Diaporthe heliconiae S.T. Huang, J.W. Xia, X.G. Zhang & Z. Li, 2021

Sun, Wenxiu, Huang, Shengting, Xia, Jiwen, Zhang, Xiuguo & Li, Zhuang, 2021, Morphological and molecular identification of Diaporthe species in south-western China, with description of eight new species, MycoKeys 77, pp. 65-95 : 65

Diaporthe heliconiae S.T. Huang, J.W. Xia, X.G. Zhang & Z. Li sp. nov. Figure 4

Etymology.

Named after the host Heliconia metallica on which it was collected.

Diagnosis.

Diaporthe heliconiae can be distinguished from the phylogenetically closely related species D. subclavata F. Huang, K.D. Hyde & Hong Y. Li in smaller α-conidia.

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on the symptomatic petiole of Heliconia metallica . 19 April 2019, S.T. Huang, HSAUP194.77, holotype, ex-holotype living culture SAUCC194.77.

Description.

Asexual morph: Conidiomata pycnidial, solitary or aggregated in groups, erumpent, thin-walled, superficial to embedded on PDA, dark brown to black, globose or subglobose, exuding creamy yellowish spiral conidial cirrus from the ostioles. Conidiophores hyaline, aseptate, cylindrical, straight to sinuous, branched, 16.5-25.0 × 1.3-1.8 µm. Alpha conidiogenous cells, cylindric-clavate, terminal, few guttulate, 11.5-18.0 × 1.0-1.5 µm. Beta conidiogenous cells, prismatic, terminal, few guttulate, 10.0-14.1 × 1.0-1.2 µm. Alpha conidia, hyaline, smooth, aseptate, ellipsoidal, 2-4 guttulate, apex subobtuse, base subtruncate, 5.0-6.5 × 2.0-2.5 µm (mean = 6.1 × 2.3 μm, n = 20). Beta conidia hyaline, aseptate, filiform, slightly curved, tapering towards the apex, 25.0-33.5 × 1.0-1.5 µm (mean = 29.4 × 1.3 μm, n = 20). Gamma conidia and sexual morph not observed.

Culture characteristics.

Pure culture was isolated by subbing hyphal tips growing from surface sterilized infected plant material. Colonies on PDA cover the Petri dish diameter after incubation for 15 days in dark conditions at 25 °C. Aerial mycelium abundant, cottony, white, dense in the center, sparse near the margin. White on surface side, white to tanned on reverse side.

Additional specimen examined.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on the symptomatic petiole of Heliconia metallica . 19 April 2019, S.T. Huang, HSAUP194.75 paratype; living culture SAUCC194.75.

Notes.

Diaporthe heliconiae clade comprises strains SAUCC194.75 and SAUCC194.77, closely related to D. subclavata in the combined phylogenetic tree (Fig. 1 ). Diaporthe heliconiae can be distinguished based on ITS, TUB and HIS loci from D. subclavata (16/489 in ITS, 8/357 in TUB and 3/470 in HIS). Morphologically, Diaporthe heliconiae differs from D. subclavata in its smaller α-conidia (5.0-6.5 × 2.0-2.5 vs. 5.5-7.2 × 2.2-2.9 μm). Furthermore, in Diaporthe heliconiae β-conidia were obtained size 25.0-33.5 × 1.0-1.5 µm, while in D. subclavata β-conidia were not obtained ( Huang et al. 2015).

Figures

Figure 1. Phylogram of Diaporthe based on combined 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. Strains from this study are shown in red. Three branches were shortened to fit the page size - these are indicated by symbol (//) with indication number showing how many times they are shortened.

Figure 4. Diaporthe heliconiae (SAUCC 194.77) a petiole of Heliconia metallica b, c surface (b) and reverse (c) sides of colony after incubation for 15 days on PDA d conidiomata on PDA e-g conidiophores and conidiogenous cells h beta conidia i alpha conidia and beta conidia j alpha conidia k alpha conidia and germinating conidia. All in water. Scale bars: 10 μm (e-k).