Pulverulina flavoalba 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

Pulverulina flavoalba Q.Na & Y.P.Ge sp. nov.

Figs 15 , 16 , 17

Diagnosis.

Pileus white to light orange yellow. Basidiospores cylindrical. Hymenial cystidia absent. Lamellar trama, pileipellis and stipitipellis hyphae thin-walled. Differs from Pu. ulmicola in having larger and longer basidiospores and possessing thin-walled lamellar trama, pileipellis and stipitipellis hyphae.

Holotype.

China. Guangxi Zhuang Autonomous Region: Liangfengjiang National Forest Park, Nanning City, 13 Jul 2022, Yupeng Ge and Renxiu Wei, FFAAS1039 (collection number MY0863).

Etymology.

Name refers to the white to light-yellow pileus and stipe.

Description.

Pileus 1.2-5.8 mm in diameter, arched or plano-convex with a slight depression at the centre when young, becoming more depressed with age; translucent striate, floccose or granulose, glabrescent when old, surface dull, dry; white (LIII) when young, aniline yellow (IV19i) or light orange-yellow (III17d) at the centre and in the margin with age, margin decurved. Context white, thin, not fragile. Lamellae decurrent, white, orange citrine (IV19k) tinged when old, with 1-2 tiers of lamellulae, edges even, medium-broad. Stipe 1.6-14.4 × 0.5-1.0 mm, terete or slightly broadened at the base, curved, dry, white, with a pruinose, pubescent or fibrillose surface, sparser with age, hollow, not fragile, white, sometimes aniline yellow (IV19i), light orange-yellow (III17d) in the middle and at the base; base covered with white mycelium. Odour absent, taste mild.

Basidiospores (60/3/2) (6.8) 7.0-7.9-8.8 (9.1) × (3.3) 3.7-4.1-4.4 (4.7) μm [Q = 1.81-2.19, Q = 1.93 ± 0.099] [holotype (40/2/1) (6.8) 7.0-7.8-8.9 (9.1) × (3.3) 3.7-4.1-4.4 (4.7) μm, Q = 1.77-2.19, Q = 1.92 ± 0.084], cylindrical, hyaline in 5% KOH, smooth, thin-walled, guttulate, inamyloid, with a small, but discernible apiculus. Basidia 21-30 × 4-6 μm, 2- or 4-spored, clavate, sterigmata 1.9-5.6 × 0.6-1.6 μm. Hymenial cystidia absent. Lamellar trama subregular to interwoven; hyphae 5-15 µm wide, hyaline, thin-walled. Pileipellis a cutis of cylindrical hyphae 3-7 µm wide, smooth; end cells often protruding, 35-105 × 3-12 μm, cylindrical, subfusiform, apically obtuse, thin-walled, hyaline, smooth. Stipitipellis hyphae 3-8 μm wide, smooth, thin-walled; caulocystidia 19-50 × 4-9 μm, clavate, subfusiform, thin-walled, smooth, transparent. Clamps present in all tissues.

Habit and habitat.

Scattered to gregarious on rotten wood, branches or fruits in mixed forests of Acacia , Ficus , Ilex , Parashorea , Picea and Trachycarpus etc.

Known distribution.

Guangxi Zhuang Autonomous Region, China.

Additional material examined.

China. Guangxi Zhuang Autonomous Region: Liangfengjiang National Forest Park, Nanning City , 13 Jul 2022, Yupeng Ge and Renxiu Wei, FFAAS1040 (collection number MY0865) .

Notes.

Clitocybe ulmicola H.E. Bigelow was established by Bigelow in 1982 and published as a new combination, Pulverulina ulmicola (H.E. Bigelow) Matheny & K.W. Hughes ( Matheny et al. 2020). The description of Pulverulina ulmicola modified from Bigelow (1982) includes observations based on recent American material ( Matheny et al. 2020). As far as we know, only Pulverulina ulmicola has previously been included in the genus and has had morphological features described in detail ( Bigelow 1982; Matheny et al. 2020). In appearance, Pulverulina ulmicola is a small, whitish, marasmioid fungus, with small basidiomata, distant decurrent lamellae, a tough texture, interwoven gill trama, long cylindrical caulocystidia and short, ellipsoid, smooth basidiospores and occurs on the bark of living Ulmus and Quercus trees. Our collections of Pulverulina flavoalba from the Guangxi Zhuang Autonomous Region represent a taxon that is distinct from Pulverulina ulmicola , as compared to the macroscopic and microscopic characters described by Matheny et al. (2020). Pulverulina ulmicola differs from P. flavoalba in having a white or whitish to very pale brown or faintly greyish pileus, broadly ellipsoid to ovoid basidiospores and lamellar trama, pileipellis and stipitipellis hyphae with thickened walls ( Matheny et al. 2020). The Pulverulina genus comprises two additional species besides Pulverulina ulmicola , namely Pulverulina cyathella (J. Favre & Schweers ex Kuyper) Chalange & P.-A. Moreau and Pulverulina praticola (Kuyper, Arnolds & P.-J. Keizer) Chalange & P.-A. Morea. These two species were transferred to Pulverulina by Chalange and Moreau (2023) from their previous classification under Omphalina . Both species can be readily distinguished from Pulverulina flavoalba based on their spore size and morphology. Specifically, the spores of Pulverulina praticola [(6.0-)6.5-8.0(-8.5) × (5.0-)5.5-6.5(-7.0) μm] are noticeably wider than those of Pulverulina flavoalba , resulting in a significantly lower Q value (Q = 1.1-1.3, Qmean = 1.2) compared to Pulverulina flavoalba ( Kuyper et al. 1997). Similarly, Pulverulina cyathella also exhibits wider spores [(5.5-)6.5-7.0 × (5.0-)6.0-6.5 μm] and are (sub)globose in shape, distinguishing them from the cylindrical spores of Pulverulina flavoalba ( Kuyper 1996).

Figures

Figure 15. Basidiomata of Pulverulina flavoalba A-D collection FFAAS 1039, holotype E-H collection FFAAS 1040. Scale bars: 5 mm (A-H).

Figure 16. Morphological features of Pulverulina flavoalba (FFAAS 1039, holotype) A basidiomata B basidia C basidiospores D caulocystidia E pileipellis. Scale bars: 2 mm (A); 10 μm (B, D, E); 5 μm (C).

Figure 17. Microscopic features of Pulverulina flavoalba (FFAAS 1039, holotype) A - E basidiospores F basidia G lamellae margin H lamellar trama I pileipellis J caulocystidia. Scale bars: 5 μm (A-E); 10 μm (F-J). Structures A-F were stained in 5 % KOH aqueous solution and G-J with 1 % Congo Red aqueous solution before photographing.