Xenodidymella coffeae L. Lu & Tibpromma 2025, sp. nov.

Xenodidymella coffeae L. Lu & Tibpromma sp. nov. Fig. 6 Etymology. The species epithet “ coffeae ” refers to the host plant genus “ Coffea ” from which the fungus was isolated. Diagnosis. Differs from X. clematidis Phukhams., Camporesi & K. D. Hyde, by shorter ostioles and cylindrical conidia. Holotype. HKAS 137610. Description. Saprobic on decaying branch of C. arabica. Teleomorph: Not observed. Anamorph: Conidiomata 50–80 µm high × 50–90 µm diam. (x- = 62 × 70 µm, n = 20), separate or scattered, semi-immersed, black, globose to subglobose or pyriform, pycnidial, with short ostioles. Conidiomatal wall 6–12 µm wide (x- = 9 µm, n = 30), composed of 1–3 layers of light brown to brown cells of textura angularis, heavily pigmented at the outer layers, lined with a hyaline layer bearing conidiogenous cells. Conidiophores inconspicuous or micronematous, often reduced to conidiogenous cells. Conidiogenous cells lining inner cavity, 4–6 × 4–7 µm (x- = 5.3 × 5.4 µm, n = 30), hyaline, globose to ampulliform, enteroblastic, phialidic. Conidia 10–15 × 3–4 µm (x- = 12 × 3.3 µm, n = 30), solitary, hyaline, oblong to cylindrical with rounded ends, aseptate, mostly straight, surface smooth or rough. Culture characteristics. Conidia germinating on PDA within 24 h, colonies reached 6 cm in diameter after two months at 25 ° C, filamentous, filiform margin, smooth, flat, with aerial mycelium, from above, brown at the centre, dark brown at the edge, from below, dark brown to black. Materials examined. China • Yunnan Province, Dali, on a decaying branch of Coffea arabica (Rubiaceae) (26°09'N, 101°91'E, 1415 m alt.), 25 July 2022, LiLu, DL-C 11 (HKAS 137610, holotype), isotype MHZU 23-0064, ex-type living culture KUNCC 24-18339 = KUNCC 24-18340, ex-isotype living culture ZHKUCC 23-0638 = ZHKUCC 23-0639. Notes. In the concatenated phylogenetic analysis, Xenodidymella coffeae shows a close relationship with X. clematidis and X. camporesii D. Pem, Doilom & K. D. Hyde (Fig. 7). Xenodidymella coffeae conforms to the characteristics of Xenodidymella by globose to ampulliform conidiogenous cells and hyaline conidia (Hyde et al. 2020). Xenodidymella coffeae has short ostioles and cylindrical conidia, while X. clematidis has long ostioles with oblong-elliptical or oval conidia (Fig. 6; Phukhamsakda et al. (2020)). Besides, the conidia of our species are larger than those of X. clematidis (10–15 × 3–4 µm vs. 4–8 × 2–5 μm). Xenodidymella camporesii has only been reported based on its teleomorph (Hyde et al. 2020). Based on nucleotide comparisons, X. coffeae (ZHKUCC 23-0638) is different from X. clematidis (MFLUCC 16-1365) by 8 / 482 bp (1.6 %, without gaps) of the ITS, 11 / 786 bp (1.4 %, without gaps) of the LSU; and different from X. camporesii (MFLUCC 17-2309) by 10 / 518 bp (2 %, with one gap) of the ITS, 16 / 890 bp (1.8 %, without gaps) of the LSU and 26 / 282 bp (9 %, without gaps) of the TUB. In addition, the PHI test results (Fig. 22 c) revealed no significant recombination relationships between X. coffeae and its phylogenetically related taxa. This fungus is, therefore, introduced as a new species of Xenodidymella, following the guidelines of Chethana et al. (2021) and Pem et al. (2021).