Epicoccum terminosporum Kular. & K.D. Hyde, sp. nov.
Index Fungorum number: IF 900414; MycoBank number: MB 900414; Facesoffungi number: FoF 14170; Fig. 1
Etymology – Based on the terminal or acropleurogenous conidiogenous cells.
Saprobic on leaves of Livistona chinensis (Jacq.) R.Br. ex Mart. Appears as black, scattered spots. Asexual morph: Conidiomata 180–200 × 230–260 μm (x=190 × 243 μm, n=10), pycnidial, solitary, scattered, immersed to erumpent, compressed-globose, black, coriaceous, ostiolate, apapillate. Conidiomata wall 20–30 μm (x=23 μm, n=10), pseudoparenchymatous, 3–6 cell layered, composed of thick-walled, long, compressed, brown cells of textura angularis. Conidiogenous cells 15–20×5–10 μm (x=18×8 μm, n=20), terminal or acropleurogenous, enteroblastic, phialidic, doliiform to ampulliform, hyaline, thin-walled. Conidia 4–5 × 3–4 μm (x=4.5 × 3.3 μm, n=20), oblong to oval, rounded at ends, hyaline, aseptate, guttules absent. Sexual morph: Not observed.
Culture characters – Colonies on PDA reaching 3 cm diam. after 10 days in dark at 25 °C, floccose, flat, circular, smooth margin, white, woolly aerial mycelia concentrate at the centre, reverse off-white, no pigments produced.
Material examined – China, Guangdong Province, Guangzhou City, South China Botanical Garden (23° 11′ 12″ N 113° 21′ 51″ E), on leaves of Livistona chinensis (Arecaceae), 8 June 2021, N.D. Kularathnage, NDK 22N (MHZU 22-0129, holotype), ex-type cultures ZHKUCC 22-0224, ZHKUCC 22-0229.
GenBank numbers – LSU: OR164967, OR164968, ITS: OR164939, OR164940, β-tubulin: OR166315, OR166316, rpb2: OR166290, OR166291.
Notes – This phoma-like collection (MHZU 22-0129) is phylogenetically affiliated with Epicoccum bambusae (ML/BI=89/0.90, Fig. 2). The nucleotides in ITS, LSU and β-tubulin genes differ between these two isolates as 1.26%, 0.53%, 5.7% respectively. Our collection (MHZU 22-0129) morphologically differs from E. bambusae by having immersed to erumpent, compressed-globose conidiomata, terminal or acropleurogenous, enteroblastic conidiogenous cells and oblong to oval, hyaline, aguttulate conidia. Our collection (MHZU 22-0129) is a foliar saprobe while Epicoccum bambusae was collected from bamboo culms. Therefore, we introduce this collection as Epicoccum terminosporum.
Figure 1 – Epicoccum terminosporum (MHZU 22-0129, holotype). a, b Host plant and name board. c, d Conidiomata appear on host substrate. e Vertical section of a conidioma. f–h Conidiogenous cells attached to conidia. i Conidia. j Surface view of colony on PDA. k Reverse view of colony on PDA. Scale bars: e=100 μm, f–h=25 μm, i=10 μm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU, β-tubulin and rpb2 sequence data which comprised 2321 characters (ITS=476, LSU=941, β-tubulin=333, rpb2=571). The best scoring RAxML tree with a final likelihood value of − 8757.729573 is presented. The matrix had 422 distinct alignment patterns, with 7.29% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.245371, C=0.247182, G=0.273997, T=0.233450; substitution rates: AC=1.183550, AG=3.903447, AT=1.6002, CG=0.898268, CT=11.877761, GT=1.0; gamma distribution shape parameter α=0.150149. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Leptosphaeria doliolum (CBS 616.75, CBS 505.75)