Cytospora shawanensis R. Ma & G. F. Cai, 2024

Cai, Guifang, Zhao, Ying, Zhai, Yawei, Yan, Meilin, Ma, Rong & Zhang, Daoyuan, 2024, Two new species of Cytospora (Diaporthales, Cytosporaceae) causing canker disease of Malus domestica and M. sieversii in Xinjiang, China, MycoKeys 109, pp. 305-318 : 305-318

Cytospora shawanensis R. Ma & G. F. Cai sp. nov.

Fig. 4

Etymology.

Named after the collection site, Shawan.

Descriptions.

Stromata pycnidial, ostiolate, immersed in the host bark, scattered, producing black area on bark, circular to ovoid, with multiple locules. Conceptacle absent. Ectostromatic disc inconspicuous, producing one ostiole per disc when mature. Ostiole in the centre of the disc, black, conspicuous, 60–190 μm diam. Locules numerous, arranged circularly or elliptically with independent walls, 460–1420 μm diam. Conidiophores hyaline, unbranched or branched at the bases. Conidiogenous cells enteroblastic, phialidic, smooth-walled, tapering towards apex. Conidia hyaline, unicellular, smooth-walled, 3.5–5.5 × 1–1.5 µm (av. = 4.3 × 1.2 µm, n = 50).

Cultural characteristics.

Colonies on PDA initially white, covering the petri dish in 3 d, becoming grayish green after 14 d. Conidiomata formed after 5 d, randomly distributed in the colony.

Material examined.

China • Xinjiang Uygur Autonomous, Tacheng City , Shawan County, Daquan Village , 44°20'1.24"N, 85°37'34.40"E, 528 m asl, on dead and dying branches of Malus domestica, Rong Ma , 28 Jul 2015, holotype XJAU-866 , living cultures XJAU 866 = CGMCC 3.18996 ( ITS: PP 965507, act: PP 957865, rpb 2: PP 957872, tef 1: PP 957879, tub 2: PP 957886) ; ibid. XJAU 867 ( ITS: PP 965508, act: PP 957866, rpb 2: PP 957873, tef 1: PP 957880, tub 2: PP 957887) .

Notes.

Cytospora shawanensis is phylogenetically close to C. olivacea in the phylogram (Fig. 2 ). These two species share similar conidial morphology but differs in the sequence data (2 / 502 bp in ITS, 20 / 249 bp in act, 41 / 726 bp in rpb 2 and 39 / 375 bp in tub 2). In addition, host association is helpful for species identification ( C. shawanensis on Malus domestica vs. C. olivacea on Sorbus tianschanica ) ( Pan et al. 2020).

Figures

Figure 2. Phylogenetic tree of Cytospora of ML analysis on basis of combined ITS, act, rpb 2, tef 1 and tub 2 loci. Numbers above the branches indicate ML bootstraps (left, ML BS ≥ 50 %). The tree is rooted with Diaporthe vaccinii (CBS 160.32). New species from the present study are marked in blue.

Figure 4. Morphology of Cytospora shawanensis (XJAU 866) A habitat of conidiomata on the host branch B longitudinal section of the conidioma C transverse section through the conidioma D conidiogenous cells with attached conidia E conidia. Scale bars: 1000 µm (A); 200 µm (B, C); 10 µm (D, E).