Cytospora leucostoma (Pers.) Sacc., Michelia 2: 264 (1881)

Zhu, Haiyan, Pan, Meng, Bezerra, Jadson D. P., Tian, Chengming & Fan, Xinlei, 2020, Discovery of Cytospora species associated with canker disease of tree hosts from Mount Dongling of China, MycoKeys 62, pp. 97-121 : 97

Cytospora leucostoma (Pers.) Sacc., Michelia 2: 264 (1881) Figs 4 , 5

Sphaeria leucostoma Pers., Ann. Bot. 11: 23 (1794)

Valsa leucostoma (Pers.) Fr., Summa Veg. Scand., Section Post. (Stockholm): 411 (1849)

Valsa persoonii Nitschke, Pyrenomyc. Germ. 2: 222 (1870)

Leucostoma persoonii (Nitschke) Höhn., Mitt. Bot. Inst. Tech. Hochsch. Wien 5: 78 (1928)[Additional synonyms in Species Fungorum.]

Description.

Necrotrophic on branches of Betulaceae , Juglandaceae and Rosaceae . Sexual morph: Ascostromata immersed in the bark, erumpent through the surface of bark, scattered, 950-2550 µm in diam., with 8-10 perithecia arranged circularly to irregularly. Conceptacle absent. Ectostromatic disc pale grey, fusoid, 600-2150 µm in diam., with 8-10 ostioles arranged irregularly per disc. Ostioles numerous, dark grey to black, at the same or above the level as the disc, concentrated, arranged irregularly in a disc, 60-120 µm in diam. Perithecia beige with a little black when mature, flask-shaped to spherical, arranged circularly to irregularly, 270-560 µm in diam. Paraphyses large, broad and cylindrical with 1-4 septa, 39-78 × 5.8-8.7 (av. = 50.6 ± 13.7 × 7 ± 0.8, n = 10) μm. Asci free, clavate to elongate obovoid, 35-45 × 6-8 (av. = 40.4 ± 3.3 × 6.9 ± 0.5, n = 10) μm, 8-spored. Ascospores uniseriate to biseriate, elongate-allantoid, thin-walled, hyaline, aseptate, 7-10 × 2-3 (av. = 8.3 ± 0.9 × 2.6 ± 0.2, n = 30) μm. Asexual morph: Conidiomata pycnidial, immersed in the bark, scattered, erumpent through the surface of bark, with multiple locules and a conspicuous central column. Central column beneath the disc more or less conical, brown. Conceptacle absent. Ectostromatic disc buff, discoid, circular to ovoid, 190-310 µm in diam., with 1-2 ostioles per disc. Ostioles grey to black, at the same or above the level as the disc surface, 60-65 μm in diam. Locules numerous, subdivided frequently by invaginations with common walls, circular to ovoid, 700-1000 µm in diam. Conidiophores hyaline, branched at the base or unbranched, approximately cylindrical, 8-14 × 1-2 (av. = 11.5 ± 1.8 × 1.4 ± 0.2, n = 10) µm, sometimes reduced to conidiogenous cells. Conidiogenous cells enteroblastic phialidic, sub-cylindrical to cylindrical, 7-11 × 1-2 (av. = 9 ± 1.4 × 1.5 ± 0.3, n = 10) μm. Conidia hyaline, elongate-allantoid, smooth, aseptate, 4.5-6 × 1-2 (av. = 5.4 ± 0.3 × 1.5 ± 0.2, n = 30) μm.

Culture characteristics.

Cultures initially are white, growing fast up to 8 cm in diam. after 3 days and entirely covering the 9 cm Petri dish after 4 days, becoming greenish-olivaceous after 7-10 days and grey olivaceous after 30 days. In reverse, the cultures are the same as the upper colour after 7 days, becoming olivaceous grey to iron grey after 30 days. Colonies are flat with a uniform texture; sterile.

Habitat and distribution.

Known from several species of Betulaceae , Juglandaceae and Rosaceae around the world.

Materials examined.

China, Beijing City, Mentougou District, Mount Dongling, Xiaolongmen Forestry Centre (115°26'47.36"E, 39°56'06.45"N), from branches of Prunus sibirica , 17 Aug 2017, H.Y. Zhu & X.L. Fan, CF 2019814, living culture CFCC 53140; ibid. CF 2019815, living culture CFCC 53141. China, Beijing City, Mentougou District, Mount Dongling, Xiaolongmen Forestry Centre (115°29'20.52"E, 39°57'47.49"N), from branches of Juglans mandshurica , 17 Aug 2017, H.Y. Zhu & X.L. Fan, CF 2019809, living culture CFCC 53156.

Notes.

Cytospora leucostoma is commonly associated with canker disease of Prunoideae of Rosaceae in China ( Fan et al. 2020). Morphologically, our taxa are similar to previous descriptions of C. leucostoma in having multi-loculate pycnidial stromata with a conspicuous black conceptacle, producing elongate-allantoid, large conidia (4.5-6 × 1-2 μm) ( Teng 1963, Zhuang 2005, Fan et al. 2020). The greenish-yellow of the cultures on PDA medium from Juglans mandshurica is similar to descriptions of those collected from Prunoideae ( Fan et al. 2020). Multigene phylogenetic analyses supported the morphological results with high support values (ML/MP/BI = 100/100/1, Fig. 2 ). By combining morphology and the DNA data, our isolates collected from dead branches of Prunus sibirica and Juglans mandshurica belong to this species. The current study represents a new host record of Juglans mandshurica .

Figures

Figure 2. Phylogram of Cytospora, based on combined ITS, LSU, act, rpb 2, tef 1 - α and tub 2 genes. The MP and ML bootstrap support values above 50 % are shown at the first and second positions, respectively. Thickened branches represent posterior probabilities above 0.95 from the BI. Ex-type strains are in bold. Strains from the current study are in blue.

Figure 4. Cytospora leucostoma (Sexual morph) from Prunus sibirica (CF 2019814). A, B habit of ascomata on twig C transverse section of ascoma D longitudinal section through ascoma E asci and ascospores F ascus G ascospores H colonies on PDA at 3 days (left) and 30 days (right). Scale bars: 1 mm (A); 500 μm (B-D); 10 μm (E-G).

Figure 5. Cytospora leucostoma (Asexual morph) from Juglans mandshurica (CF 2019809). A, B habit of conidiomata on twig C transverse section of conidioma D longitudinal section through conidioma E conidiophores and conidiogenous cells F conidia G colonies on PDA at 3 days (left) and 30 days (right). Scale bars: 1 mm (A); 500 μm (B-D); 10 μm (E, F).