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

Fig. 4

Etymology.

Named after Beijing where the fungus was collected.

Description.

Sexual morph not observed. Asexual morph developed on MEA. Conidiomata acervular, yellow, bearing conidial masses. Conidiophores hyaline, smooth-walled, septate and branched. Setae medium to dark brown, smooth to finely verruculose close to the tip, the tip rounded, 1-3 aseptate, 57.2-152.9 μm long. Conidiogenous cells 20-35.6 × 2.8-3.9 μm (mean SD = 26.1 ± 0.9 × 3.0 ± 0.1 μm, n = 20), subcylindrical, straight to curved. Conidia 13.5-20.5 × 3.1-5.9 μm (mean SD = 16.4 ± 1.4 × 4.9 ± 0.5 μm, L/W radio = 3.3, n = 100), hyaline, smooth-walled, subcylindrical, both ends round, 1-3-guttulate, contents granular. Appressoria 5.6-8.4 × 3.9-6.1 μm (mean SD = 6.7 ± 0.2 × 5.1 ± 0.1 μm, L/W radio = 1.3, n = 20), medium to dark brown, variable in shape, often smooth-walled, subglobose, ovate to broadly elliptical in outline.

Asexual morph developed on PDA. Conidia 14.7-22.2 × 4.1-6.3 μm (mean SD = 17.4 ± 1.6 × 5.2 ± 1.6 μm, L/W radio = 3.3, n = 50), hyaline, smooth-walled, subcylindrical, both ends round, 1-3-guttulate, contents granular.

Culture characteristics.

Colonies on MEA, flat, with entire margin, hyaline, 68-78 mm diam. in 7 d. The colonies are round, aerial mycelium white or grey, floccose cottony; surface and reverse grey in the centre and white margin. Myxospores are orange. The colony diameter reached 76-80 mm on PDA. The colonies are round, aerial mycelium white or grey, floccose cottony; surface and reverse grey in the centre and white margin.

Additional specimens examined.

China, Beijing, Changping District, Heishanzhai Village, from leaf of Juglans regia L., 26 Aug 2021, Y. Zhang and L. Zhang (holotype HSY826-18; ex-type living culture, CGMCC3.24308. China, Beijing, Changping District , Heishanzhai Village , from leaf of Juglans regia L., 26 Aug 2021, Y. Zhang and L. Zhang (Paratype HSY826-18): living culture, CGMCC3.24307.

Notes.

Phylogenetic analysis of a concatenated five loci dataset indicated that the clade of Colletotrichum peakense 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). Morphologically, Colletotrichum peakense was distinguishable from C. citrulli by having longer setae and smaller appressoria ( Guo et al. 2022) (Table 2 ), while from C. dimorphum by having longer conidia and longer setae ( Yu et al. 2022) (Table 2 ), from C. gloeosporioides by having longer conidia ( Cannon et al. 2008) (Table 2 ) and from C. nanhuaensis by having longer conidia and shorter appressoria ( Guo et al. 2022) (Table 2 ). The PHI test (Φw = 1.0) detected no significant recombination between related isolates or species-related species (Fig. 2B ).

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 4. Colletotrichum peakense (from ex-type CGMCC 3.24308) 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, I conidiophores J setae K-N appressoria. Scale bars: 500 μm (E); 10 μm (F-N).