Coryneum fagi C.M. Tian & N. Jiang, sp. nov.
Index Fungorum number: IF 558647; MycoBank number: MB 558647; Facesoffungi number: FoF 09957; Fig. 117
Etymology – Named after the host genus, Fagus.
Holotype – BJFC-S1782
Saprobic or weak pathogenic branches of Fagus sp. Sexual morph Undetermined. Asexual morph Conidiomata 0.2–0.6 mm wide, 0.2–0.8 mm high, acervular, solitary, erumpent through the outer periderm layers of the host, scattered, surface tissues above slightly domed, formed of brown cell, thick-walled textura angularis. Conidiophores 60–125 μm long, 4–7 μm wide, cylindrical, apically pale brown, paler at the base, smooth, septate, unbranched, arising from basal stroma. Conidiogenous cells annellidic, integrated, terminal, cylindrical, expanding towards the apices, pale brown, smooth, with 1–3 slightly percurrent proliferations. Conidia 45–75×10–15.5 μm (x̅=62.5×12 μm, n=20), variable in shape, curved, broadly fusiform to fusiform, cylindrical or clavate, dark brown, smooth-walled, 6–12-distoseptate, apical cell with a hyaline tip, truncate and black at the base.
Material examined – CHINA, Sichuan Province, Yaan City, on dead branches of Fagus sp., 10 September 2020, N. Jiang (BJFC-S1782, holotype), ibid. BJFC-S1783 (isotype).
GenBank numbers – BJFC-S1782: ITS = MW144761, LSU = MW144953; BJFC-S1783: ITS = MW144762, LSU= MW144954.
Notes – Coryneum species were mainly named based on host associations and morphology, especially conidial characters, due to the absence of molecular data for most species (Jiang et al. 2018). In the present study, we discovered Coryneum species from a new host genus, Fagus (Fig. 1). The DNA was extracted directly from the conidiomata on branches and ITS and LSU sequences were amplified, sequenced and compared with known species (Fig. 2). Coryneum fagi was phylogenetically close to C. ilicis, but they can be distinguished by the wider conidia of C. fagi (C. fagi=45–75×10–15.5 μm vs. 82–105×9.5–12.5 μm in C. ilicis) (Jiang et al. 2019).
Figure 1 – Coryneum fagi (BJFC-S1782, holotype). a Conidiomata on the dead branch of Fagus sp. b Cross section of conidioma. c–e Developing conidia from conidiogenous cells. f–j Conidia. Scale bars: b=100 μm, c–j=10 μm
Figure 2 – Phylogram generated from RAxML analysis based on combined LSU, ITS, TEF1-α and RPB2 sequence data of Coryneum. Related sequences were obtained from GenBank. Thirty-two strains are included in the combined analyses, which comprise 4690 characters (1500 characters for ITS-LSU, 232 characters for TEF1-α, 1079 characters for RPB2) after alignment. Stilbospora macrosperma (CBS 115073) and Stegonsporium pyriforme (CBS 120522) are used as the outgroup taxa. The tree topology of the ML analysis was similar to the BI. The best scoring RAxML tree with a final likelihood value of−12745.413163 is presented. The matrix had 817 distinct alignment patterns, with 18.15% of undetermined characters or gaps. Maximum likelihood bootstrap support values equal to or greater than 50% (MLBS, left), and Bayesian posterior probabilities equal to or greater than 0.90 (BYPP, right) are given at the nodes. The newly generated sequences are in blue bold