Cytospora altayensis C. X. Wang, Ning Jiang & R. Ma, 2025

Wang, Caixia, Jiang, Ning, Liu, Chuli, Xu, ZiYan, Lu, Hailong & Ma, Rong, 2025, Morphology and molecular phylogeny reveal new species and records of Diaporthales from Betula in Xinjiang, China, MycoKeys 125, pp. 167-204 : 167-204

Cytospora altayensis C. X. Wang, Ning Jiang & R. Ma sp. nov.

Fig. 8

Etymology.

Named after the collection site of the holotype, Altay Prefecture.

Description.

Conidiomata pycnidial, scattered, immersed to semi-immersed in the bark, discoid to conical, 400–600 μm diam., 250–400 μm high, with an undivided locule. Conceptacle absent. Ectostromatic disc isabelline, circular to ovoid, 150–250 μm diam., with a single ostiole per disc in the centre. Ostiole grey to black, 50–100 μm diam. Conidiophores borne along the locules, hyaline, unbranched or branched at the base, (29 –) 35.5–43.5 (– 47) × 1.5–2 μm. Conidiogenous cells enteroblastic, phialidic, subcylindrical to cylindrical. Conidia hyaline, allantoid, thin-walled, eguttulate, aseptate, smooth, (8.5 –) 9.5–11.5 (– 13) × 2.5–3 (– 3.5) (av. = 10.6 ± 1 × 2.8 ± 0.2, n = 50) μm, L / W ratio = 3.4–4.2.

Culture characteristics.

Colonies on PDA flat, spreading, with moderate aerial mycelium and undulating margin, saffron to ochreous, reaching 90 mm diam. after 2 weeks at 25 ° C, sterile.

Materials examined.

China • Xinjiang Uygur Autonomous Region, Altay Prefecture, Habahe County, Birch Forest Scenic Area , from branches of Betula pendula , 4 October 2024, Rong Ma, Caixia Wang & Hailong Lu ( holotype XJAU 3988 , ex-holotype cultures CFCC 71686 , CFCC 71687 and CFCC 71688 ) .

Notes.

Three isolates of Cytospora from Betula pendula in this study formed a distinct subclade phylogenetically close to Cy. berberidis from Berberis dasystachya , representing a new species (Fig. 4 ). However, Cy. altayensis can be distinguished from Cy. berberidis by conidial size (9.5–11.5 × 2.5–3 μm in Cy. berberidis vs. 6–6.9 × 1.9–2.1 μm in Cy. berberidis ) ( Liu et al. 2015). At the nucleotide level, Cy. altayensis differs from Cy. berberidis ( ITS, 15 / 581; act, 22 / 254; rpb 2, 58 / 721; tef 1, 161 / 597; tub 2, 75 / 415) ( Jeewon and Hyde 2016).

Figures

Figure 4. Maximum Likelihood tree of Cytospora pruinosa species complex generated from combined ITS, act, rpb 2, tef 1 and tub 2 sequence data. Bootstrap support values ≥ 50 % and Bayesian posterior probabilities ≥ 0.90 are demonstrated at the branches. Ex-type strains are marked in bold.

Figure 8. Morphology of Cytospora altayensis from Betula pendula. A, B. Habit of conidiomata on branch; C, D. Transverse section through conidiomata; E. Longitudinal section through conidiomata; F. Conidiophores and conidiogenous cells; G. Conidia. Scale bars: 300 μm (B – E); 10 μm (F, G).