Mycena polycystidiata Z.W. Liu, Y.P. Ge, L. Zou & Q. Na, sp. nov.

Liu, Zewei, Ge, Yupeng, Zeng, Hui, Cheng, Xianhao & Na, Qin, 2022, Four new species of Mycena sect. Calodontes (Agaricales, Mycenaceae) from northeast China, MycoKeys 93, pp. 23-56 : 23

Mycena polycystidiata Z.W. Liu, Y.P. Ge, L. Zou & Q. Na, sp. nov.

Figs 2 , 3 , 4 , 5

Diagnosis.

Pileus greyish-rose, umbo brownish-orange, hygrophanous. Stipe pubescent. Pleurocystidia polymorphic in shape. Stipitipellis a cutis, with numerous projecting hyphae.

Holotype.

China. Heilongjiang Province: Liangshui National Nature Reserve, Yichun City, 47°12'74"N, 128°52'86"E, 20 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0417 (collection number MY0633).

Etymology.

Refers to the variable shape of pleurocystidia.

Description.

Pileus 14-31 mm in diam., campanulate to hemispherical when young, plano-convex with age, with obtuse umbo at centre, margin slightly revolute, at times cracked at mature; umbo brownish-orange (7C3-7C5), disc purplish-grey (13C2, 14B2, 14C2), reddish-grey (12B2, 12C2) to greyish-rose (12B3), near margin reddish-grey (12D2), greyish-ruby (12D3) or purplish-grey (13D3), margin whitish; striate none or indistinct, greyish-ruby (12E3-12E4), towards the centre up to 1/3 diam.; surface dry and rugose, hygrophanous, generally tomentose. Context white, 2 mm thick, fragile. Lamellae emarginate, slightly decurrent when old, 20-28 reaching the stipe, 1-2 tiers of lamellulae, white, irregularly intervenose, edge concolorous, wavy. Stipe 34-73 × 3-7 mm, central, cylindrical, base occasionally compressed with age; apex violet brown (11E3-11E4, 11F4), greyish-ruby (12E4), lower part brownish-grey (11D2, 11E2) to greyish-brown (11D3, 11E3) or purplish-grey (13C2), fragile, hollow; apex to middle densely pubescent, sparser towards base; whitely villose at base. Odour strongly raphanoid, taste indistinct.

Basidiospores (130/5/4) (6.4)6.7-7.4-8.3(8.8) × (3.2)3.5-3.9-4.3(4.6) μm [Q = (1.62)1.72-2.05(2.18), Q = 1.90 ± 0.11] [holotype (70/2/1) (6.7)6.9-7.6-8.5(8.7) × (3.4)3.6-4.0-4.4(4.6) μm, Q = (1.71)1.76-2.05(2.13), Q = 1.90 ± 0.09], elongated ellipsoid to cylindrical, colourless, smooth, thin-walled, amyloid. Basidia 21-31 × 6-8 μm, 4-spored, clavate, hyaline, sterigmata approximately 4 μm in length. Cheilocystidia thin-walled, hyaline, differs in two shapes, mainly utriform, 50-65 × 20-31 μm, some subclavate, 54-78 × 14-19 μm. Pleurocystidia abundant, thin-walled, hyaline, multi-shaped: lanceolate and mostly round to blunt apices, 37-81 × 12-20 μm, lanceolate and acute apices, 51-87 × 14-22 μm, elliptical, 30-86 × 12-31 μm, ovate and acute apices, 49-71 × 15-24 μm, ovate and mostly round to blunt apices, 49-73 × 16-22 μm. Pileipellis a cutis composed of four to five layers cylindrical cells, 51-81 × 4-5 μm, smooth and thin-walled; terminal cells cylindrical or fusiform, 50-69 × 3-22 μm, thin-walled, hyaline. Hypodermium formed by fusiform to subglobose hyphae, 32-69 × 18-54 μm, thin-walled, hyaline. Lamellar trama subregular, dextrinoid. Stipitipellis a cutis composed of cylindrical hyphae 5-8 μm in diam., smooth, thin-walled, with numbers of projecting hyphae 2-6 μm in diam.; caulocystidia 29-74 × 6-19 μm, clavate or fusiform, thin-walled, smooth, hyaline. Clamps present in all tissues.

Habitat.

Scattered on the litter layers in Pinus koraiensis and Larix gmelinii mixed forests.

Known distribution.

Heilongjiang Province, China.

Additional material examined.

China. Heilongjiang Province: Liangshui National Nature Reserve, Yichun City , 47°12'82"N, 128°52'94"E, 20 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0418 (collection number MY0634) ; same location, 21 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0421 (collection number MY0659) ; same location, 21 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0422 (collection number MY0661) .

Notes.

Macroscopically, Mycena luteovariegata Harder & Læssøe and M. pura resemble M. polycystidiata in pileus colour, but the latter possesses more typically utriform cheilocystidia and uncontracted pleuro- and cheilocystidia ( Perry 2002; Robich 2003; Harder et al. 2013; Aronsen and Læssøe 2016; Na 2019). Mycena pearsoniana also has a rose to violaceous pileus, but differs from M. polycystidiata in having inamyloid spores and lacking pleurocystidia ( Aronsen and Læssøe 2016; Na 2019). Compared with M. polycystidiata , M. sirayuktha Aravind. & Manim. has similar cheilocystidia, but has an obviously greyish-brown striate pileus, inamyloid spores and slightly glutinous pileipellis with finger-like excrescences ( Aravindakshan and Manimohan 2015).

The pleurocystidia of M. polycystidiata varied in shape amongst specimens (Fig. 5 ). In all four specimens, most pleurocystidia were lanceolate and with round to blunt apices, but pleurocystidia with lanceolate and acute apices, elliptical and ovate and acute apices were also observed in FFAAS0417 (Holotype) and FFAAS0418, while elongated lageniform-lanceolate or round apices ovate were detected in FFAAS0421 and FFAAS0422. The multi-shaped pleurocystidia may show a morphological continuum that changes between developmental stages. Nevertheless, the multi-shaped pleurocystidia are unquestionably diagnostic for identification of this species.

Figures

Figure 2. Basidiomata of Mycena polycystidiata Z. W. Liu, Y. P. Ge, L. Zou & Q. Na a, b FFAAS 0422 c, d FFAAS 0417, holotype e-g FFAAS 00421 h FFAAS 0418 Scale bars: 10 mm (a-h). Photographs a-e, h by Qin Na f, g by Yupeng Ge.

Figure 3. Microscopic features of Mycena polycystidiata (FFAAS 0417, holotype) a-f basidiospores g basidia h-l cheilocystidia m-r pleurocystidia s pileipellis and hypodermium t lamellar trama u stipitipellis and caulocystidia. Scale bars: 5 μm (a-f); 10 μm (g); 30 μm (h-r); 40 μm (s-u).

Figure 4. Morphological features of Mycena polycystidiata (FFAAS 0417, holotype) a basidiomata b basidia c basidiospores d pleurocystidia e cheilocystidia f stipitipellis and caulocystidia g pileipellis and hypodermium. Scale bars: 10 mm (a); 10 μm (b-g). Drawings by Zewei Liu.

Figure 5. Pleurocystidia of Mycena polycystidiata a FFAAS 0422 b FFAAS 0417, holotype c FFAAS 0418 d FFAAS 0421. Scale bars: 25 μm (a-d).