Remotididymella tachibana Manawas., Q.L. Tan & Y.Xia Zhang [as ‘Remotididymella tachibanae’], in Cao et al., (2025)

Index Fungorum number: IF 903596; MycoBank number: MB 664964; Facesoffungi number: FoF 17682; Figs. 1, 2

Etymology – epithet refers to the host, Citrus tachibana a from which the fungus was isolated.

Holotype – ZHKUCC 24–1073. Endophytic on C. tachibana and C. nobilis. Sexual morph: develop after 4 weeks OA medium. Ascomata is black, nearly spherical to inverted pear-shaped, solitary, with a pore opening, semi buried or surface grown on OA medium, 70–150 × 75–140(–160) µm (mean = 125 × 110 µm, n = 30). Asci cylindrical to rod-shaped, hyaline, gradually becoming thinner at the base and top, containing eight ascospores with sizes ranging from 74–97 × 8.7–11.6 µm (mean = 87 × 10 µm, n = 50). Ascospores hyaline, straight or slightly curved, with a blunt top and a wide blunt bottom, septate, septa slightly contracted, upper cell is usually wider than the lower cell, transparent and smooth, 14–17 × 4–5 µm (mean = 16 × 4 µm, n = 50). Asexual morph: not observed.

Culture characteristics – Cultivate on OA medium for 7 days, with a colony diameter of 70 mm (n = 5). The colony is gray, with regular edges and white aerial hyphae. The back is gray to dark gray, radiating. Cultivate on PDA medium for 7 days with a colony diameter of 60 mm (n = 5). The colony is white gray with lush hyphae, with a gray center and a white circular edge. The center of the back is gray to lead black, with regular edges. Cultivate on MEA medium for 7 days, with a colony diameter of 54 mm (n = 5). The colony is white, the hyphae are dense and tightly adhered, with regular edges, white on the back, and a slight orange color in the middle.

Material examined – CHINA, Guangdong Province, Guangzhou, Shaoguan City. On Citrus tachibana, 25 August 2021, Ishara S. Manawasinghe, ZHKUCC 24–1073 (holotype), living cultures ZHKUCC 24–1074, ZHKUCC 24–1075, ZHKUCC 24–1076, ZHKUCC 24–1077, ZHKUCC 24–1078, ZHKUCC 24–1079, ZHKUCC 24–1080 and ZHKUCC 24–1081.

GenBank – ZHKUCC 24–1073: PV486803 (ITS), PV486805 (LSU), PV494565 (rpb2), PV494563 (tub2).

Notes – In the multigene phylogenetic analysis constructed by ITS, LSU, rpb2 and tub2 (Fig. 1), the species in this study formed an independent branch, with a particular sister relationship to R. anemophila, with 94% ML bootstrap support and 0.87 BYPP value. Morphologically, the ascomata of our isolates 70–150 × 75–140(–160) µm (mean = 125 × 110 µm) is bigger than that of R. anemophila 91–121 × 84–86 µm. There is a difference in the size of the asci between 74–97 × 8.7–11.6 µm and R. anemophila 35–102 × 9–11 µm. Based on morphological characteristics and multigene phylogenetic analysis, the strain in this study was identified as a new species.

Figure 1 – The Maximum Likelihood consensus tree inferred from the combined ITS, LSU, rpb2 and tub2 sequences of Epicoccum, Remotididymella and other closely related genera in Didymellaceae. Bootstrap support values for Maximum Likelihood (ML, first value) equal to or greater than 75% and Bayesian posterior prob abilities from MCMC analyses (BYPP, second value) equal to or greater than 0.95 are given above the nodes. The scale bar indicates expected changes per site. The tree is rooted to Neodidymelliopsis xanthina (CBS 168.70) and Neodidymelliopsis achlydis (CBS 256.77). Type strains are indicated with “T”. The newly generated sequences are indicated in red.

Figure 2 – Remotididymella tachibana (ZHKUCC 24–1073, holotype). a, b Colony on OA (front and reverse, 5 d). c, d Colony on MEA (front and reverse, 5 d). e, f Colony on PDA (front and reverse, 5 d). g Ascomata. i Asci. j Ascospores. h Aggregated ascomata on OA. Scale bars: g–j = 10 µm