Diaporthe heterostemmatis 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 heterostemmatis S.T. Huang, J.W. Xia, X.G. Zhang & Z. Li sp. nov. Figure 5

Etymology.

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

Diagnosis.

Diaporthe heterostemmatis differs from its closest phylogenetic species D. subellipicola S.K. Huang & K.D. Hyde in ITS, TUB and TEF loci based on the alignments deposited in Tree-BASE.

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on infected leaves of Heterostemma grandiflorum . 19 April 2019, S.T. Huang, HSAUP194.85, holotype, ex-holotype living culture SAUCC194.85.

Description.

Asexual morph: Conidiomata pycnidial, 3-5 pycnidia grouped together, globose, black, erumpent, exuding creamy to yellowish conidial droplets from ostioles. Conidiophores hyaline, septate, branched, elliptical or cylindrical, straight to sinuous, 6.5-10.5 × 2.5-4.5 μm. Conidiogenous cells 5.3-11.8 × 1.5-3.2 μm, phialidic, cylindrical, enlarged towards the base, tapering towards the apex, slightly curved, neck up to 5.5 μm long, 2.0 μm wide. Alpha conidia, hyaline, smooth, aseptate, ellipsoidal, biguttulate, apex subobtuse, base subtruncate, 5.8-7.5 × 2.5-3.3 µm (mean = 6.5 × 3.0 μm, n = 20). Beta conidia hyaline, aseptate, filiform, few guttulate, hooked and mostly curved through 90-180°, tapering towards both ends, 16.0-22.7 × 1.0-1.5 µm (mean = 20.4 × 1.2 μm, n = 20). Gamma conidia and 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 diameter after incubation for 15 days in dark conditions at 25 °C. Aerial mycelium white, cottony, feathery, with concentric zonation, white on surface side, pale brown to black on reverse side.

Additional specimen examined.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on infected leaves of Camellia sinensis . 19 April 2019, S.T. Huang, HSAUP194.102 paratype; living culture SAUCC194.102.

Notes.

This new species is proposed as the molecular data showed it forms a distinct clade with high support (ML/BI=98/1) and it appears most closely related to D. subellipicola . Diaporthe heterostemmatis can be distinguished from D. subellipicola by 57 nucleotides in concatenated alignment, in which 8 were distinct in the ITS region, 28 in the TUB region and 21 in the TEF region. Morphologically, D. subellipicola was observed only on the basis of the sexual morph and culture characteristics ( Hyde et al. 2018).

Figures

Figure 5. Diaporthe heterostemmatis (SAUCC 194.85) a leaf of host plant b, c surface (b) and reverse (c) sides of colony, after incubation for 15 days on PDA d conidiomata on PDA e, f conidiophores and conidiogenous cells g beta conidia h Alpha conidia i, j alpha conidia and beta conidia. Scale bars: 10 μm (e-j).