Cyathus pyristriatus – Facesoffungi number: FoF 02385

Cyathus pyristriatus B. Thongbai, C. Richt. & M. Stadler

MycoBank number: MB817167 Facesoffungi number: FoF02385

Etymology: Named for its production of pyristriatins A and B.

Holotype: MFLU15-1416.

Saprobic on rotten wood in forest with Fagaceae. Basidiomata clavate to broadly obconic, without stipe, 5.5–7 mm high and 4–6 mm diam., wide at the top, external peridium covered with shaggy or fluffy yellowish-brown or buff hairs with age, surface of inner peridium grey, darkening with age, distinctly plicate. Peridioles 3–3.5 mm in diam. wide, greyish-brown to dark grey covered with minute, greyish to greyish-brown hairs. Basidiospores 14–17 x 8–10 um (av. = 15.18 9 8.12, Q = 1.5–1.91, Qm = 1.70, n = 40), ellipsoid to broadly ellipsoid, some ovoid, rarely subglobose, hyaline, smooth, thin-walled, 1.5–3 um thick. Basidia not observed. Clamp connections present in all tissues
including the mycelial culture.

Material examined: THAILAND, Chiang Mai Province, Mae-Taeng District, near the Mushroom Research Centre (http://www.mushroomresearchcentre.com/), N1907.2000 E9844.0440, 12 August 2014, Thongbai, Richter & Stadler M68 (MFLU 15-1416, holotype), ex-type culture MFLUCC14-0770.

Notes: Cyathus pyristriatus closely resembles C. striatus (Huds.) Willd. 1787 in the account of shaggy or fluffy yellowish-brown or buff hairs of peridium, distinctly plicate inner peridium, while peridioles are greyish-brown to dark grey. Based on morphological comparison between C. striatus and C. pyristriatus the latter has smaller basidioma and also smaller ellipsoid basidiospores. However, peridioles are covered with a distinctive minutely greyish to greyish-brown hairs, while peridioles of C. striatus are smooth. Remarkably, C. striatus was reported producing pale to dark pigments from basidiomata, which vary in size (Kuo 2014; Wood and Stevens 2015). An initial BLAST search of the ITS nucleotide sequence from NCBI database (http://www.ncbi.nlm.nih.gov/) gave the closest hit to a Cyathus striatus strain (EU784194) with a maximum similarity of 94.5 % (Brock et al. 2009). The BLAST search of the LSU nucleotide sequence of C. pyristriatus resulted in a high degree similarity of 98.8 % (DQ071742) with C. striatus (Garnica et al. 2007). Illustrates the phylogenetic relationships of C. pyristriatus, C. striatus, and other Cyathus species. The ITS based phylogenies clearly depict that our new taxon belongs to the genus Cyathus. A close affinity between C. pyristriatus and C. stercoreus collected from China, is also noted with high support. Cyathus stercoreus, however, differs in having a smooth surface of inner peridium and larger globose to oval basidiospores (Zhao et al. 2008). The ex-type culture of the new species also produces novel terpene alkaloid antibiotics named pyristriatins, which have never been found in Cyathus, despite the fact that this genus has been evaluated intensively for secondary metabolites for several decades (Richter et al. 2016).