Mycena caeruleomarginata Q. Na & Y.P. Ge, 2022

Na, Qin, Liu, Zewei, Zeng, Hui, Ke, Binrong, Song, Zhizhong, Cheng, Xianhao & Ge, Yupeng, 2022, Taxonomic studies of bluish Mycena (Mycenaceae, Agaricales) with two new species from northern China, MycoKeys 90, pp. 119-145 : 119

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 × 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.

Basidiospores [60/3/2] (6.2) 6.4- 7.1 -7.7 (7.9) × (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) × (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 × 6-12 μm, 4- or 2-spored, clavate. Cheilocystidia 32-48 × 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 × 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 × 4-8 μm; (2) extremely long cylindrical, sometimes with a narrow apex, 115-178 × 5-9 μm. All tissues dextrinoid. Clamps present in all tissues.

Habit and habitat.

Scattered on rotten wood in Picea , Pinus , Quercus , Robinia and Tilia mixed forests.

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 Læssøe 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 × 4.5-6.0 µm) ( Robich 2003; Aronsen and Læssøe 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.

Figures

Figure 5. Microscopic features of Mycena subcaerulea a, b basidiospores (TENN-F- 057919) c basidiospores (CUP-A- 002382) d basidiospores (CUP-A- 015138) e-g cheilocystidia (TENN-F- 057919) h, i pileipellis (TENN-F- 057919) j stipitipellis and caulocystidia (TENN-F- 057919). Scale bars: 5 μm (a-d); 10 μm (e-j). Structures were stained with Congo Red medium before photographing.

Figure 6. Morphological features of Mycena subcaerulea a basidiospores b basidia c stipitipellis and caulocystidia d cheilocystidia e pileipellis. Scale bars: 10 μm (a-e). Drawings by Qin Na and Yupeng Ge.

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).

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.

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.