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

Figs 17 g – l , 19

Diagnosis.

Pileus lacteous to cream at margin, light brown at center; basidiospores 11.0–11.7 × 11.3–11.8 × 6.9–7.4 μm, with variable shapes, ranging from triangular, pentangular to heart-shape in front view, sometimes with two germ pore, yellow-brown or olive-brown; basidia dimorphic, 2 - spored; cheilocystidia 25–47 × 9–22 μm, utriform, ellipsoid, sublageniform, fusiform or clavate; pleurocystidia 40–65 × 13–26 μm, ellipsoid or sublageniform; pileipellis a hymeniderm mixed with clavate and ellipsoid cells; sclerocystidia absent.

Etymology.

The specific epithet “ orientolactea ” is combined with “ oriento ” (eastern) which refers the occurrence of the new species in the Far East and “ lactea ” meaning the close affinity to Parasola lactea .

Type.

CHINA • Jilin Province, Changchun City, National Forest Park , 43°79'65"N, 125°45'51"E, 202 m a. s. l., August 23 rd 2021, L. Y. Zhu, HMJAU 60350 (Z 21082316, holotype) .

Description.

Pileus 4–7 × 5–9 mm when still closed, 8–13 mm when mature, at first ovoid or ellipsoid, finally almost flattened, often with a depressed disc at center; dry; lacteous to cream at margin and sometimes with brown hue in center when young, pale gray at age, sometimes with water-soaking texture; sulcate-striate almost up to center. 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 = 26–39, I = 0 or 1, first white to beige, pale gray to purple-gray when expanded; hardly deliquescent with age. Stipe 35–81 × 1–2 mm, cylindrical, hollow, equal or attenuate towards the apex, white to pale gray, glabrous. Spore print without being recorded.

Basidiospores [64, 5, 3] (10.2 –) 11.0–11.7 (– 14.6) × (10.6 –) 11.3–11.8 (– 13.7) × (6.0 –) 6.9–7.4 (– 8.1) μm, Q 1 = 0.92–1.07, Q 2 = 1.45–1.86, av. Q 1 = 0.98, av. Q 2 = 1.64; mostly in triangular, pentangular or heart-shape with apical papilla and convex base and occasionally in broad heart-shape or subrectangle when with two germ pore in front view, flattened, ellipsoid to narrow ellipsoid or narrow fabiform in side view; smooth, yellow-brown or olive-brown, with yellow-brown oil droplet; inamyloid; germ pore eccentric, 2.3–4.3 μm wide. Basidia dimorphic, 15–30 × 9–12 μm, sterigma 4–8 μm, clavate, occasionally constricted in middle part, hyaline, 2 - spored, surrounded with 4–6 pseudoparaphyses; subhymenium composed of subglobose, ellipsoid, oblong or cylindrical elements, 7–21 × 8–16 μm. Cheilocystidia 25–47 × 9–22 μm, abundant, utriform, ellipsoid, sublageniform, fusiform or clavate, smooth, colorless, thin-walled. Pleurocystidia 40–65 × 13–26 μm, ellipsoid or sublageniform. Lamella trama regular, 4–12 μm wide, hyaline, colorless, thin-walled. Pileipellis a hymeniderm at yellow-brown sulcate, mainly made up of clavate cells, sometimes ellipsoid or utriform with inconspicuous short pedicels, 35–64 × 10–19 μm, hyaline, sometimes with light-brown hue at base; other part of pileus with gray hue a cutis, made up of hyaline, almost colorless hyphae, 4–10 μm; pileus trama hyphae densely interwoven, thin-walled, hyaline, colorless or with pale brown hue, 6–8 μm wide. Sclerocystidia absent. Stipipellis hyphae parallel, 3–6 μm wide, hyaline, thin-walled, often diverticulate; hyphae of stipe trama 8–21 μm wide, colorless, thin-walled; caulocystidia absent. Clamp connection and pseudoclamp present.

Ecology.

Solitary, subfasciculate, or in small groups, grow on clayey soil in lawns or decayed wood chips or rotten wood in broad-leaf forest with Crataegus , Ulmus , Robinia and Quercus mongolica . August to September. Only known from China, however, quite common.

