Colletotrichum mengyinense T.C. Mu, J.W. Xia, X.G. Zhang & Z. Li, 2021

Mu, Taichang, Zhang, Zhaoxue, Liu, Rongyu, Liu, Shubin, Li, Zhuang, Zhang, Xiuguo & Xia, Jiwen, 2021, Morphological and molecular phylogenetic analyses reveal three species of Colletotrichum in Shandong province, China, MycoKeys 85, pp. 57-71 : 57

Colletotrichum mengyinense T.C. Mu, J.W. Xia, X.G. Zhang & Z. Li sp. nov.

Figure 3

Etymology.

Named after Mengyin County where the fungus was collected.

Diagnosis.

Colletotrichum mengyinense can be distinguished from the phylogenetically most closely related species C. fructicola (MFLU 090228) by its large conidia (12.5-15.7 × 4.8-6.1 vs. 9.7-14.0 × 3.0-4.3 μm), and five loci (2/509 in the ITS region, 1/139 GAPDH, 9/237 ACT, 8/410 TUB2 and 20/727 GS).

Type.

China, Shandong Province: Mengyin County, on diseased leaves of Rosa chinensis , 25 July 2020, T.C. Mu, holotype HSAUP200702, ex-type living culture SAUCC200702 .

Description.

Leaf spots discoid to irregular, brown or tanned. Asexual morph developed on SNA. A yellowish or orange mass appearing just as accumulations of conidia on the surface of the medium of SNA after 14 days in light at 25 °C. Conidia one-celled, hyaline, smooth-walled, subcylindrical, both ends round, contents granular. Conidia on SNA (12.5-15.7 × 4.8-6.1 µm, mean ± SD = 14.3 ± 1.1 × 5.3 ± 0.4 μm, L/W ratio = 2.7, n = 40). Sexual morph not observed. Conidiogenous cells subcylindrical, hyaline, 5.3-15.5 × 2.9-4.9 μm, opening 1.7-2.5 μm diam. Conidiophores hyaline, smooth walled, septate, branched.

Culture characteristics.

Colonies on PDA flat with entire margin, aerial mycelium white or gray, floccose cottony; surface and reverse gray in the center and grayish margin. PDA attaining 69.3-75.6 mm in diameter after 7 days, at 25 °C, growth rate 9.9-10.8 mm/day. Colonies on SNA sparse hyphae, slow growth.

Additional specimen examined.

China, Shandong Province: Mengyin County, on diseased fruit of Juglans regia , 25 July 2020, T.C. Mu, paratype HSAUP200912, ex-paratype living culture SAUCC200912. China, Shandong Province: Mengyin County, on diseased fruit of Juglans regia , 25 July 2020, T.C. Mu, paratype HSAUP200913, ex-paratype living culture SAUCC200913. China, Shandong Province: Mengyin County, on diseased fruit of Juglans regia , 25 July 2020, T.C. Mu, paratype HSAUP200983, ex-paratype living culture SAUCC200983.

Notes.

Phylogenetic analysis of a combined seven gene showed that Colletotrichum mengyinense formed an independent clade (Fig. 1 ) and is phylogenetically distinct from C. fructicola ( Prihastuti et al. 2009). This species can be distinguished from C. fructicola by 40 different nucleotides (2/509 in the ITS region, 1/139 in the GAPDH region, 9/237 ACT, 8/410 TUB2 and 20/727 GS). What’s more, C. mengyinense differs from C. fructicola in having large conidia (12.5-15.7 × 4.8-6.1 vs. 9.7-14.0 × 3.0-4.3 μm, mean: 14.3 × 5.3 vs. 11.53 × 3.55 μm). Therefore, we establish this fungus as a novel species.

Figures

Figure 1. Phylogram of Colletotrichum gloeosporioides complex based on combined ITS, GAPDH, CHS- 1, ACT, TUB 2, CAL and GS genes. The ML and BI bootstrap support values above 50 % and 0.90 BYPP are shown at the first and second position, respectively. Strains marked with " * " are ex-type or ex-epitype. Strains from this study are shown in red. Two branches were shortened to fit the page size-these are indicated by the symbol (//) with an indication number showing how many times they are shortened.

Figure 3. Colletotrichum mengyinense (SAUCC 200702) a branch with leaves of host plant b, c surface (b) and reverse (c) sides of colony after incubation for 7 days on PDA d conidiomata e-g conidiophores, conidiogenous cells and conidia h-j conidia. Scale bars: 10 μm (e-j).