Parasola eburnea T. Bau & L. Y. Zhu, 2025

Zhu, LiYang & Bau, Tolgor, 2025, Emendation of morphology and infrageneric standards of Parasola (Psathyrellaceae, Agaricales) and its species diversity in China, IMA Fungus 16, pp. e 143796-e 143796 : e143796-

Parasola eburnea T. Bau & L. Y. Zhu sp. nov.

Figs 17 a – f , 18

Diagnosis.

Pileus lacteous, pale gray to gray at margin, sordid yellow to slightly ochreous in center, sulcate-striate almost up to center, ridge of plication fine grained; lamellae free and remote from stipe by pseudocollarium; basidiospores 9.7–10.9 × 10.0–10.4 × 8.4–9.4 μm, rhomboid or mitriform in front view, ellipsoid to narrow ellipsoid in side view, with slightly eccentric or almost central germ pore of 1.8–2.1 μm in diam; sclerocystidia absent.

Etymology.

The specific epithet “ eburnea ” refers to the white with slightly sordid yellow color of the basidiocarp.

Type.

CHINA • Jilin Province, Changchun City, campus of Jilin Agricultural University , 43°80'91"N, 125°40'94"E, 201 m a. s. l., September 15 th 2021, L. Y. Zhu, HMJAU 60347 (Z 21091503, holotype) .

Description.

Pileus 4–8 × 5–10 mm when still closed, 5–13 mm when mature, at first ovoid or ellipsoid, then paraboloid, finally almost flattened, sometime with a depressed disc at center; dry; sordid yellow to slightly ochreous and in center, sometimes with red-brown hue when dry, lacteous, pale gray or gray at margin, slight brown at center at age; sulcate-striate almost up to center, ridge edge fine-grained. Context extremely thin, almost unseen, odor and taste not distinctive. Lamellae medium crowded, free and remote from stipe by pseudocollarium, 1–2 mm in wide, L = 19–28, I = 1, first white to beige, pale gray to purple-gray when expanded, hardly deliquescent with age. Stipe 15–45 × 1–2 mm, cylindrical, hollow, equal or attenuate towards the apex, white to gray brown, somewhat translucent when moist, glabrous, at base somewhat swollen. Spore print not recorded.

Basidiospores [47, 4, 2] (9.0 –) 9.7–10.9 (– 12.1) × (9.0 –) 10.0–10.4 (– 11.4) × (7.8 –) 8.4–9.4 (– 9.9) μm, Q 1 = 1.16–1.40, Q 2 = 1.35–1.83, av. Q 1 = 1.30, av. Q 2 = 1.58; rhomboid or mitriform, with apical papilla and convex base in front view, flattened, ellipsoid to narrow ellipsoid in side view; smooth, yellow-brown to dark brown-gray, with yellow-brown oil droplet; inamyloid; germ pore slightly eccentric or almost central, 1.8–2.1 μm wide. Basidia dimorphic, 17–43 × 8–16 μm, sterigma 3–6 μm, clavate, occasionally constricted in middle part, hyaline, 4 - or 2 - spored, surrounded with 4–6 pseudoparaphyses; subhymenium composed of subglobose, ellipsoid, oblong or cylindrical elements, 8–19 × 6–14 μm. Cheilocystidia 16–52 × 10–22 μm, abundant, subglobose, utriform, ellipsoid, sublageniform or subcylindrical, smooth, colorless, thin-walled. Pleurocystidia 32–82 × 11–32 μm, utriform, ellipsoid, sublageniform or (sub) cylindrical. Lamella trama regular, 3–10 μm wide, hyaline, colorless, thin-walled. Pileipellis a hymeniderm at yellow-brown sulcate, mainly made up of sphaeropedunculate cells, sometimes ellipsoid or utriform with inconspicuous short pedicels, 21–46 × 13–22 μm, hyaline, with brown hue at base in most cases; other part of pileus with gray hue a cutis, made up of hyaline, almost colorless hyphae, 6–8 μm; pileus trama hyphae densely interwoven, thin-walled, hyaline, yellow-brown to brown, 3–8 μm wide. Sclerocystidia absent. Caulopellis hyphae parallel, 3–9 μm wide, hyaline, thin-walled; hyphae of stipe trama 7–15 μm wide, colorless, thin-walled or slightly thick-walled; caulocystidia unseen, occasionally seen specialized terminal elements. Clamp connection present.