Other specimens examined.

CHINA • Same place with holotype, August 31 st 2021, L. Y. Zhu, HMJAU 60348 (Z 21083131) ; • August 23 rd 2021, L. Y. Zhu, HMJAU 60349 (Z 21082317) ; • August 26 th 2021, L. Y. Zhu, Q. Q. Dong, and Q. Q. Ye, HMJAU 60351 (Z 21082326) ; • August 24 th 2021, L. Y. Zhu, X. Wang, F. Guo, and L. S. Mu, HMJAU 60352 (Z 21082407) ; • September 18 th 2021, L. Y. Zhu and Q. Q. Ye, HMJAU 60091 (Z 21091821) ; • August 18 th 2022, L. Y. Zhu and W. N. Hou, HMJAU 60085 (Z 22081806), HMJAU 60086 (Z 22081807) ; CHINA • Jilin Province, Changchun City, Changchun Zoological and Botanical Park , 43°51'49"N, 125°19'46"E, 208 m a. s. l., August 23 rd 2022, X. Wang, HMJAU 60078 (WX 379) ; CHINA • Jilin Province, Yanbian Korean Autonomous Prefecture, Antu County, Jianshui River National Wetland Park , 42°24'50"N, 128°07'04"E, 726 m a. s. l., August 1 st 2022, H. B. Song and S. E. Wang, HMJAU 60088 (S 22080103) ; CHINA • Inner Mongolia Autonomous Region, Tongliao City, Horqin Left Back Banner, Daqinggou National Reserve , 42°47'35"N, 112°11'34"E, 223 m a. s. l., August 23 rd 2022, T. Bau and L. Y. Zhu, HMJAU 60079 (Z 2208 C 3) ; CHINA • Jilin Province, Jilin City, Lake Songhua Scenic Area , 42°72'09"N, 126°70'79"E, 230 m a. s. l., September 20 th 2024, X. Y. Zhou, HMJAU 67658 (ZXY 24092003) ; CHINA • Guizhou Province, Guiyang, Guiyang Forest Park , 26°33'31"N, 106°45'20"E, 1187 m a. s. l., September 28 th 2021, T. Bau and L. Y. Zhu, HMJAU 60089 (Z 21092831) ; CHINA • Guizhou Province, Guiyang City, Changpoling National Forest Park , 26°39'31"N, 106°40'06"E, 1336 m a. s. l., September 29 th 2021, T. Bau and L. Y. Zhu, HMJAU 60090 (Z 21092922) .

Notes.

Macroscopically, Parasola orientolactea exhibits morphological similarities to Parasola lactea and Parasola pseudolactea . However, the newly discovered species could be readily distinguished from the latter two species by several characteristics: The presence of 2 - spored basidia, yellow-brown or olive-brown basidiospores that sometimes exhibit two germ pores, and the polymorphic cheilocystidia. Consistent with phylogenetic results, our microscopic observation suggested that Parasola orientolactea is the transition species between Parasola lactea and Parasola pseudolactea (as detailed in Table 4 ). These three species appear to have relatively restricted geographic distributions, with Parasola lactea occurring in Europe, Parasola pseudolactea in Central Asia (reported in Pakistan), and Parasola orientolactea in East Asia (specifically China) ( Smith and Hesler 1946; Uljé 2005; Nagy et al. 2010 a; Hussain et al. 2018). Although BLAST analysis revealed over 98 % sequence similarity among these species, both morphological and phylogenetic evidence strongly support their classification into three distinct clades. Notably, these three species share a unique characteristic within the genus Parasola — the absence of pigment in their pileipellis cells.

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 19. Basidiomata and microscopic structures of Parasola orientolactea: a basidiomata (HMJAU 60086, HMJAU 60350), b pileipellis (HMJAU 60086, HMJAU 60090), c basidiospores (HMJAU 60086, HMJAU 60090, HMJAU 60350), d basidia (HMJAU 60350, HMJAU 60349), e cheilocystidia (HMJAU 60086, HMJAU 60350), f pleurocystidia (HMJAU 60086, HMJAU 60350), g stipitipellis (HMJAU 60350). Scale bars: 1 cm (a); 10 μm (b – g).