , Fig. 5)

Pileus 6–15 mm in diam., at first hemispherical, then rounded convex, smooth or slightly uneven, hygrophanous, margin slightly translucently striate when moist, slightly pruinose, whitish or with yellowish tint especially on the edge (5A2). Lamellae adnexed, crowded, (appr. 28 reaching the stem), narrow, thin, whitish, with concolorous edge. Stipe 30–35 × 1.5–2 mm, cylindrical, not or slightly broadened towards base, hollow, hispidulous, whitish at the top, gradually darkening to dark reddish brown (8F4–5) downwards, basal mycelium scarce, whitish. Odour strongly aromatic, taste not defined.

FIGURE. Microscopic features of Marasmius cf. ochroleucus (LE 295978). A. Spores. B. Basidium. C. Cheilocystidia. D. Pileipellis cells. E. Caulocystidia.―Scale bar = 10 μm.

Basidiospores single in preparation, (7.7)8.1–10.8 × (3.5)4.3–4.9 µm, χ m = 9.5±1.9 × 4.6±0.4 µm, Q = 1.9–2.2, Q m = 2.05±0.2, ellipsoid. Basidia 4-spored, 27–32 × 7–9 µm, clavate. Cheilocystidia in the form of Siccus - type broom cells, main body 15.5–20.0 × 6.1–8.7 µm, clavate, subcylindrical, sometimes tortuous or irregular in outline, more or less thin-walled, with cylindrical thin-walled, obtuse, tortuous, rarely branched projections 7.2–8.5(15.0) µm long, inamyloid. Pleurocystidia absent. Pileipellis a hymeniderm composed of Siccus - type broom cells, main body 15.0– 25.0 × 6.0–10.2 µm, clavate, subcylindrical, more or less thin-walled at the base, thick-walled at apex, projections predominantly 5.2–9.0 µm, rarely up to 15.0 µm long, cylindrical, seldom branched, obtuse, tortuous, thick-walled; all thick-walled parts yellow or brownish in KOH. Caulocystidia numerous, 10.0–32.6 × 6.7–7.8 µm, cylindrical, irregular in outline, obtuse, thin- or slightly thick-walled, hyaline, inamyloid. Clamp connections present in all tissues.

Habitat and distribution: In the Russian Federation it was recorded at one locality, in a small group on litter in a mixed forest. Also known from New Caledonia and Northern Thailand, scattered to gregarious on dicotyledonous leaves ( Wannathes et al. 2009b).

Specimens examined: RUSSIAN FEDERATION. Primorsky Territory: KPNR, watershed of Ananjevka and Gryaznaya rivers, mixed forest ( Quercus mongolica , Carpinus cordata , Abies holophylla ) with deciduous dominants, 43º24′19″ N, 131º32′43″ E, 28 Aug. 2011, T. Svetasheva (LE 95978!), GenBank KF912952 for ITS, KF896249 for nrLSU.

Observations: Morphological features of our specimen correspond in general aspects to the description of M. ochroleucus given by N. Wannathes and co-authors ( Wannathes et al. 2009b). However, it was found that the basidiospores of the Russian specimens are slightly wider (Q m = 2.05 vs. Q m = 2.5), and cheilocystidia are on average also wider (6.0–10.2 µm vs. 4.0–6.0 µm wide) and mostly clavate. The genetic distance between the Russian and Tai ITS sequences is 3.9%. This value slightly exceeds the average level of intraspecific ITS variability in Basidiomycota (3.33%) ( Nilsson et al. 2008). However no studies concerning the intraspecific ITS variability of Marasmius species have been carried out yet. Until further material of this taxon is collected in the studied territory, sequenced and compared with other known specimens, we preliminarily identify our specimen as M. cf. ochroleucus .

Figures

FIGURE 2. Mature basidiocarps. A. Marasmius macrocystidiosus sp. nov. (LE 295996). B–C. Marasmius insolitus sp. nov. (LE 289497). D. Marasmius cohaerens var. mandshuricus var. nov. (LE 295987). E. Marasmius cf. ochroleucus (LE 295978). F. Cryptomarasmius aucubae (LE 289499). G. Marasmius occultatiformis (LE 295976). Scale bar = 1 cm.