Taxonomic studies of bluish Mycena (Mycenaceae, Agaricales) with two new species from northern China Author Na, Qin https://orcid.org/0000-0001-8406-6389 Shandong Key Laboratory of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai 264025, China Author Liu, Zewei https://orcid.org/0000-0002-2700-0831 Shandong Key Laboratory of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai 264025, China Author Zeng, Hui https://orcid.org/0000-0003-2025-844X Institute of Edible Mushroom, Fujian Academy of Agricultural Sciences, Fuzhou 350011, China & National and Local Joint Engineering Research Center for Breeding and Cultivation of Featured Edible Mushroom, Fuzhou 350011, China Author Ke, Binrong Institute of Edible Mushroom, Fujian Academy of Agricultural Sciences, Fuzhou 350011, China & National and Local Joint Engineering Research Center for Breeding and Cultivation of Featured Edible Mushroom, Fuzhou 350011, China Author Song, Zhizhong Shandong Key Laboratory of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai 264025, China Author Cheng, Xianhao Shandong Key Laboratory of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai 264025, China Author Ge, Yupeng https://orcid.org/0000-0001-5754-201X Shandong Key Laboratory of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai 264025, China gaiyupeng@126.com text MycoKeys 2022 2022-06-17 90 119 145 http://dx.doi.org/10.3897/mycokeys.90.78880 journal article http://dx.doi.org/10.3897/mycokeys.90.78880 1314-4049-90-119 7EFCA49326145D6BB656E2D26B6820F0 Mycena caeruleomarginata Q. Na & Y.P. Ge sp. nov. Figs 7 , 8 , 9 Diagnosis. This species is characterised by dark brown pileus with a blue margin and the stipe densely pruinose, entirely covered with puberulous hairs and stipe basal disc and acanathocysts of pileipellis absent. Mycena subcaerulea differs from M. caeruleogrisea in having a pileus that is distinctly greyish-brown with a blue centre and margin, turning yellow with age, a stipe tinged greenish-blue and globose to subglobose basidiospores. Holotype. China. Jilin Province: Chixi Protection Station, Erdaobaihe Town, Antu County, Yanbian Korean Autonomous Prefecture, 42°46'35"N , 128°15'04"E , 3 July 2021, Qin Na, Yupeng Ge, Binrong Ke and Chi Yang, FFAAS 0357 (collection number MY0337). Etymology. Refers to the pileus, which is blue at the margin. Description. Pileus 3.5-13 mm in diameter, parabolic, obtusely conical when young, hemispherical, campanulate with age, with an umbo at the centre, shallowly sulcate, translucently striate, smooth, slightly gelatinous, the margin infrequently out of flatness, dark brown (6F5-6F7), disc brown (6E6-6E7), becoming greyish-blue (23B5) to blue (23B7) towards the margin (Fig. 7c, d, i ), margin grey (23B1) (Fig. 7c, d, i ), covered by a separable, viscid pellicle. Context white, fragile, thin. Lamellae 14-25 reaching the stem, adnate to slightly adnexed with a short tooth, white, inconspicuously intervenose, edges concolorous with the face. Stipe 32-46 x 1.0-2.0 mm, equal, base sometimes slightly broadened, fragile, hollow, pruinose, entirely puberulous when young (Fig. 7h ), becoming sparingly so, especially in the middle part, when old (Fig. 7e ), greyish-brown (5E3) to brown (5E4), base with an greyish-blue (23B5) tinge (Fig. 7a, f ), sparsely covered with white fibrils, a basal disc absent. Odour and taste indistinctive. Figure 7. Fresh basidiomata of Mycena caeruleomarginata a-f M. caeruleomarginata ( FFAAS 0357 , holotype) g-j M. caeruleomarginata ( FFAAS 0358 ) a, f stipe with a bluish base c, d, i pileus with blue margin e, h densely white, pruinose to pubescent stipe. Scale bars: 10 mm ( a, b, e, f, g, h ); 5 mm ( c, d ); 2 mm ( i, j ). Photographs by Qin Na ( a-f ) and Yupeng Ge ( g-j ). Basidiospores [60/3/2] (6.2) 6.4- 7.1 -7.7 (7.9) x (4.4) 4.7- 5.2 -5.8 (6.0) μm [ Q = 1.23-1.54, Q = 1.36 +/- 0.071] [holotype [40/2/1] (6.4) 6.6- 7.2 -7.7 (7.8) x (4.7) 4.9- 5.2 -5.3 (5.7) μm , Q = 1.26-1.53, Q = 1.39 +/- 0.070], broadly ellipsoid to ellipsoid, hyaline in 5% KOH, guttulate, smooth, thin-walled, amyloid. Basidia 