Colletotrichum musichiangmaiense Gomdola, K. D. Hyde & Jayaward., 2025

Gomdola, Deecksha, Jeewon, Rajesh, McKenzie, Eric H. C., Jayawardena, Ruvishika S., Al-Otibi, Fatimah, Tang, Xia, Wang, Yong, Hyde, Kevin D. & Fu, Li, 2025, Phylogenetic diversity of Colletotrichum species (Sordariomycetes, Glomerellales, Glomerellaceae) associated with plant diseases in Thailand, MycoKeys 119, pp. 137-195 : 137-195

Colletotrichum musichiangmaiense Gomdola, K. D. Hyde & Jayaward. sp. nov.

Figs 1 , 12

Holotype.

MFLU 25-0020 .

Etymology.

The compound epithet refers to the host genus, Musa , from which the species was isolated, and the location, Chiang Mai, where the fungus was collected.

Description.

Associated with leaf blight of Musa sp. Leaf blight elongated, pale brown to brown, surrounded with a dark brown margin. Sexual morph: Not observed. Asexual morph on PDA: Conidiomata 200–1000 µm diam. (x ̄ = 450 µm, n = 10), semi-immersed, scattered or gregarious, globose to subglobose, dark brown to black, exuding creamy orange conidial mass. Setae not observed. Conidiophores formed directly from mycelium, hyaline, aseptate, smooth-walled. Conidiogenous cells 9–16 × 2–6 µm (x ̄ = 13.2 × 4.2 µm, n = 10), hyaline, cylindrical to ampulliform or clavate, straight or flexuous, tapering towards the apex. Conidia 12–19 × 4.5–6 µm (x ̄ = 15.7 × 5.4 µm, n = 30; L / W ratio = 2.9), hyaline, cylindrical to clavate, straight or slightly flexuous, smooth-walled, guttulate, aseptate, mostly with obtusely rounded ends (sometimes tapering towards one end). Appressoria not observed.

Culture characteristics.

Colonies on MEA reaching approximately 75 mm diam. after 7 d of incubation at 25 ° C; mycelium initially greyish white, becoming olivaceous brown with age, elevation flat, cottony, and fluffy, aerial and filamentous with an entire margin.

Specimen examined.

Thailand • Chiang Mai Province, Omkoi District, Yiang Piang Subdistrict , associated with leaf blight of Musa sp. ( Musaceae ), 16 Oct 2019, D. Gomdola DG 385-T 2 ( MFLU 25-0020 , holotype), ex-type MFLUCC 25-0021 .

GenBank accession numbers.

ITS = PV 263308; GAPDH = PV 290913; ACT = PV 297888; and TUB 2 = PV 295628.

Known hosts, distributions, and lifestyles.

Associated with leaf blight of Musa sp. in Thailand (this study).

Notes.

Our isolate ( MFLUCC 25-0021 ) matches the morphological species concept of Colletotrichum ( Jayawardena et al. 2021 a). It forms a distinct lineage (99 % ML and 1.00 PP support; Fig. 1 ), separate from other Colletotrichum species, and does not group within any species complex. Based primarily on its phylogenetic placement and supported by morphological data, we designate our isolate as a new singleton species, Colletotrichum musichiangmaiense , associated with leaf blight of Musa sp. in Thailand.

Figures

Figure 1. Maximum likelihood analysis (IQ-tree) based on a combined dataset of ITS, GAPDH, CHS 1, ACT, TUB 2, H 3, and CAM sequences from dataset 1, which includes all Colletotrichum species. Bootstrap support values (ML ≥ 80 %) and Bayesian posterior probabilities (PP ≥ 0.95) are given above the branches or near the nodes as ML / PP. Hyphens (--) indicate bootstrap support values below 80 % for ML and posterior probabilities below 0.95. The tree is rooted with Monilochaetes infuscans (CBS 869.96) and M. melastomae (CBS 145059). Type, ex-type, and reference species are denoted with T. Our isolates are in bold red font, while our new species are in bold blue font. Different color blocks represent distinct species complexes, with a single color used to denote singleton species.

Figure 12. Colletotrichum musichiangmaiense (MFLU 25-0020, holotype). a. Leaf blight (Musa sp.); b. Top and reverse of colony on MEA after 5 d; c. Spore mass formation on MEA after 21 d; d. Conidiogenesis and developing conidia; e – g. Conidia. Scale bars: 500 μm (c); 10 μm (d – g).