Cytospora populina (Fuckel) C.M. Tian, X.L. Fan & K.D. Hyde, 2015

Fan, Xin-Lei, Hyde, Kevin D., Yang, Qin, Liang, Ying-Mei, Ma, Rong & Tian, Cheng-Ming, 2015, Cytospora species associated with canker disease of three anti-desertification plants in northwestern China, Phytotaxa 197 (4), pp. 227-244 : 234-235

Cytospora populina (Fuckel) C.M. Tian, X.L. Fan & K.D. Hyde , comb. nov. ( Fig. 4 )

MycoBank MB 809224, Facesoffungi number: FOF00308.

Basionym:— Valsa populina Fuckel, Jb. nassau. Ver. Naturk. 25–26:314 (1871)

Host and Distribution:—Known from Alnus inokumai and Pseudotsuga taxifolia in Japan; and Salicaceae in China, Europe and Japan.

Pathogen on twigs and branches of Salix psammophila . Sexual state:—Stromata immersed in bark. Ascostromata, erumpent through the surface of bark, lenticular, extending to a large circular area, (900–)950–1130(–1210) μm (average = 1010 μm, n = 20) in diameter. Conceptacle absent. Disc light grey to black, nearly flat, circular to ovoid, (100–)110–160(–180) μm (average = 140 μm, n = 20) in diameter. Ostioles numerous, dark brown to black, at the same level as the disc, occasionally area below disc a lighter entostroma, (33.1–)33.8–47.6(–48.3) μm (average = 42.4 μm, n = 20) in diameter. Locules dark brown, arranged circularly, flask-shaped to spherical, (220–)240–330(–370) μm (average = 280 μm, n = 20) in diameter. Asci free, clavate to elongate obovoid, (51.5–)54.7–64.4(–66.9) × (7.5–)8.1– 13(–14.2) μm (average = 61.5 × 11.1 μm, n = 20), 4-spored. Ascospores biseriate, elongate-allantoid, thin-walled, hyaline, lacking guttules, aseptate, (17.5–)18.9–24.3(–25.1) × (4–)4.4–5.8(–6.4) μm (average = 21 × 5.2 μm, n = 50).

Cultures/Asexual state:—Colony white, flat, felty, texture uniform, conidiomata sparse, irregularly distributed.

Material examined:— CHINA Shaanxi Province: Yulin, Hongshi Gorge , 38°19’40.83” N, 109°42’37.98” E, 1092 m asl., on twigs and branches of Salix psammophila , collected by X. L. Fan, 29 July 2013 ( BJFC-S978 ) ; living culture, CFCC 89644 .

Notes: Cytospora populina (= Valsa populina ) is a species responsible for poplar canker. It differs from other Cytospora species as asci have four ascospores; the asexual state is unknown. The definition of this species has always been confused. Kobayashi (1969) regarded it as the synonym of V. salicina Fr. and described it with “4 ascospores”. However, the original description from Saccardo (1882) distinguished Valsa salicina and Cytospora populina with eight ascospores and four ascospores, respectively. Species Fungorum (http://www.speciesfungorum.org/) list Naemaspora populina Pers. , as the possible asexual state of Valsa populina cited by Fuckel (1871), as a synonym of Cytospora ambiens , although the latter species also had eight ascospores. Sogonov et al. (2008) regarded Valsa populina as a synonym of Plagiostoma salicellum Sogonov , and described it as “ascospores one-septate, ellipsoid to fusiform”. This is inconsistent with the original Latin description of V. populina . In the current study, isolate CFCC 89644 was shown to be Valsa populina based on previous described morphological characters, host, and distribution ( Saccardo 1882, Tai 1979). The species was first recorded on Salix psammophila worldwide and treated as a novel combination.

Cytospora populina has not been epitypified and therefore we treat BJFC-S978 as an authentic specimen. This has been proved as consistent results from several other authors without epitypification ( Saccardo 1882; Kobayashi 1969; Tai 1979). It makes sense to epitypify this here for further study. Thus fresh collections of Cytospora populina are needed for epitypification.

Figures

FIGURE 4. Morphology of Cytospora populina fromSalix psammophila (BJFC-S978).a, d:Habit of ascomata on atwig.b, c: Longitudinal sections through ascomata. e, f: Transverse sections through ascomata. g: Ascus. h: ascospores. i: Colonies on PDA at 3 days (left) and 30 days (right). Scale bars: a=1 mm; b–f=0.5 mm; g–h=20 μm.