Diaporthe grandiflori 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 grandiflori S.T. Huang, J.W. Xia, X.G. Zhang & Z. Li sp. nov. Figure 3

Etymology.

Named after the host Heterostemma grandiflorum on which it was collected.

Diagnosis.

Diaporthe grandiflori can be distinguished from the phylogenetically closely related species D. penetriteum Y.H. Gao & L. Cai in larger α-conidia and β-conidia.

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on infected leaves of Heterostemma grandiflorum . 19 April 2019, S.T. Huang, HSAUP194.84, holotype, ex-holotype living culture SAUCC194.84.

Description.

Asexual morph: Conidiomata pycnidial, subglobose to globose, solitary or aggregated in groups, black, erumpent, coated with white hyphae, thick-walled, exuding golden yellow spiral conidial cirrus from ostiole. Conidiophores hyaline, smooth, septate, branched, densely aggregated, cylindrical, straight to slightly sinuous, 9.5-16.5 × 1.9-2.8 μm. Conidiogenous cells 19.0-22.8 × 1.4-2.4 μm, cylindrical, multi-guttulate, terminal, tapering towards the apex. Alpha conidia abundant in culture, biguttulate, hyaline, smooth, aseptate, ellipsoidal, apex subobtuse, base subtruncate, 6.3-8.3 × 2.8-3.3 µm (mean = 7.5 × 2.9 μm, n = 20). Beta conidia, not numerous, hyaline, aseptate, filiform, slightly curved, tapering towards the apex, 21.5-30.5 × 1.5-2.1 µm (mean = 24.0 × 1.7 μm, n = 20). Gamma conidia not observed. Sexual morph not observed.

Culture characteristics.

Pure culture was isolated by subbing hyphal tips growing from surface sterilized plant material. Colonies on PDA cover the Petri dish after 15 days kept in dark conditions at 25 °C, cottony with abundant aerial mycelium, white on surface side, white to grayish on reverse.

Notes.

Phylogenetic analysis of a combined five loci showed that D. grandiflori (strain SAUCC194.84) formed an independent clade (Fig. 1 ) and is phylogenetically distinct from D. penetriteum . This species can be easily distinguished from D. penetriteum by 87 nucleotides difference concatenated alignment (24 in the ITS region, 1 TUB, 41 CAL and 21 HIS). Morphologically, D. grandiflori differs from D. penetriteum in larger α-conidia (6.3-8.3 × 2.8-3.3 vs. 4.5-5.5 × 1.5-2.5 μm) and longer β-conidia (21.5-30.5 × 1.5-2.1 vs. 16.5-27.5 × 1.0-2.0 μm) ( Gao et al. 2016).

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 3. Diaporthe grandiflori (SAUCC 194.84) a leaf of Heterostemma grandiflorum b, c surface (b) and reverse (c) sides of colony after incubation for 15 days on PDA d conidiomata e conidiophores and conidiogenous cells f alpha conidia g, i alpha conidia and beta conidia h beta conidia. Scale bars: 10 μm (e-i).