26-35 x 6-12 μm , 4- or 2-spored, clavate. Cheilocystidia 32-48 x 4-6 μm , abundant, clustered, cylindrical or elongated clavate, apically broadly rounded, thin-walled, hyaline, forming a sterile lamellae edge. Pleurocystidia absent. Pileipellis an ixocutis with 2-4 μm wide hyphae, simple, cylindrical excrescences, 2-6 x 1-2 μm , embedded in gelatinous matter; acanathocysts absent. Hypodermium undifferentiated. Hyphae of the stipitipellis 3-6 μm in diameter, smooth, hyaline; caulocystidia smooth, transparent, of two shapes: (1) fusiform or cylindrical, 19-40 x 4-8 μm ; (2) extremely long cylindrical, sometimes with a narrow apex, 115-178 x 5-9 μm . All tissues dextrinoid. Clamps present in all tissues. Figure 8. Morphological features of Mycena caeruleomarginata ( FFAAS 0357 , holotype) a basidiomata b basidia c basidiospores d cheilocystidia e stipitipellis and caulocystidia f pileipellis. Scale bars: 10 mm ( a ); 10 μm ( b-f ). Drawings by Qin Na and Yupeng Ge. Habit and habitat. Scattered on rotten wood in Picea , Pinus , Quercus , Robinia and Tilia mixed forests. Figure 9. Microscopic features of Mycena caeruleomarginata ( FFAAS 0357 , holotype) a-d basidiospores e-g cheilocystidia h-j pileipellis j stipitipellis and caulocystidia. Scale bars: 5 μm ( a-d) ; 10 μm ( e-j ). Structures were stained with Congo Red medium before photographing. Known distribution. Jilin Province, China. Additional material examined. Jilin Province : Hancongling , Erdaobaihe Town , Antu County , Yanbian Korean Autonomous Prefecture , 42°46'36"N , 128°15'04"E , 4 July 2021 , Qin Na, Yupeng Ge, Binrong Ke and Chi Yang, FFAAS 0358 (collection number MY0343) . Remarks. The diagnostic features of M. caeruleomarginata can be used to distinguish this new taxon from the closely-related bluish species M. subcaerulea , M. cyanorhiza , M. amicta and M. interrupta (Table 2 ). Mycena subcaerulea , the species most similar to M. caeruleomarginata , differs in having a pileus that is distinctly greyish-brown with a blue centre and margin, turning yellow with age, a stipe tinged greenish-blue and globose to subglobose basidiospores ( Q = 1.01-1.14) according to the original description and our observations ( Saccardo 1887 ; Smith 1947 ) (Figs 5 , 6 ; Table 2 ). Similar to M. caeruleomarginata , M. cyanorhiza has an entirely puberulous, pruinose stipe with a sky blue base and possesses a gelatinous pileus; however, the pileus of M. cyanorhiza is pale brown, grey to almost white, without a bluish tinge and this species has elongated ellipsoid basidiospores ( Q > 1.6) and lacks smooth cheilocystidia and caulocystidia ( Aronsen and Laessoe 2016 ; Perry et al. 2020 ). In addition, M. amicta resembles M. caeruleomarginata in its bluish pileus, pruinose stipe and pileipellis embedded in a layer of gelatinous matter, but the former differs in having a pale grey-brown pileus that is sometimes ochraceous yellow and greenish when young and bluish when old, a raphanoid odour and elongated ellipsoid basidiospores (7.5-10.7 x 4.5-6.0 µm ) ( Robich 2003 ; Aronsen and Laessoe 2016 ). The Southern Hemisphere species M. interrupta is well characterised by its blue pileus at maturity, a translucent stipe with a basal disc and cheilocystidia with excrescences ( Grgurinovic 2003 ). Furthermore, two new species with bluish basidiomata reported from East Asia, M. lazulina and M. indigotica , can be easily distinguished from the new species in their whitish pileus or tubes similar to Boletus ; M. lazulina having cheilocystidia with numerous excrescences and M. indigotica possesses globose basidiospores ( Terashima et al. 2016 ; Wei and Kirschner 2019 ). Mycena caeruleogrisea and M. caeruleomarginata share the same bluish pileus and stipe base, smooth and cylindrical cheilocystidia and pileipellis embedded in a layer of gelatinous matter. Mycena caeruleomarginata can be readily distinguished, however, based on the dark brown colour of the pileus with a blue margin, yellowish-brown to light brown stipe, broadly ellipsoid to ellipsoid spores and caulocystidia of two shapes.