Diplodia populicola Z. Zhang & Y. Zhang, 2025

Zhang, Zhe, Jiao, Ning, Guo, Lin-Na, Wang, Jia-Wen & Zhang, Ying, 2025, Diplodia populicola sp. nov. causing branch canker of poplar in Beijing, China, Phytotaxa 711 (3), pp. 293-300 : 297

Diplodia populicola Z. Zhang & Y. Zhang sp. nov. ( FIGURE 2 )

MycoBank: MB859461

Etymology: Named from “ Populus ”, in reference to the host genus.

Description: Infected branches nearly circular, blister-like lesions around the lenticels in the early stage. Subsequently, the lesions dehydrate and shrivel, forming circular, slightly sunken, dark brown necrotic spots. The sexual morph was not observed. Conidiomata pycnidial globose, stromatic, immersed, sometimes superficial, solitary or aggregated, dark brown to black. Conidiogenous cells hyaline, thin-walled, smooth, cylindrical, swollen at the base, discrete, and produce a single conidium at the tip ( FIGURE 2 ). Conidia oblong, clavate to elliptical, with a blunt apex and a thick, smooth wall, aseptate, 20.9– 23.5 μm × 8–10.5 μm (mean SD = 22.4 ± 0.7 × 8.9 ± 0.8 μm, n = 30, L/W = 2.4) in size, appearing hyaline to yellowish, became dark brown when released ( FIGURE 2 ).

Culture characteristics: The average diameters of colonies on PDA were 85 mm, respectively, after three days of dark incubation at 24 °C. The mycelium developed circular colonies, initially white and cotton-like. After a seven-day incubation period at 24°C, the colonies turned black, with some hyphae becoming aerial ( FIGURE 2 ).

Material examined: CHINA, Beijing, Changping District, Wenyuhe Park (40°07’33.9”N, 116°22’17.5”E), from branches of poplar, 23 September 2023, Z. Zhang , N. Jiao and Y. Zhang (holotype WYHD7-1 ; ex-type living culture CGMCC 3.28774 ). CHINA, Beijing, Changping District , Wenyuhe Park (40°07’33.9”N, 116°22’17.5”E), from branches of poplar, 23 September 2023, Z. Zhang, N. Jiao and Y. Zhang (paratype WYHD7-2 ; living culture CGMCC 3.28775 ) .

Notes: A combination of morphological characteristics and multi-gene phylogenetic analyses based on ITS, tef1- α, and tub2 loci provided evidence for its classification. Phylogenetic analysis demonstrated that D. populicola formed a distinct lineage clustering with D. seriata and its close relatives, yet with a clearly separate branch, supporting its designation as a novel species. The tef1-α marker is regarded as one of the most informative for distinguishing species within the Botryosphaeriaceae . Morphologically, D. populicola resembles its close relative D. seriata ( Phillips et al. 2013) , but has smaller conidia (20.9–23.5 × 8–10.5 vs. 21.5–28 × 11–15.5 μm) and exhibits a higher length-to-width ratio compared to D. seriata ( L / W = 2.4 vs. 1.9).

Figures

FIGURE 2. Cultural and morphological characteristics of Diplodia populicola. A, B, front and reverse view of the colony on PDA; C, pycnidia on pine needle; D, E, conidiogenous cells with immature conidia; F, G, released conidia. Scale bars: C= 500 μm; D, E, F, G = 10 μm.