Mycena rufobrunnea Z.W. Liu, Y.P. Ge & 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 rufobrunnea Z.W. Liu, Y.P. Ge & Q. Na, sp. nov.

Figs 6 , 7 , 8

Diagnosis.

Pileus dark brown at centre, disc gradually turning paler to reddish-brown to greyish-brown, edge white. Lamellae obviously intervenose. Stipe apex to middle greyish-magenta to dull violet, lower part darker to dark purple or dark magenta. Cheilocystidia utriform, sometimes clavate. Pleurocystidia absent. Caulocystidia clavate or fusiform. Pileipellis with fusiform terminal cells.

Holotype.

China. Jilin Province: Dayangcha, Erdaobaihe Town, Antu County, Yanbian Korean Autonomous Prefecture, 42°20'73"N, 127°56'06"E, 16 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0416 (collection number MY0581).

Etymology.

Refers to reddish-brown pileus.

Description.

Pileus 12-34 mm in diam., hemispherical to convex when young, then plano-convex, sometimes an unclear umbo at centre, margin slightly revolute, acute to subacute, at times cracked at mature; dark brown (8F6-8F8) at centre, disc gradually turning paler to reddish-brown (8D4-8D5, 8E6-8E8) to greyish-brown (8D3) and turning to whitish at margin; striate reddish-brown (8D4-8D5, 8E6-8E8), towards the centre up to 1/3-1/2 diam.; surface humidus when wet. Context white, 1.5 mm thick, fragile. Lamellae adnexed to emarginate, 20-23 reaching the stipe, 1-3 tiers of lamellulae, white, irregularly intervenose, edge concolorous, slightly serrulate. Stipe 19-62 × 2-6 mm, central, cylindrical, apex to middle greyish-magenta (14E4-14E5) to dull violet (16E3-16E4), lower part darker to dark purple (14F4-14F5) or dark magenta (13F3), fragile, hollow, base slightly swollen with whitish villose. Odour raphanoid, taste indistinct.

Basidiospores (80/4/3) (7.1)7.6-8.4-9.2(9.6) × (3.8)4.0-4.5-5.0 μm [Q = (1.73)1.77-1.98(2.05), Q = 1.88 ± 0.07] [holotype (40/2/1) (7.9)8.1-8.6-9.2(9.4) × 4.2-4.6-5.0 μm, Q = (1.73)1.77-1.96(1.98), Q = 1.87 ± 0.06], elongated ellipsoid to cylindrical, colourless, smooth, thin-walled, amyloid. Basidia 24-34 × 7-10 μm, 4-spored, clavate, hyaline, sterigmata 2-3 μm in length. Cheilocystidia thin-walled, hyaline, utriform, sometimes clavate, 23-44 × 7-17 μm, abundant. Pleurocystidia absent. Pileipellis a cutis composed of four to five slightly interwoven layers of cylindrical cells, 44-70 × 4-7 μm, smooth, thin-walled; terminal cells cylindrical or fusiform, 34-65 × 4-17 μm, thin-walled, hyaline. Hypodermium formed by fusiform, subcylindrical to subglobose hyphae, 15-50 × 12-37 μm, thin-walled, hyaline. Lamellar trama subregular, dextrinoid. Stipitipellis a cutis composed of hyphae 3-9 μm in diam., smooth, thin-walled; caulocystidia common in the apex, sparse in the middle and base, 23-76 × 6-14 μm, clavate and fusiform, thin-walled, hyaline, smooth. Clamps present in all tissues.

Habitat.

Scattered on the decayed logs of Acer , Larix , Pinus , Populus , Quercus and Ulmus mixed forests.

Known distribution.

Jilin Province, China.

Additional material examined.

China. Jilin Province: Dayangcha, Erdaobaihe Town , Antu County, Yanbian Korean Autonomous Prefecture , 42°20'72"N, 127°56'08"E, 16 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0414 (collection number MY0579); same location, 16 August 2021, Zewei Liu, Yupeng Ge, Qin Na and Shixin Wang, FFAAS0415 (collection number MY0580) .

Notes.

Species of sect. Mycena Calodontes that are macroscopically similar to Mycena rufobrunnea have been recorded in many regions of the world. Most taxa resemble M. rufobrunnea in pileus colour ( Smith 1947; Maas Geesteranus 1992a, 1992b; Grgurinovic 2003; Robich 2003; Chew et al. 2014; Aronsen and Læssøe 2016). Mycena dura Maas Geest. & Hauskn., recorded in Europe, also has a dark brown to greyish-brown pileus, but can be distinguished from M. rufobrunnea in having a white stipe and having pleurocystidia ( Robich 2003; Aronsen and Læssøe 2016). Mycena kuehneriana A.H. Sm., which is recorded from the United States and Canada, is distinguished from M. rufobrunnea in that its pileus is pale avellaneous with rose and lilac, almost white when faded and the spores are obviously smaller (5-6 × 2-3 μm) ( Smith 1947; Maas Geesteranus 1992a, 1992b). Mycena clarkeana Grgur. and M. nullawarrensis Grgur., described from Australia, are similar to M. rufobrunnea in having a reddish-brown pileus, but both species have broader spores and possess pleurocystidia ( Grgurinovic 2003). Mycena cahaya A.L.C. Chew & Desjardin, M. seminau A.L.C. Chew & Desjardin and M. sinar A.L.C. Chew & Desjardin, known from Malaysia, resemble M. rufobrunnea owing to the brown pileus, but differ in having adnate to subdecurrent lamellae, a yellowish-grey or brownish-orange stem, mucronate cheilocystidia and lack caulocystidia ( Chew et al. 2014). Microscopically, utriform or clavate cheilocystidia and absence of pleurocystidia are key characteristics of M. rufobrunnea . Mycena diosma Krieglst. & Schwöbel has similar cheilocystidia and pleurocystidia are absent or rare, but it has a strongly hygrophanous pileus and a remarkable change in colour ( Robich 2003; Aronsen and Læssøe 2016). Mycena pura , M. sirayuktha and M. vinacea Cleland have similar cheilocystidia, but are easily distinguished from M. rufobrunnea by the presence of pleurocystidia ( Perry 2002; Grgurinovic 2003; Robich 2003; Aravindakshan and Manimohan 2015; Aronsen and Læssøe 2016; Na 2019).

Figures

Figure 6. Basidiomata of Mycena rufobrunnea Z. W. Liu, Y. P. Ge & Q. Na a, b FFAAS 0414 c, d FFAAS 0415 e-h FFAAS 0416, holotype. Scale bars: 10 mm (a-h). Photographs a-h by Qin Na.

Figure 7. Microscopic features of Mycena rufobrunnea (FFAAS 0416, holotype) a-d basidiospores e basidia f-l cheilocystidia m lamellar trama n pileipellis and hypodermium o stipitipellis and caulocystidia. Scale bars: 5 μm (a-d); 20 μm (e-o).

Figure 8. Morphological features of Mycena rufobrunnea (FFAAS 0416, holotype) a basidiomata b basidia c cheilocystidia d basidiospores e stipitipellis and caulocystidia f pileipellis and hypodermium. Scale bars: 10 mm (a); 10 μm (b-f). Drawings by Zewei Liu.