Atheniella flavida Q. Na & Y.P. Ge, 2021

Ge, Yupeng, Liu, Zewei, Zeng, Hui, Cheng, Xianhao & Na, Qin, 2021, Updated description of Atheniella (Mycenaceae, Agaricales), including three new species with brightly coloured pilei from Yunnan Province, southwest China, MycoKeys 81, pp. 139-164 : 139

Atheniella flavida Q. Na & Y.P. Ge sp. nov.

Figs 2g-i , 3 , 4.

Diagnosis.

Pileus colour changing from orange-yellow to yellow, slightly concave at centre with age, pruninose. Lamellae narrowly adnate. Stipe densely pruinose. Basidiospores globose to subglobose, inamyloid. Cheilocystidia and pleurocystidia fusiform, thin-walled. Pileipellis with mass of excrescences. Caulocystidia cylindrical or lageniform. All tissues non-reactive in iodine. Clamps absent.

Holotype.

China. Yunnan Province, Yuxi City, Xinping County, Mopanshan National Forest Park, 25 Jul 2020, Qin Na, Yupeng Ge and Zewei Liu, FFAAS0350 (Collection No. MY0182).

Etymology.

Refers to the yellow basidiomata.

Description.

Pileus 2.6-4.8 mm in diam., conic when young, becoming almost hemispherical and slightly concave at centre with age, orange-yellow (4A8) when young, fading to cream-yellow (3A4-3A6) at maturity, margin light yellow (3A3), sulcate, translucent-striate, delicately pubescent, pruninose, glabrescent with age, margin waved. Context very thin and fragile, pure white. Lamellae narrowly adnate, ascending, cream-white (3A2) to light yellow (3A3), faces concolorous with the sides, decurrent with a short tooth. Stipe slender, 5.5-12 × 0.5-0.8 mm, cylindrical, hollow, fragile, bright yellow (4A6), densely pruinose on the entire surface, almost smooth when old, base with sparse white fibrils. Odour and taste inconspicuous.

Basidiospores [60/3/2] (6.5) 6.7- 7.2 -7.8 (8.3) × (5.7) 5.9- 6.5 -7.1 (7.8) μm [Q = 1.03-1.22, Q = 1.11 ± 0.043] [holotype [40/2/1] (6.6) 6.7- 7.2 -7.6 (7.9) × (5.8) 5.9- 6.4 -6.9 (7.4) μm, Q = 1.04-1.20, Q = 1.10 ± 0.041], globose to subglobose, hyaline, guttulate, thin-walled, inamyloid. Basidia 20-29 × 5-8 μm, hyaline, clavate, 2-spored. Cheilocystidia abundant, 36-51 × 8-11 μm, fusiform, long-stalked, hyaline, thin-walled. Pleurocystidia similar to cheilocystidia, 28-43 × 6-10 μm. Pileipellis hyphae 2-6 μm wide, cutis; covered with mass of excrescences, 3.3-8.2 × 1.2-3.4 μm, hyaline. Hyphae of the stipitipellis 2-8 μm wide, hyaline, smooth; caulocystidia cylindrical or lageniform, 14-37 × 5-11 μm, hyaline, thin-walled. All tissues non-reactive in iodine. Clamps not seen in all tissues.

Habit and habitat.

Solitary to scattered on rotten wood in evergreen broad-leaf forest, Cephalotaxus , Cunninghamia , Keteleeria , Podocarpus , Pseudotaxus , Pseudotsuga , Sequoia , Taxus , Torreya and Tsuga .

Other specimens examined.

China. Yunnan Province, Yi Autonomous Prefecture, Chuxiong City, Zixishan , 27 Jul 2020, Qin Na, Yupeng Ge and Zewei Liu, FFAAS0355 (Collection No. MY 0234) .

Remarks.

Atheniella flavida is considered to be a distinct species in Atheniella on account of the pileus colour changing from orange-yellow to yellow, globose to subglobose basidiospores and caulocystidia comparatively small ( Maas Geesteranus 1980, 1990, 1992a, 1992b; Perry 2002; Robich 2003; Aronsen and Læssøe 2016). Four species with a yellow or orange pileus are recorded: A. aurantiidisca , A. delectabilis (Peck) Lüderitz & H. Lehmann, A. flavoalba and A. leptophylla (Peck) Gminder & Böhningare ( Smith 1935b; Maas Geesteranus 1980; Robich 2003; Aronsen and Læssøe 2016). Atheniella flavoalba , which is the most widely distributed species in the Northern Hemisphere, often seen in northeast China (Fig. 2a-c ), shows the most morphological similarities to A. flavida ; however, the former differs in forming cylindrical spores (6.5-9 × 3-4.5 μm) and the caulocystidia are fusiform and clavate to globose ( Perry 2002; Robich 2003; Aronsen and Læssøe 2016; Na 2019). In contrast to A. flavida , A. aurantiidisca , which had been found in Yunnan Province and Tibet Autonomous Region of China (Fig. 2d-f ) and A. leptophylla are easily mistaken for the new species ( Robich 2003; Aronsen and Læssøe 2016; Na 2019). However, the pileus of A. aurantiidisca and A. leptophylla is constantly distinctly orange and caulocystidia of the two species are larger (up to 50 μm long) ( Robich 2003; Aronsen and Læssøe 2016). Atheniella delectabilis , which was formerly named Hemimycena delectabilis (Peck) Singer on account of the white to yellowish-white pileus, decurrent lamellae and inamyloid basidiospores, is easily mistaken for A. flavida by the light yellowish pileus and the similar shape and size of cheilocystidia and caulocystidia. However, A. delectabilis is distinguishable from A. flavida by its decurrent lamellae and cylindrical spores (7-9 × 3-4 μm) ( Smith 1935b; Malysheva and Morozova 2009). In addition, A. delectabilis produces cheilocystidia that are partially thick-walled ( Smith 1935b).

Figures

Figure 2. Basidiomata of Atheniella species a-c Atheniella adonis (Bull.) Redhead, Moncalvo, Vilgalys, Desjardin & B. A. Perry d-f Atheniella aurantiidisca (Murrill) Redhead, Moncalvo, Vilgalys, Desjardin & B. A. Perry g-i Atheniella flavida Q. Na & Y. P. Ge j-l Atheniella flavoalba (Fr.) Redhead, Moncalvo, Vilgalys, Desjardin & B. A. Perry m-p Atheniella rutila Q. Na & Y. P. Ge q-s Atheniella taoyao Q. Na & Y. P. Ge. Scale bars: 10 mm (a-f, j-l, n-p), 5 mm (g-i, q-s). Photographs a, b, d-h, j-o, q, r by Qin Na; c, i, p, s by Yupeng Ge.

Figure 3. Microscopic features of Atheniella flavida (FFAAS 0350, holotype) a-c basidiospores d basidia e, f cheilocystidia g, h pleurocystidia i pileipellis j stipitipellis and caulocystidia. Scale bars: 10 μm (a-j).

Figure 4. Morphological features of Atheniella flavida (FFAAS 0350, holotype) a basidiomata b basidia c pleurocystidia d basidiospores e cheilocystidia f stipitipellis and caulocystidia g pileipellis. Scale bars: 10 mm (a); 10 μm (b-g). Drawings by Qin Na and Yupeng Ge.