Corynespora chengduensis Y.P. Chen & Maharachch., sp. nov.

Index Fungorum number: IF 901380; Mycobank number: MB 901380; Facesoffungi number: FoF 15113; Fig. 1

Etymology – The name refers to Chengdu, the city where the fungus was collected.

Holotype – HKAS 127168

Saprobic on the decaying wood of an unidentified plant. Sexual morph: not observed. Asexual morph: Hyphomycetous. Colony on natural substrate effuse, dark brown, velvety or spongy, forming widely effused patches. Mycelium partly superficial, immersed in the substrate, composed of branched, septate, subhyaline to dark brown, curved hyphae. Stromata partly superficial, immersed, brown, irregular in shape, pseudoparenchymatous, composed of brown cells. Conidiophores 100–710 μm (x̅=350, n=20) (x̅=140×14, n=40), with a 4–8 μm (x̅=6, n=40) wide blackish-brown scar at the base, formed singly or in a short chain through a wide pore at the apex of the conidiophore, often with proliferation through the apical pore and formation of another conidium at the apex of the proliferation, almost cylindrical but usually slightly and gradually tapering towards the rounded apex and more abruptly towards the truncate base, straight or slightly curved, smooth, subhyaline to golden brown, 0–26-distoseptate, with angular lumina; wall up to 5 μm thick (Fig. 2).

Culture characteristics – Colony on PDA 19 mm diam after 1 week in an incubator under dark conditions at 20 °C, white, circular, surface velvety, with dense mycelium and entire margin; reverse creamy white.

Material examined – China: Sichuan Province, Chongzhou City, Baiyungou, 30°47′52″ N, 103°24′19″ E, elevation 990 m, 27 September 2021, on a decaying branch of an unidentified host, Y.P. Chen, BY13 (HKAS 127168, holotype),ex-type culture UESTCC 22.0153.

GenBank numbers – ITS=OR762653, SSU=OR762654, LSU=OR762655, tef1-α=OR771929, RPB2=OR771930.

Notes – In this study, we isolated and identified a new Corynespora species UESTCC 22.0153, by morphological examinations and multi-locus phylogenetic analysis. The phylogenetic tree shows that the isolate UESTCC 22.0153 forms a separated branch, and C. olivacea (CBS 136917) is the only species close to it. Our species is morphologically different from the C. olivacea by having a longer conidium (54–219 μm vs. 50–105 μm) and more distosepta (0–26 vs. 5–14) (Ellis 1960a, b). In addition, BLASTn analyses of them showed 93% sequence identity (463/500, 6 gaps) for ITS and 98% sequence identity (814/828, 7 gaps) for LSU. Considering the significant differences in morphology and molecular data, we introduce the isolate UESTCC 22.0153 as a new species Corynespora chengduensis.

Figure 1 – Corynespora chengduensis (HKAS 127168, holotype). a–c Colonies on the natural substrate. d–f Conidiophores. The arrow points to the apical pore. g, h Conidiophore bases and stroma cells. i–k Conidiophores, conidiogenous cells and apical conidia. l–y Conidia. z Germinating conidium on PDA. a1, b1 Front and back views of the colony on PDA (1 week). Scale bars: d, z=50 μm, g, i, l, r=20 μm. D applies to e and f. g applies to h. r applies to s–z

Figure 2 – Phylogram generated from maximum likelihood analysis based on a three-locus dataset (LSU, ITS and RPB2) representing Epicoccum indicum (NFCCI 5322) and related species. The scale bar indicates 0.08 changes. The tree is rooted in Neocucurbitaria aquatica (CBS 297.74). Species sampling was based on Hou et al. (2020). One hundred-eleven sequences are included in the analysis which comprises 1850 characters after alignment. ML analysis was performed using a GTR model of site substitution, including GAMMA+P-Invar model of rate heterogeneity and a proportion of invariant sites. Bayesian inference was implemented with the GTR+I+G model. The best RAxML tree with a final likelihood value of−9265.764120 is presented. Estimated base frequencies were as follows: A=0.243820, C=0.240756, G=0.279920, T=0.235504; substitution rates: AC=1.874052, AG=6.412815, AT=2.187577, CG=1.253908, CT=17.584563, GT=1.000000; gamma distribution shape parameter α=0.138623. Bootstrap support values obtained in a complementary Maximum Likelihood analysis (MLBS, right) with RAxML using 1000 pseudoreplicates are provided after the BYPP values (left). Bootstrap support values for ML equal to or greater than 70% and BYPP equal to or greater than 0.95 are given above the nodes. For each terminal, the species name and the voucher/herbarium code are indicated, and new isolate is in blue

Figure 2 – (continued)