Cytospora hebeiensis T. Q. Pei & Y. M. Liang, 2025

Pei, Tingqian, Xiong, Dianguang & Liang, Yingmei, 2025, New species and records of Cytospora (Cytosporaceae, Diaporthales) from tree branches in Hebei Province, China, MycoKeys 126, pp. 187-212 : 187-212

Cytospora hebeiensis T. Q. Pei & Y. M. Liang sp. nov.

Fig. 5

Etymology.

The name refers to Hebei Province, where it was collected.

Description.

Sexual morph: not observed. Asexual morph: Conidiomata Group AII (type a 6), immersed in the bark, scattered, erumpent through the bark surface, circular, with multiple locules. Conceptacle absent. Disc conspicuous, orange to brown, circular to ovoid, 85–105 μm in diameter, with one ostiole per disc. Ostiole in the center of the disc, orange, 50–110 µm in diam. Locules numerous, subdivided frequently with independent walls, 320–820 µm. Conidiophores hyaline, branched at the base or occasionally unbranched, 12–20 × 1–1.5 (av. = 17 ± 2 × 2 ± 0.3, n = 30) µm. Conidiogenous cells enteroblastic, phialidic. Conidia hyaline, elongate-allantoid, smooth, aseptate, 3.6–6.3 × 1.0–1.5 (av. = 4.9 ± 0.4 × 1.2 ± 0.2, n = 50) μm.

Culture characteristics.

Cultures on PDA are initially white, growing fast up to 5 cm after 3 d and entirely covering the 6 cm Petri dish after 4 d. Colony exhibit flat elevation with moderately sparse aerial mycelium.

Materials examined.

China, Hebei Province, Saihanba , 42°23'33"N, 117°22'17"E, from branches of Malus pumila , 8 July 2024, C. M. Tian, T. Q. Pei & Y. Y. Wu ( holotype BJFC -S 2548 , ex-type cultures CFCC 72601 ) .

Notes.

To date, seven Cytospora species have been obtained from Malus pumila (Table 3 ). Cytospora hebeiensis , a novel species isolated from M. pumila in Hebei, China, can be distinguished from C. leucostoma by the absence of a black conceptacle ( Fan et al. 2020). While the other six species also lack a black conceptacle and exhibit overlapping conidial sizes with C. hebeiensis , they are phylogenetically separated into distinct clades. In the phylogenetic tree (Fig. 3 ), C. hebeiensis is most closely related to C. malvicolor (from Corylus mandshurica in Beijing, China) and C. linzhiensis (from Euonymus japonicus and Alnus nepalensis in Xizang, China) ( Lin et al. 2024; Jiang et al. 2025 a). It can be distinguished from C. malvicolor by its smaller conidia (3.6–6.3 × 1.0–1.5 μm vs. 6.5–7.5 × 1.5–2 μm in C. malvicolor ( Lin et al. 2024)) , as well as differences in the following gene regions: ITS (3 / 501 bp), act (3 / 242 bp), rpb 2 (11 / 726 bp), tef 1 - α (21 / 427 bp), and tub 2 (21 / 426 bp). C. hebeiensis differs from C. linzhiensis at ITS (5 / 501 bp), act (4 / 242 bp), rpb 2 (10 / 721 bp), tef 1 - α (29 / 509 bp), and tub 2 (9 / 409 bp), as well as by its narrower conidia (3.6–6.3 × 1.0–1.5 μm vs. 5–6 × 1.5–2 μm in C. linzhiensis ).

Figures

Figure 3. Phylogenetic tree inferred from ML analysis based on combined ITS, act, rpb 2, tef 1 - α, and tub 2 sequence data of the Ribis SC. The tree was rooted with Cytospora donglingensis (CFCC 53159) and C. viticola (CBS 141605). Numbers above the branches indicate MLBP ≥ 75 % and BPP ≥ 0.90. Ex-type isolates are in bold. Isolates in this study are highlighted in two different colors, with the new species shown in orange and the known species shown in green.

Figure 5. Cytospora hebeiensis (BJFC - S 2548). A, B. Habit of conidiomata on branch; C. Transverse section through conidiomata; D. Longitudinal section through conidiomata; E. Conidiophores and conidiogenous cells; F. Conidia. Scale bars: 100 µm (B – D); 10 µm (E, F).