Mycena hygrophoroides T.Bau & Q.Na

Na, Qin & Bau, Tolgor, 2019, Recognition of Mycenasect. Amparoina sect. nov. (Mycenaceae, Agaricales), including four new species and revision of the limits of sect. Sacchariferae, MycoKeys 52, pp. 103-124 : 103

Mycena hygrophoroides T.Bau & Q.Na sp. nov. Figs 2h, 5

Diagnosis.

Pileus concave with slight pruinose. Lamellae distant. Stipe with dense white fibrils and swollen base. Acanthocysts forming two types. Caulocystidia long-elliptic with conical excrescences, up to 120 μm long.

Holotype.

CHINA. Guangdong Province, Shaoguan City, Chebaling National Nature Reserve, 8 May 2017, Qin Na, HMJAU 43417.

Etymology.

Name refers to its sparse lamellae.

Description.

Pileus 1.5-2.5 mm in diam., campanulate to hemispherical, applanate or slightly concave at centre, white with greyish shade (6B1), shallowly sulcate, translucent-striate, slightly pruinose, pubescent. Context white, thin and very fragile. Lamellae distant, sparse, white, concolorous with the sides. Stipe 4.5-8.2 × 0.5-0.8 mm, cylindrical, hollow, fragile, pure white (5A1) with a greyish (5B1) base, covered with dense white fibrils, base swollen and not forming basal disc, hirsute. Odour and taste indistinctive.

Basidiospores (6.9-)7.2-8.9(-9.3) × (5.3-)6.4-6.7(-7.1) μm, Q=1.2-1.5, Qav=1.31, broadly-ellipsoid, hyaline in water and 5% KOH, amyloid, smooth. Basidia 15-21 × 7-9 μm, 4- or 2-spored, clavate, hyaline. Cheilocystidia 23-37 × 19-28 μm, subglobose, sphaero-pedunculate to utriform with numerous sharp spines, thin-walled and hyaline, inamyloid. Pleurocystidia absent. Pileipellis hyphae 3-9 μm wide, dextrinoid; cherocytes absent; a cutis overlaid by elements of universal veil, not in chains; acanthocysts forming two types, pyriform to vesicular, 13-29 × 11-24 μm, clavate to ovoid or obovoid, 29-42 × 14-20 μm, inamyloid. Hyphae of the stipitipellis 3-7 μm wide, smooth, dextrinoid; caulocystidia abundant, clavate, long-elliptic, 32-122 × 8-11 μm, with numbers of conical spines, inamyloid. Clamps present in all tissues.

Habit and habitat.

Scattered on rotten wood of coniferous trees, ex. Cunninghamia .

Other specimens examined.

Guangdong Province, Shaoguan City, Liangjiang Town, Shangxie Village, 7 May 2017, Qin Na, HMJAU 43421.

Remarks.

Mycena hygrophoroides could be considered to be a member of Hemimycena Singer owing to the tiny basidiomata and sparse lamellae, but the absence of a basal disc, amyloid spores and spinulose cheilocystidia, acanthocysts and caulocystidia are diagnostic characters for M. hygrophoroides , which should be placed in Mycena sect. Amparoina stirps Alphitophora . Mycena acanthophila J.C.Zamora& Català, of which the holotype was collected from Spain growing on dead branches of Leguminosae , most resembles M. hygrophoroides , but differs in having a yellow pileus, smaller cheilocystidia (13.5-22 × 8.5-12 μm) and diverse caulocystidia (Zamora and Català 2012). Mycena depilata , a species of stirps Alphitophora , shows some morphological similarities to M. hygrophoroides in possessing white and tiny basidiomata, distant lamellae (L = 7-9) and globose-pedicellate acanthocysts with hyaline contents. However, M. depilata differs in producing ellipsoid spores (Q = 1.64 ± 0.11), broadly clavate cheilocystidia and shorter caulocystidia (16-50 × 5-16 μm; Singer 1989). Mycena hemitrichialis is difficult to distinguish from M. hygrophoroides , but M. hemitrichialis has free to subfree lamellae, longer caulocystidia (100-300 × 5-15 μm) and ellipsoid spores ( Singer 1989). In comparison with M. hygrophoroides , M. alphitophora and M. distincta have larger basidiomata and longer caulocystidia of more than 400 μm and 300 μm, respectively ( Desjardin 1995; Aravindakshan and Manimohan 2015). Their noticeably pigmented pileus enables discrimination of M. brunneospinosa , M. incarnativelum and M. roseotincta from M. hygrophoroides ( Desjardin 1995; Aravindakshan and Manimohan 2015). The significantly larger basidiomata and globose spores can be used to distinguish M. corynephora , M. globispora and M. yalensis from M. hygrophoroides .