Marasmiellomycena tomentosa Q.Na & Y.P.Ge, 2024

Na, Qin, Zeng, Hui, Hu, Yaping, Ding, Hui, Ke, Binrong, Zeng, Zhiheng, Liu, Changjing, Cheng, Xianhao & Ge, Yupeng, 2024, Morphological and phylogenetic analyses reveal five new species of Porotheleaceae (Agaricales, Basidiomycota) from China, MycoKeys 105, pp. 49-95 : 49

Marasmiellomycena tomentosa Q.Na & Y.P.Ge sp. nov.

Figs 11 , 12 , 13 , 14

Diagnosis.

Pileus and stipe distinctly tomentose. Pileus dark brown, subsquamulose. Basidiospores narrowly ellipsoid, slightly amyloid. Hymenial cystidia absent. Pileipellis and stipitipellis sarcodimitic, hyphae thick-walled with yellowish-brown pigments. Pileocystidia and caulocystidia thick-walled with yellow contents. Differs from M. pseudoomphaliiformis by possessing a distinctly tomentose, dark-brown subsquamulose pileus, narrowly ellipsoid basidiospores and absence of cheilocystidia.

Holotype.

China. Zhejiang Province: Tianmu Mountain, Hangzhou City, 30 Jul 2021, Qin Na, Zewei Liu, Yulan Sun and Yupeng Ge, FFAAS1036 (collection number MY0421).

Etymology.

Name refers to the tomentose to subsquamulose pileus.

Description.

Pileus 0.5-18.5 mm in diameter, at first convex or campanulate, soon expanding to plano-convex, always depressed to umbilicate at the centre, surface dry, densely covered with minute white (LIII) pubescence, tomentose all over, subsquamulose, ground colour Verona Brown (XXIX13′′k) to Warm Sepia (XXIX13′′m), Mustard Yellow (XVI19′b), Old Gold (XVI19′i) to Buffy Citrine (XVI19′k), Saccardo’s Olive (XVI19′m) at the centre, fading to Wax Yellow (XLVI21′′′′f) when old, margin slightly sulcate, uplifted or recurved in age. Context thin, Primrose Yellow (XXX23′′d). Lamellae decurrent to subdecurrent, Wax Yellow (XLVI21′′′′f), Mustard Yellow (XVI19′b), with 1-2 tiers of lamellulae, edges concolorous with the face, slightly fimbriate edge. Stipe 7.5-21.0 × 1.0-1.6 mm, central, terete, curved, equal or slightly broadened at the base, hollow or stuffed, dry, Mustard Yellow (XVI19′b) in the upper part, Saccardo’s Olive (XVI19′m), Benzo Brown (XLVI13′′′′i), Fuscous (XLVI13′′′′m), Deep Greyish-Olive (XLVI21′′′′b) towards the base, densely and minutely silky-fibrillose and white (LIII) pruinose-floccose to tomentose throughout, base covered with white mycelium. Odour indistinct to fungoid, taste mild.

Basidiospores (80/4/3) (6.8) 7.2-7.6-8.2 (8.4) × (3.7) 3.9-4.1-4.5 (4.6) μm [Q = 1.75-1.98, Q = 1.83 ± 0.052] [holotype (40/2/1) (6.8) 7.2-7.7-8.4 × 3.9-4.2-4.6 μm, Q = 1.75-1.98, Q = 1.82 ± 0.050], narrowly ellipsoid, hyaline in 5% KOH, smooth, thin-walled, multiguttulate, slightly amyloid. Basidia 20-35 × 5-8 μm, 2- or 4-spored, clavate, sterigmata 2.2-4.8 × 0.6-1.6 μm. Hymenial cystidia absent. Lamellar trama subregular; hyphae 3-10 μm wide, with 0.5-1.0 µm thick-walled, light yellow, dextrinoid. Pileipellis hyphae 3-8 μm wide, sarcodimitic, cutis, smooth, 0.4-1.0 μm thick-walled, with intracellular yellowish-brown pigment; pileocystidia 38-223 × 5-12 μm, in clusters, narrowly subulate or narrowly lageniform to fusiform with very long and tapering neck, distinctly 0.6-1.5 μm thick-walled, yellow, smooth. Stipitipellis made up of cylindrical, 4-9 µm wide hyphae, sarcodimitic, smooth, 0.5-1.0 μm thick-walled, with intracellular brownish-orange pigment; caulocystidia 45-327 × 5-9 μm, similar to the pileocystidia, but usually longer, 0.5-1.3 μm thick-walled, smooth, with intracellular yellowish pigment. Clamps present in all tissues.

