Diaporthe machili S.T. Huang, J.W. Xia, W.X. Sun, & X.G. Zhang, 2021

Huang, Shengting, Xia, Jiwen, Zhang, Xiuguo & Sun, Wenxiu, 2021, Morphological and phylogenetic analyses reveal three new species of Diaporthe from Yunnan, China, MycoKeys 78, pp. 49-77 : 49

Diaporthe machili S.T. Huang, J.W. Xia, W.X. Sun, & X.G. Zhang sp. nov. Figure 5

Etymology.

Named after the host genus on which it was collected, Machilus pingii .

Diagnosis.

Diaporthe machili differs from D. caryae and D. sackstonii in the types of conidia ( D. machili only produces beta conidia, while D. caryae produces alpha conidia and beta conidia, and D. sackstonii only produces alpha conidia), and from D. caryae in longer beta conidia (29.0-39.0 × 1.3-1.5 vs. 15.5-34.0 × 1.1-1.4 μm).

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Machilus pingii ( Lauraceae ). 19 April 2019, S.T. Huang, HSAUP194.111 holotype, ex-holotype living culture SAUCC194.111.

Description.

Asexual morph: Conidiomata pycnidial, aggregated, black, erumpent, subglobose to globose, exuding creamy conidial droplets from central ostioles after 30 days in light at 25 °C. Conidiophores 7.0-11.4 × 1.8-2.8 μm, hyaline, unbranched, densely aggregated, mostly ampulliform, cylindrical, guttulate, septate, straight or slightly curved, swelling at base, tapering towards apex. Beta conidia 29.0-39.0 × 1.3-1.5 μm (mean = 32.5 × 1.4 μm, n = 20), filiform, hyaline, aseptate, mostly curved, J-shaped, swelling in middle, tapering towards both ends. Alpha and gamma conidia not observed. Sexual morph not observed.

Culture characteristics.

Cultures incubated on PDA at 25 °C in darkness, growth rate 16.3-17.5 mm diam/day, aerial mycelium abundant, white on surface, reverse white to pale yellow, with an obvious concentric zonation, pycnidia forming after 15 days.

Additional specimen examined.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Pometia pinnata ( Sapindaceae ). 19 April 2019, S.T. Huang, HSAUP194. 69 paratype; living culture SAUCC194. 69.

Notes.

In the phylogenetic tree, Diaporthe machili forms an independent clade and is phylogenetically distinct from D. caryae and D. sackstonii (Fig. 1 ). Diaporthe machili can be distinguished from D. caryae in ITS, TUB, TEF, CAL and HIS loci by 67 nucleotide differences in concatenated alignment (5/459 in ITS, 10/416 in TUB, 15/334 in TEF, 7/454 in CAL and 30/455 in HIS), and from D. sackstonii in ITS, TUB and TEF loci by 58 nucleotide differences (12/559 in ITS, 23/486 in TUB and 23/348 in TEF). Moreover, Diaporthe machili differs from D. caryae in having longer beta conidia (29.0-39.0 × 1.3-1.5 vs. 15.5-34.0 × 1.1-1.4 μm). Diaporthe machili only produces beta conidia, while D. caryae produces alpha conidia and beta conidia, and D. sackstonii only produces alpha conidia ( Thompson et al. 2015; Yang et al. 2018b).

Figures

Figure 1. Phylogram of Diaporthe spp. based on combined sequence data of ITS, TUB, TEF, CAL and HIS 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. Codes referring to strains from the current study are written in red. Some branches were shortened to fit them to the page as indicated by two diagonal lines with the number of times a branch was shortened indicated.

Figure 5. Diaporthe machili (SAUCC 194.111) a infected leaf of Machilus pingii b, c surface and reverse of colony after 15 days on PDA d, e conidiomata f-h conidiophores and conidiogenous cells i-k beta conidia. Scale bars: 10 μm (f-k).