Diaporthe melastomatis 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 melastomatis S.T. Huang, J.W. Xia, X.G. Zhang & Z. Li sp. nov. Figure 8

Etymology.

Named after the host Melastoma malabathricum on which it was collected.

Diagnosis.

Diaporthe melastomatis differs from D. parapterocarpi Crous in smaller α-conidia and the types of conidia.

Type.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Melastoma malabathricum . 19 April 2019, S.T. Huang, HSAUP194.55, holotype, ex-holotype living culture, SAUCC194.55.

Description.

Asexual morph: Conidiomata pycnidial, subglobose to globose, black, erumpent, coated with white hyphae, thick-walled, yellowish spiral conidial cirrus exuded from ostioles. Conidiophores hyaline, smooth, septate, branched, densely aggregated, cylindric-clavate, straight to slightly sinuous, tapering towards the apex, 14.5-21.0 × 2.0-3.2 μm. Conidiogenous cells 9.5-13.0 × 1.5-2.5 μm, cylindrical, guttulate, terminal, tapering towards the base. Alpha conidia, hyaline, smooth, aseptate, oblong ellipsoidal, 2-4 guttulate, apex subobtuse, base subtruncate, 5.5-8.5 × 1.7-2.5 µm (mean = 6.8 × 2.1 μm, n = 20). Beta conidia abundant in the culture, hyaline, aseptate, filiform, multi-guttulate, sigmoid to lunate, mostly curved through 90-180°, tapering towards both ends, 25.0-33.5 × 1.1-2.0 µm (mean = 27.6 × 1.4 μm, n = 20). Gamma conidia and sexual morph not observed.

Culture characteristics.

Pure culture was isolated by subbing hyphal tips growing from surface sterilized diseased material. Colonies on PDA cover the Petri diameter after incubation for 15 days in dark conditions at 25 °C, cottony and lobate with abundant aerial mycelium, hyphae white in the margin on surface side, with pale brown concentric ring of dense hyphae on reverse side.

Additional specimens examined.

China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 19 April 2019, S.T. Huang. On diseased leaves of Millettia reticulata , HSAUP194.80 paratype, living culture SAUCC194.80; on infected leaves of Camellia sinensis , HSAUP194.88 paratype, living culture SAUCC194.88.

Notes.

Diaporthe melastomatis is introduced based on the multi-locus phylogenetic analysis, with three isolates clustering separately in a well-supported clade (ML/BI = 100/1). Diaporthe melastomatis is most closely related to D. parapterocarpi , but distinguished based on ITS and TUB loci from D. parapterocarpi by 32 nucleotides difference in the concatenated alignment, in which 20 are distinct in the ITS region, 12 in the TUB region. Morphologically, Diaporthe melastomatis differs from D. parapterocarpi in its smaller alpha conidia (5.5-8.5 × 1.7-2.5 vs. 8.0-10.0 × 2.5-3.0 μm). Furthermore, Diaporthe melastomatis can produce beta conidia, but D. parapterocarpi cannot ( Crous et al. 2014).

Figures

Figure 8. Diaporthe melastomatis (SAUCC 194.55) a branch with leaves of host plant b, c surface (b) and reverse (c) sides of colony after incubation for 15 days on PDA d conidiomata e, f conidiophores and conidiogenous cells g beta conidia h, i, k alpha conidia and beta conidia j alpha conidia. Scale bars: 10 μm (e-k).