Diaporthe chrysalidocarpi 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 chrysalidocarpi S.T. Huang, J.W. Xia, W.X. Sun, & X.G. Zhang sp. nov. Figure 3

Etymology.

Named after the host genus on which it was collected, Chrysalidocarpus lutescens .

Diagnosis.

Diaporthe chrysalidocarpi can be distinguished from the phylogenetically most closely related species D. spinosa by longer beta conidia (28.0-32.5 × 1.2-1.6 vs. 18.5-30.5 × 1.0-1.5 μm), and from other species D. fulvicolor by the types of conidia ( D. chrysalidocarpi produces only beta conidia, while D. fulvicolor produces only alpha conidia) and several loci (25/491 in the ITS region, 18/471 TUB, 4/298 TEF, 28/458 CAL and 13/441 HIS).

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Chrysalidocarpus lutescens ( Palmae ). 19 April 2019, S.T. Huang, HSAUP194.35 holotype, ex-type living culture SAUCC194.35.

Description.

Asexual morph: Leaf spots irregular, pale brown in center, brown to tan at margin. Conidiomata pycnidial, scattered or aggregated, black, erumpent, raising above surface of culture medium, subglobose, exuding white or yellowish creamy conidial droplets from central ostioles after 30 days in light at 25 °C; pycnidial wall consists of black to dark brown, thin-walled cells. Conidiophores 27.5-35.0 × 1.4-2.0 μm, hyaline, slightly branched, swelling at base, subcylindrical, septate, smooth, straight or curved. Conidiogenous cells 10.5-23.0 × 1.4-1.8 μm, phialidic, cylindrical, terminal, straight to sinuous, tapering towards apex. Beta conidia 28.0-32.5 × 1.2-1.6 μm (mean = 30.3 × 1.3 μm, n = 20), filiform, hyaline, straight or slightly curved, aseptate, base subtruncate, tapering towards the base. Alpha conidia and gamma conidia not observed. Sexual morph not observed.

Culture characteristics.

Cultures incubated on PDA at 25 °C in darkness, growth rate 13.3-15.2 mm diam/day, initially white, becoming greyish, reverse pale brown, with concentric rings of dense, sparse hyphae, irregular margin, fluffy aerial mycelium at center, pycnidia forming after 15 days.

Additional specimen examined.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Chrysalidocarpus lutescens ( Palmae ). 19 April 2019, S.T. Huang, HSAUP194.33 paratype; living culture SAUCC194.33.

Notes.

Phylogenetic analysis of a combined five gene showed that D. chrysalidocarpi formed an independent clade (Fig. 1 ) and is phylogenetically distinct from D. spinosa and D. fulvicolor . This species can be distinguished from D. spinosa by 61 different nucleotides in the concatenated alignment (13/492 in the ITS region, 17/471 TUB, 4/298 TEF, 17/458 CAL and 10/441 HIS), and D. fulvicolor by 88 nucleotides (25/491 in the ITS region, 18/471 TUB, 4/298 TEF, 28/458 CAL and 13/441 HIS). Morphologically, D. chrysalidocarpi differs from D. spinosa in having longer beta conidia (28.0-32.5 × 1.2-1.6 vs. 18.5-30.5 × 1.0-1.5 μm) ( Guo et al. 2020). Furthermore, Diaporthe chrysalidocarpi produces only beta conidia, while D. spinosa produces alpha conidia and beta conidia and D. fulvicolor produces only alpha conidia ( Guo et al. 2020). Therefore, we establish this fungus as a novel species.

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 3. Diaporthe chrysalidocarpi (SAUCC 194.35) a diseased leaf of Chrysalidocarpus lutescens b, c surface and reverse of a colony after 15 days on PDA d, e conidiomata f, g conidiophores and conidiogenous cells h, i beta conidia. Scale bars: 10 μm (f-i).