Diaporthe rizhaoensis Y.Q. Zhu & Ning Jiang, 2023

Zhu, Ya-Quan, Ma, Chun-Yan, Xue, Han, Piao, Chun-Gen, Li, Yong & Jiang, Ning, 2023, Two new species of Diaporthe (Diaporthaceae, Diaporthales) in China, MycoKeys 95, pp. 209-228 : 209

Diaporthe rizhaoensis Y.Q. Zhu & Ning Jiang sp. nov.

Fig. 3

Etymology.

Named after the collection site of the type specimen, Rizhao City.

Description.

Conidiomata pycnidial, small, scattered, slightly erumpent through bark surface, nearly flat, discoid, with a solitary undivided locule, 150-400 μm diam. Conidiogenous cells 6.7-11.4 × 1.6-3.0 μm, hyaline, unbranched, densely aggregated, mostly ampulliform, guttulate, aseptate, straight or slightly curved, swelling at base, tapering towards apex. Beta conidia 12.9-23.4 × 1.1-2.1 μm (mean = 18.7 × 1.4 μm, n = 50), hyaline, filiform, straight or slightly curved, aseptate, base subtruncate, tapering towards the base. Alpha conidia and gamma conidia not observed. Sexual morph not observed.

Culture characters.

Colonies on potato dextrose agar (PDA) flat, spreading, with flocculent aerial mycelium and entire edge, white, reaching a 90 mm diameter after 14 days at 25 °C; on malt extract agar (MEA) flat, spreading, with flocculent aerial mycelium and crenate edge, white, reaching a 90 mm diameter after 14 days at 25 °C, forming black conidiomata with black conidial masses; on synthetic low nutrient agar (SNA) flat, spreading, with flocculent aerial mycelium forming concentric rings and entire edge, white, reaching a 90 mm diameter after 14 days at 25 °C.

Materials examined.

China, Shandong Province, Rizhao City, Wulian County, Zhongzhi Town , on dead culms of Xanthium strumarium , 5 May 2022, Ning Jiang & Chengbin Wang (holotype CAF 800069; ex-holotype culture CFCC 57562) . Shandong Province, Rizhao City, Wulian County, Xumeng Town , on dead culms of Xanthium strumarium , 5 May 2022, Ning Jiang & Chengbin Wang (cultures CFCC 57563 and CFCC 57564) .

Notes.

Diaporthe rizhaoensis formed a distinct clade with high support (ML/BI = 100/1), and was close to D. guttulata and D. stewartia (Fig. 1 ). Diaporthe rizhaoensis is different from D. stewartia by host association ( D. rizhaoensis on Xanthium strumarium vs. D. stewartia on Cosmos bipinnatus ) ( Harrison 1935; Dissanayake et al. 2020). In addition, D. guttulata and D. stewartia are only known in sexual morph. Moreover, Diaporthe rizhaoensis can be distinguished from D. guttulata (15/364 in cal, 5/428 in his3, 5/313 in tef1, and 1/408 in tub2) and D. stewartii (3/532 in ITS, 7/451 in cal, and 7/369 in tub2) by sequence data. Diaporthe helianthi , D. longicolla , D. pseudolongicolla (= D. novem ) and D. rizhaoensis have been reported form the host Xanthium strumarium ( Vrandecic et al. 2007, 2010; Petrović et al. 2018; Thompson et al. 2018). Morphologically, Diaporthe helianthi is a bit longer than D. rizhaoensis in the beta conidia, but not fully distinguished ( Vrandecic et al. 2007, 2010). Morphology of D. longicolla and D. pseudolongicolla on Xanthium strumarium were not available. However, these four species are phylogenetically distinguished in the phylogram of D. sojae species complex (Fig. 1 ).

Figures

Figure 1. Phylogram of Diaporthe sojae species complex resulting from a maximum likelihood analysis based on a combined matrix of ITS, cal, his 3, tef 1 and tub 2 loci. Numbers above the branches indicate ML bootstrap values (left, ML BS ≥ 50 %) and Bayesian posterior probabilities (right, BPP ≥ 0.9). Isolates from the present study are marked in bold blue.

Figure 3. Morphology of Diaporthe rizhaoensis A colonies on PDA, MEA and SNA at 25 ° C after 2 weeks B habit of conidiomata on the host C transverse section of the conidioma D longitudinal section through the conidioma E-G conidiogenous cells with attached beta conidia H-J beta conidia. Scale bars: 500 µm (B); 100 µm (C, D); 10 µm (E-J).