Cytospora pseudochrysosperma L. Lin & X. L. Fan

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 pseudochrysosperma L. Lin & X. L. Fan , Studies in Mycology 109: 372 (2024)

Fig. 6

Description.

Sexual morph: Stromata Group SII, immersed in the bark, erumpent through the surface, extending to a large circular area, with 12–18 irregularly arranged perithecia. Conceptacle absent. Disc light grey to black, surrounded by ostioles, with an orange center, circular to ovoid, 123–173 µm in diam. Ostioles umber to black when mature, arranged irregularly in a disc, flask-shaped to spherical, 163–244 µm. Asci hyaline, with a chitinoid, refractive ring, clavate to elongate-obovoid, 33.5–53.2 × 7.1–10.7 (av. = 46.4 ± 1.9 × 9.4 ± 0.7, n = 30) µm, 8 - spored. Ascospores hyaline, elongate-allantoid, thin-walled, aseptate, 9.3–11.8 × 1.8–2.7 (av. = 9.9 ± 0.4 × 2.2 ± 0.1, n = 50) µm. Asexual morph: not observed.

Culture characteristics.

Cultures on PDA are white, growing fast, entirely covering the 6 cm Petri dish after 2 d, flat, retained original coloration after 30 d.

Materials examined.

China, Hebei Province, Saihanba , 42°23'33"N, 117°22'17"E, from branches of Salix matsudana , 8 July 2024, C. M. Tian, T. Q. Pei & Y. Y. Wu ( BJFC -S 2552 , living culture CFCC 72613 ; BJFC -S 2553 , living culture CFCC 72617 ) .

Notes.

Cytospora pseudochrysosperma was initially regarded as C. chrysosperma based on irregularly arranged perithecia and was confirmed to be a pathogen of poplar and willow canker disease in China ( Tai 1979; Wei 1979; Zhuang 2005). Based on the phylogenetic discovery that this species resides in a clade distinct from the epitype of C. chrysosperma, Lin et al. (2024) established it as a new species. Jiang et al. (2025 a) reported that it infects a wide range of hosts, including Betula utilis , Populus sp. , and Sorbus rehderiana ; notably, it is frequently isolated from various Salix spp. , such as S. takasagoalpina , S. caprea , S. integra , and S. chaenomeloides . Although in the tub 2 single-gene phylogeny the sequences of C. pseudochrysosperma did not form a monophyletic clade (see S 1), this is likely attributed to intraspecific genetic variation potentially driven by geographical differences. Crucially, in the multi-locus phylogenetic analysis, all C. pseudochrysosperma isolates, including strains CFCC 72613 and CFCC 72617 obtained from S. matsudana in this study, clustered together with a highly supported clade ( MLBP / BPP = 97 / 1.00). This robust phylogenetic placement, coupled with congruent morphological characteristics, confirms their identification as C. pseudochrysosperma and extends the known host range to S. matsudana . This expands its previously documented locations in Gansu and Xizang to the new province, Hebei.

Figures

Figure 6. Cytospora pseudochrysosperma (BJFC - S 2553). A, B. Habit of pseudostroma on branch; C. Transverse section through pseudostroma with ascomata; D. Longitudinal section through pseudostroma with ascomata; E, F. Asci; G. Ascospores. Scale bars: 100 μm (B – D); 10 μm (E – G).