Polyporus minutissimus Q. Y. Zhang, Z. W. Zheng & F. Wu, 2024

Zheng, Zi-Wei, Zhang, Qiu-Yue, Zhang, Li-Rong, Yuan, Hai-Sheng & Wu, Fang, 2024, Morphological and molecular data reveal Cerrena caulinicystidiata sp. nov. and Polyporus minutissimus sp. nov. in Polyporales from Asia, MycoKeys 106, pp. 1-21 : 1-21

Polyporus minutissimus Q. Y. Zhang, Z. W. Zheng & F. Wu sp. nov.

Figs 5 , 6

Holotype.

China • Zhejiang Province, Hangzhou, Yuhang District, Luniao Town ; 30 ° 25 ' 50 " N, 119 ° 42 ' 38 " E; 158.47 m a. s. l.; 9 Jun. 2023; on ground of Bamboo forest; F. Wu leg., Wu 971 ( BJFC 040963 , holotype).

Etymology.

Minutissimus (Lat.): Referring to the species having tiny basidiocarps.

Description.

Basidiocarps. Annual, centrally stipitate, solitary, fleshy to soft leathery when fresh, becoming fragile when dry. Pilei flat with a depressed center or infundibuliform, up to 1.5 cm in diam and 0.5–1 mm thick. Pileal surface cream to buff yellow when dry, glabrous, occasionally zonate and with radially aligned stripes; margin sharp, incurved upon drying. Pore surface cream when dry; pores angular, 6–9 per mm; dissepiments thin, entire. Context buff cream to pale neutral when dry, fragile upon drying, up to 0.5 mm thick. Tubes white to cream when dry, decurrent, up to 0.5 mm thick. Stipe dark violet, glabrous, 0.3–0.5 cm long and 1–2 mm in diam.

Hyphal structure. Hyphal system dimitic; generative hyphae bearing clamp connections, thin-walled, hyaline; skeleton-binding hyphae thick-walled with a wide lumen, with arboriform branches, IKI –, CB +; tissue unchanged in KOH.

Context. Generative hyphae frequent, colorless, thin-walled, 2.5–4 μm in diam; skeleto-binding hyphae dominant, colorless, thick-walled with a wide lumen, moderately branched, strongly interwoven, 2–4.5 μm diam.

Tubes. Generative hyphae frequent, colorless, thin-walled, 2–3 μm in diam; skeleto-binding hyphae dominant, colorless, thick-walled with a wide lumen, moderately branched, interwoven, 1–3 μm in diam. Cystidia and cystidioles absent. Basidia clavate, with four sterigmata and a basal clamp connection, 22–28 × 7–9 μm; basidioles in shape similar to basidia, but slightly smaller.

Stipe. Generative hyphae frequent, colorless, thin-walled, rarely branched, 3–4 μm in diam; skeleto-binding hyphae dominant, colorless, thick-walled with a wide lumen, moderately branched, interwoven, 1.5–4 μm in diam.

Basidiospores. Basidiospores cylindrical to oblong, colorless, thin-walled, smooth, IKI –, CB –, 5–9.2 (– 10) × (2 –) 2.2–4 (– 4.2) μm, L = 7.30 μm, W = 3.23 μm, Q = 2.25–2.27 (n = 60 / 2).

Additional specimen examined

(paratype). China • Zhejiang Province, Hangzhou, Yuhang District, Luniao Town ; 30 ° 25 ' 50 " N, 119 ° 42 ' 38 " E; 155.11 m a. s. l; on ground of bamboo forest, 9 Jun. 2023; F. Wu leg., Wu 970 ( BJFC 040962 ) .

Figures

Figure 5. Basidiocarps of Polyporus minutissimus (Holotype, Wu 971).

Figure 6. Microscopic structures of Polyporus minutissimus (Wu 970 / Wu 971) a basidiospores b basidia and basidioles c hyphae from trama.