Trechispora perminispora S.L. Liu & L.W. Zhou, sp. nov.

Index Fungorum number: IF 901061; Mycobank number: MB 901061; Facesoffungi number: FoF 14814; Figs. 1, 2, 3

Etymology – perminispora (Lat.) referring to very small basidiospores.

Holotype – LWZ 20190816-39a (HMAS).

Diagnosis – Differing from other species of Trechispora in the smallest basidiospores.

Basidiomes annual, resupinate, effused, thin, soft and fragile, easily separated from substrates, up to 15 cm long, 3 cm wide. Subiculum too thin to be seen. Hymenophore grandinioid with numerous small aculei, white to cream when fresh, cream to buff when dry. Margin white, slightly fimbriate, up to 0.5 mm wide.

Hyphal system monomitic; generative hyphae with clamp connections. Tramal hyphae distinct, hyaline, thin-walled, frequently branched, smooth, interwoven, 3–3.5 μm in diam. Cystidia absent. Crystals aggregated, rhomboidal flakes. Basidia cylindrical with a slight median constriction, hyaline, thin-walled, with four sterigmata and a basal clamp connection, 9–12×4–4.5 µm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores ellipsoid, hyaline, slightly thick-walled, verrucose, IKI–, CB–, (2.5–)2.6– 3(–3.2)×1.8–2.1(–2.3) µm, L=2.8 µm, W=2 µm, Q=1.4 (n=30/1).

Material examined – China, Sichuan Province, Ebian Yi Autonomous County, Heizhugou National Nature Reserve, on fallen branch of angiosperm, 16 August 2019, L.W. Zhou, LWZ 20190816-39a (HMAS, holotype).

GenBank numbers – ITS=OM523525, LSU=OM339329.

Notes – In Trechispora, basidiospores are mostly more than 3.5 µm in length and 2.5 µm in width. Two species, viz. Trechispora microspora and T. minispora, have smaller basidiospores than these sizes (Larsson 1996; de MeirasOttoni 2021). However, even in comparison with these two species, T. perminispora has smaller basidiospores, which make it distinguished in this genus.

Figure 1 – Basidiomes of Trechispora perminispora (LWZ 20190816- 39a, holotype). Scale bars: a=1 cm, b=1 mm

Figure 2 – Microscopic structures of Trechispora perminispora (LWZ 20190816-39a, holotype). a A vertical section of basidiomes. b Basidia. c Basidiospores. Scale bars: 10 μm

Figure 3 – Scanning electron micrograph of basidiospores of Trechispora perminispora (LWZ 20190816-39a, holotype). Scale bars: 2 μm