Phaeoacremonium chinensis Senan. & Kular., sp. nov.

Index Fungorum number: IF 900446; MycoBank number: MB 900446; Facesoffungi number: FoF 14201; Fig. 1

Etymology – in reference to the region where sample has been collected, China.

Saprobic on decaying wood. Sexual morph: Undetermined. Asexual morph: Mycelium 2.5–3.5 µm wide, consisting of branched, septate, single hyphae, subhyaline to pale brown, smooth-walled. Conidiophores 20–25 µm long, 2.5–3.5 µm wide, arising from aerial or submerged hyphae, branched, each conidiophores often ending in a single terminal conidiogenous cells, occasionally also with lateral conidiogenous cells, erect, up to 4-septate, subhyaline to pale brown, paler towards the tip, smooth. Conidiogenous cells 2–3 µm long, 1–1.5 µm wide, terminal or lateral, monophialidic, smooth, mostly subulate, some navicular, tapering towards the apex, pale brown to olivaceous, collarettes. Conidia 3.5–4.5×2–2.5 µm, hyaline to olivaceous, allantoid or subcylindrical, unicellular.

Culture characteristics – Colonies reaching 5 cm diam. after 10 days at 25 °C. Colonies on PDA flat, circular, filiform margin, woolly with plenty of aerial mycelia, initially pale brown become dark brown when sporulate; reverse dark brown with filamentous hyphae at margin.

Material examined – China, Guangdong Province, Guangzhou City, Haizhu District, Xiaogang park, on bark of unidentified host, 5 April 2021, N.D. Kularathnage, NDK 2-1, (MHZU 22-0083, holotype), ex-type culture ZHKUCC 22-0149.

GenBank numbers – ITS: OR164913, LSU: OR164958, tef1-α: OR166282.

Note – The combined ITS, LSU and β-tubulin gene analyses (Fig. 2) shows that our collection is close to Phaeoacremonium aquaticum and P. rubrigenum, forming a distinct clade with ML/BI=99%/1.00 statistical support. Phaeoacremonium aquaticum is only described from its sexual morph and this species was reported from Yunnan and Beijing Provinces in China on submerged wood in freshwater streams (Hu et al. 2012). Our collection shows 1.67% nucleotide differences in ITS with P. aquaticum and sequences of other genes are unavailable for P. aquaticum.

Figure 1 – Phaeoacremonium chinensis (MHZU 22-0083, holotype). a Surface view of the colony on PDA. b Reverse view of the colony on PDA. c–f Conidiophores attached to conidia. g Conidia. Scale bars: c–g=10 µm

Figure 2 – The best scoring RAxML tree with a final likelihood value of − 20,111.099446 for combined dataset of ITS (415 bp) and LSU (1098 bp) sequence data. The topology and clade stability of the combined gene analyses was compared to the single gene analyses. The tree is rooted with Pleurostoma richardsiae (CBS 270.33). The matrix had 951 distinct alignment patterns with 40.73% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.224327, C=0.285250, G=0.263495, T=0.226927; substitution rates AC=1.643769, AG=4.356590, AT=1.491903, CG=1.297038, CT=5.507338, GT=1.0; gamma distribution shape parameter α=0.220723. Ex-type strains are in bold and newly generated sequences are in blue bold. Bootstrap support for ML equal to or greater than 50% and BI equal to or greater than 0.90 are given above the nodes