Habit and habitat.

Solitary or scattered on rotten branches, twigs and wood debris in Acer , Armeniaca , Cercidiphyllum , Emmenopterys and Picea mixed forests.

Known distribution.

Zhejiang Province, China.

Additional material examined.

China. Zhejiang Province: Tianmu Mountain, Hangzhou City , 30 Jul 2021, Qin Na, Zewei Liu, Yulan Sun and Yupeng Ge, FFAAS1037 (collection number MY0422) ; Zhejiang Province: Tianmu Mountain, Hangzhou City , 1 Aug 2021, Qin Na, Zewei Liu, Yulan Sun and Yupeng Ge, FFAAS1038 (collection number MY0443) .

Notes.

Marasmiellomycena tomentosa is a rare thermophilous species reported from south-eastern areas of China from July to August on rotten branches, twigs and woody debris of deciduous and coniferous trees ( Acer , Armeniaca , Cercidiphyllum , Emmenopterys and Picea ). The most distinctive characteristics of this species are a tomentose, brown subsquamulose pileus, a tomentose stipe, narrowly ellipsoid and slightly amyloid basidiospores, the absence of hymenial cystidia and thick-walled pileipellis, stipitipellis, pileocystidia and caulocystidia with yellow or brownish-orange contents. Species morphologically most closely allied to Marasmiellomycena tomentosa include M. omphaliiforme , M. pseudoomphaliiformis and M. albodescendens . Marasmiellomycena pseudoomphaliiformis resembles M. tomentosa by the presence of a pale beige to brown pileus with finely tomentose to pubescent pileus, but differs in having white to cream-white or beige lamellae rather than yellow, ellipsoid to ellipsoid-fusiform basidiospores [(6.5-)7.0-9.0(-9.5) × 4.0-5.5 µm] and clavate, fusiform to lageniform cheilocystidia ( Senanayake et al. 2023). Marasmiellomycena omphaliiforme is considered to be a closely-related taxon with evident affinities to M. tomentosa -not only regarding its phylogenetic placement, but also in terms of morphological features ( Kühner and Romagnesi 1954; Antonín and Noordeloos 1993, 1997; Consiglio et al. 2022; Senanayake et al. 2023). The two species resemble one another in having a similarly-coloured pileus and stipe, similarly-shaped basidiospores, pileocystidia and caulocystidia and a yellowish-pigmented pileipellis and stipitipellis; however, the minutely pubescent, granulose to subsquamulose pileus, as well as the relative abundance of cheilocystidia, appear to be variable characters in M. omphaliiforme in contrast to the new species ( Kühner and Romagnesi 1954; Antonín and Noordeloos 1993, 1997; Consiglio et al. 2022). According to the description of Consiglio et al. (2022), Marasmiellomycena albodescendens from New Zealand has a pure-white pileus, a thin-walled pileipellis and larger basidiospores (9.6 ± 0.7 µm × 5.2 ± 0.4 µm).

Figures

Figure 11. Basidiomata of Marasmiellomycena tomentosa A-D collection FFAAS 1036, holotype E, F collection FFAAS 1037 G, H collection FFAAS 1038. Scale bars: 10 mm (A-H).

Figure 12. Morphological features of Marasmiellomycena tomentosa (FFAAS 1036, holotype) A basidiomata B basidiospores C basidia D pileipellis and pileocystidia. Scale bars: 10 mm (A); 10 μm (B-D).

Figure 13. Morphological features of Marasmiellomycena tomentosa (FFAAS 1036, holotype) A stipitipellis and caulocystidia. Scale bars: 10 μm (A).

Figure 14. Microscopic features of Marasmiellomycena tomentosa (FFAAS 1036, holotype) A-E basidiospores F basidia G - J lamellae margin. Scale bars: 5 μm (A-E); 10 μm (F-J). Structures were stained in 5 % KOH aqueous solution before photographing.