Ecology.

Solitary, subfasciculate, or in small groups, grow on clayey soil in grassy places or decayed wood chips or humus layer in broad-leaf or coniferous forest, particularly under trees or shrubs. Fruiting in August to September. Only known from northeast China, however, quite common.

Other specimens examined.

CHINA • Jilin Province, Changchun City, Jilin Agricultural University , 43°80'78"N, 125°41'67"E, 193 m a. s. l., September 11 th 2021, L. Y. Zhu, HMJAU 60346 (Z 21091102), HMJAU 60361 (Z 21091107), HMJAU 60363 (Z 21091108) ; CHINA • same place with holotype, September 11 th 2021, S. E. Wang, HMJAU 60364 ( Z 21091112 ) ; CHINA • Jilin Province, Changchun City, Jingyuetan National Forest Park , 43°47'31"N, 125°28'34"E, 206 m a. s. l., August 31 st 2021, L. Y. Zhu, HMJAU 60362 (Z 21083131) ; CHINA • Jilin Province, Changchun City, Nanhu Park , 43°51'14"N, 125°17'57"E, 220 m a. s. l., August 17 th 2022, L. Y. Zhu, W. N. Hou, HMJAU 60080 (Z 22081717), HMJAU 60083 (Z 22081703) ; CHINA • Jilin Province, Changchun City, Nanhu Park , 43°50'39"N, 125°18'24"E, 221 m a. s. l., August 17 th 2022, X. Wang, and L. S. Mu, HMJAU 60081 (WX 251) ; CHINA • Liaoning Province, Shenyang City, Zhao Mausoleum , 41°84'98"N, 123°42'16"E, 51 m a. s. l., September 21 st 2024, Q. Q. Dong and Q. Q. Ye, HMJAU 67659 (Z 24092110) ; CHINA • Inner Mongolia Autonomous Region, Tongliao City, Horqin Left Back Banner, Daqinggou National Reserve , 42°47'34"N, 112°10'38"E, 247 m a. s. l., August 23 rd 2022, T. Bau and L. Y. Zhu, HMJAU 60082 (m 247) .

Notes.

The distinguishing characteristics of Parasola eburnea are pileus with relatively lighter color, lamellae free and remote from stipe by pseudocollarium and rhomboid or mitriform basidiospores with slightly eccentric or almost central germ pore. Macroscopically, Parasola eburnea is similar to Parasola lactea and Parasola pseudolactea for the whitish color of pileus especially when young, however, the latter two species could be easily distinguished from Parasola eburnea by their lamellae adnate or nearly free to apex of stipe and pseudocollarium absent, besides size of basidiospores of Parasola pseudolactea is relatively larger, in average 14.0 × 11.3 × 9.7 µm ( Smith and Hesler 1946; Nagy et al. 2010 a; Hussain et al. 2018). Though sharing a close relationship with Parasola eburnea , Parasola crataegi has yellow brown basidiospores with smaller size (avg 7.4 × 6.5 × 4.8 µm) and almost always grow in close vicinity to Crataegus monogyna ( Szarkándi et al. 2017) .

Figures

Figure 17. Basidiomata of species in Clade Lactea in sect. Parasola. a – f Parasola eburnea: a HMJAU 60080, b HMJAU 60083, c HMJAU 60081, d HMJAU 60347, e HMJAU 60082, f HMJAU 60362; g – l Parasola orientolactea: g HMJAU 60348, h HMJAU 60350, i HMJAU 60085, j HMJAU 60091, k HMJAU 60086, l HMJAU 60089; m – o Parasola kuehneri: m HMJAU 60343, n HMJAU 60344, o HMJAU 60077.

Figure 18. Basidiomata and microscopic structures of Parasola eburnea: a basidiomata (HMJAU 60347, HMJAU 60361, HMJAU 60080), b pileipellis (HMJAU 60347), c basidiospores (HMJAU 60347, HMJAU 60080), d basidia (HMJAU 60080), e cheilocystidia (HMJAU 60347, HMJAU 60080), f pleurocystidia (HMJAU 60347, HMJAU 60080), g stipitipellis (HMJAU 60080). Scale bars: 1 cm (a); 10 μm (b – g).