Colletotrichum tomentosae J.W. Liu, Manawas. & M. Luo, 2023

Liu, Jia-Wei, Manawasinghe, Ishara S., Liao, Xuan-Ni, Mao, Jin, Dong, Zhang-Yong, Jayawardena, Ruvishika S., Wanasinghe, Dhanushka N., Shu, Yong-Xin & Luo, Mei, 2023, Endophytic Colletotrichum (Sordariomycetes, Glomerellaceae) species associated with Citrus grandis cv. " Tomentosa " in China, MycoKeys 95, pp. 163-188 : 163

Colletotrichum tomentosae J.W. Liu, Manawas. & M. Luo sp. nov.

Fig. 2

Etymology.

The epithet refers to the cultivar of the host plant - Citrus grandis cv. “Tomentosa”.

Holotype.

ZHKUCC 21-0103.

Description.

Endophytic in C. grandis cv. “Tomentosa” leaf. Sexual morph: not observed. Asexual morph: Conidiophores 20-40 × 3-5 μm (x- = 29.8 ± 5.5 × 3.7 ± 0.6 μm, n = 30), hyaline, cylindrical, 1-3-celled, unbranched or branched at the base. Conidia 10-20 × 3-6 μm (x- = 12.5 ± 1.6 × 4.4 ± 0.6 μm, n = 50), 1-2-guttulate, aseptate, straight, hyaline, smooth-walled, middle part cylindrical both ends obtuse, middle part occasionally shrinkage or bulging. Appressoria 5-15 × 5-10 μm (x- = 10 ± 1.8 × 7 ± 1.5 μm, n = 50) solitary or in loose groups, light brown to medium brown, Ellipsoidal to subcircular or irregular-shaped.

Cultural characteristics.

Colonies on PDA reach 70 mm diam. in seven days, with 10-11 mm/day (x- = 10 mm, n = 6) growth rate. Colonies flat with entire margin, floccose cottony, surface grey in the centre with glaucous margin. Reverse buff in the centre with off-white margin.

Material examined.

China, Guangdong Province, Huazhou , isolated from a healthy leaf of Citrus grandis cv. “Tomentosa”, May 2019, Y.X. Shu, (dried cultures ZHKU 21-0088 holotype); ex-type culture ZHKUCC 21-0103 (= CGMCC 3.24128), ex-isotype ZHKUCC 21-0104, ZHKUCC 22-0041 ).

Notes.

In the phylogenetic analysis of combined six genes, Colletotrichum tomentosae formed an independent clade (Fig. 1 ). This species is phylogenetically distinct from C. syzygicola . Morphologically, appressoria developed by C. syzygicola (DNCL021; Udayanga et al. (2013)) are longer than C. tomentosae (5-15 × 18-24 μm vs. 18-24 μm). Colletotrichum tomentosae has longer conidiophores (20-40 × 3-5 vs. 12-16 × 4-5 μm). This species can be distinguished from C. syzygicola by 32 nucleotide differences (1/511 in the ITS region, 2/229 in the gapdh region, 7/242 in the act region and 22/906 in the gs region). The PHI test revealed no significant evidence for a recombination (p = 1.0) event amongst C. syzygicola and its closely-related taxa (Fig. 3 ). Therefore, we have described this fungus as a novel species.

Figures

Figure 1. The most parsimonious tree of the Colletotrichum gloeosporioides complex developed using combined act, chs- 1, gapdh, ITS, β- tubulin and gs sequences. Colletotrichum boninense and C. hippeastri were used as outgroup taxa. Bootstrap values equal to or greater than 60 % in MP and ML and BP equal to or greater than 0.95 are shown as MP / ML / BP above the respective node. The isolates belonging to the current study are given in blue for known species and new species are shown in red. Ex-type strains are noted with T.

Figure 2. Colletotrichum tomentosae (ZHKUCC 21 - 0103, holotype) A, B upper and reverse side of cultures on PDA seven days after inoculation C, D conidiophores with developing conidia E, F conidia G, H appressoria. Scale bars: 10 μm (C-H).

Figure 3. PHI analysis of combined ITS, gapdh, chs- 1, act and β- tubulin sequence data. PHI test result (Φw) <0.05 indicates significant recombination within the dataset.