Colletotrichum juglandicola Y. Zhang ter. & L. Zhang, 2023

Zhang, Lin, Yin, Yue-Qi, Zhao, Li-Li, Xie, Yu-Qing, Han, Jing & Zhang, Ying, 2023, Two new species of Colletotrichum (Glomerellaceae, Glomerellales) causing walnut anthracnose in Beijing, MycoKeys 99, pp. 131-152 : 131

Colletotrichum juglandicola Y. Zhang ter. & L. Zhang sp. nov.

Fig. 3

Etymology.

Named from " Juglans ", in reference to the host genus.

Description.

Sexual morph not observed. Asexual morph developed on MEA. Conidiomata acervular, yellow to light brown, bearing conidial masses. Conidiophores hyaline, smooth-walled, septate, branched. Setae medium to dark brown, smooth to finely verruculose close to the tip, the tip rounded, 1-3 aseptate, 60-107.2 μm long. Conidiogenous cells 19.5-38.9 × 2.8-3.9 μm (mean SD = 28.6 ± 1.2 × 3.3 ± 0.1 μm, n = 20), subcylindrical, straight to curved. Conidia 14.6-20.0 × 4.2-6.6 μm (mean SD = 17.1 ± 1.0 × 5.2 ± 0.4 μm, L/W radio = 3.3, n = 100), hyaline, smooth-walled, subcylindrical, both ends round, 1-3-guttulate, contents granular. Appressoria 5-8.3 × 3.3-6.7 μm (mean SD = 6.3 ± 0.2 × 5.2 ± 0.2 μm, L/W radio = 1.2, n = 20), medium to dark brown, variable in shape, often smooth-walled, subglobose, ovate to broadly elliptical in outline.

Culture characteristics.

Colonies on MEA, flat, with entire margin, hyaline, 65-72 mm diam. in 7 d. The colonies are round, white, the edges are flat and the aerial hyphae are lush. Myxospores are orange. The colony diameter reached 63-65 mm on PDA. The colonies are round, green-grey, the edges are flat and the aerial hyphae are lush.

Additional specimens examined.

China, Beijing, Changping District, Heishanzhai Village , from leaf of Juglans regia L., Y. Zhang and L. Zhang, 26 August 2021 (holotype HSG826-P5; ex-type living culture: CGMCC3.24312) . CHINA, Beijing, Huairou District, Shuichangcheng Village , from leaf of Juglans regia L., Aug 2021, Y. Zhang and L. Zhang (Paratype SCCY826-22; living culture: CGMCC3.24313) . CHINA, Beijing, Haidian District, Jiufeng Village , from fruit of Juglans regia L., Aug 2021, Y. Zhang and L. Zhang (Paratype JFG826-P4; living culture CGMCC3.24311) . China, Beijing, Changping District, Yanshou Village , from fruit of Juglans regia L., Aug 2021, Y. Zhang and L. Zhang (Paratype YSG826-R1; living culture CGMCC3.24309) . CHINA, Beijing, Changping District, Yanshou Village , from leaf of Juglans regia L., Aug 2021, Y. Zhang and L. Zhang (Paratype YSY826-2: living culture CGMCC3.24310) .

Notes.

Phylogenetic analysis of a concatenated five loci dataset indicated that the clade of Colletotrichum juglandicola nested in the clade of C. gloeosporioides species complex and was closely related, but independent to C. citrulli , C. dimorphum , C. gloeosporioides and C. nanhuaensis ( Cannon et al. 2008; Guo et al. 2022; Yu et al. 2022). Colletotrichum citrulli was reported from Citrullus lanatus ( Cucurbitaceae ) in China ( Guo et al. 2022). Morphologically, C. juglandicola differed from C. citrulli by having longer conidia and setae and smaller appressoria (Table 2 ) ( Guo et al. 2022). Colletotrichum dimorphum was reported from Ageratina adenophora ( Asteraceae ) in China ( Guo et al. 2022). Morphologically, C. juglandicola differed from C. dimorphum by having setae, shorter appressoria and longer conidia ( Yu et al. 2022) (Table 2 ). Morphologically, C. juglandicola differed from C. gloeosporioides or C. nanhuaensis by having longer conidia ( Cannon et al. 2008; Guo et al. 2022) (Table 2 ). Colletotrichum nanhuaensis was reported from Ageratina adenophora ( Asteraceae ) in China ( Guo et al. 2022) (Table 2 ). The PHI test (Φw = 1.0) detected no significant recombination between related isolates or species (Fig. 2A ).

Figures

Figure 2. The result of the pairwise homoplasy index (PHI) tests of closely-related species using both LogDet transformation and splits decomposition A, B the PHI of C. juglandicola (A) or C. peakense (B) and their phylogenetically related isolates or species, respectively. PHI test value (Φw) <0.05 indicate significant recombination within the dataset.

Figure 3. Colletotrichum juglandicola (from ex-type CGMCC 3.24312) A, B colonies and reverse after 7 days on PDA medium C, D colonies and reverse after 7 days on MEA medium E conidiomata F, G conidia H conidiophores I, J setae K-N appressoria. Scale bars: 500 μm (E); 10 μm (F-N).