Cytospora nivea (Hoffm.) Sacc., Michelia

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 : 238-240

Cytospora nivea (Hoffm.) Sacc., Michelia 2: 264 (1881) ( Fig. 7 )

= Sphaeria nivea Hoffm., Veg. Crypt. 1: 28 (1787)

= Valsa nivea (Hoffm.) Fr., Summa veg. Scand., Section Post . (Stockholm): 411 (1849)

= Leucostoma niveum (Hoffm.) Hohn., Mitt. bot. Inst. tech. Hochsch. Wien 5: 58 (1928)

Host and Distribution:—Known from Elaeagnus angustifolia in China; Juniperus and Rosa in Bulgaria; Malus in Iran and South Africa; and Salicaceae in Asia, Europe, North America and South Africa.

Pathogen on twigs and branches of Elaeagnus angustifolia and Salix psammophila . Sexual state:—Stromata immersed in bark. Ascostromata, erumpent through the surface of bark, lenticular, extending to a large circular area, (570–)620– 1080(–1120) μm (average = 930 μm, n = 20) in diameter. Conceptacle dark, surround the ascostromata. Disc white to light brown, nearly flat, circular to ovoid, (170–)200–280(–300) μm (average = 250 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,, (40.6–)42.5–86.1(–89.5) μm (average = 64.8 μm, n = 20) in diameter. Locules dark brown, arranged circularly, flask-shaped to spherical, (160–)210–260(–280) μm (average = 240 μm, n = 20) in diameter. Asci free, clavate to elongate obovoid, (30.1–)31.7–43.5(–44.4) × (5.2–)5.5–7.4(–7.9) μm (average = 39.8 × 6 μm, n = 20), 8-spored. Ascospores biseriate, elongate-allantoid, thin-walled, hyaline, eguttulate, aseptate, (9.7–)10.8–15.3(–16.3) × (1.8–)2.1–3.2(–3.6) μm (average = 13.2 × 2.7 μm, n = 50).

Asexual state:—Stromata immersed in bark. Conidiomata, erumpent through the surface of bark, discoid to conicoid, with multiple locules. Conceptacle dark, surround the stromata. Disc brown to dark grey, nearly flat, ovoid to ellipsoid, (110–) 140–210(–270) μm (average = 190 μm, n=20) in diameter, with one ostiole per disc. Ostiole at the same level as the disc, dark grey to black, (52.5–)54.3–90.9(–93.2) μm (average = 74.8 μm, n = 20) in diameter. Multi-locules arranged irregularly with common walls, (410–)470–650(–770) μm (average = 550 μm, n = 20) in diameter. Conidiophores hyaline, unbranched, or occasionally branched at the bases, (16.9–)18.3–28.5(–29.1) μm (average = 23 μm, n = 20). Conidia hyaline, elongate-allantoid, aseptate, eguttulate, (6–)6.2–9.2(–9.8) × (1.5–)1.7–2.4(–2.9) μm (average = 7.6 × 1.9 μm, n = 50).

mm; b–f, k–m= 0.5 mm; g=20 μm; h=5 μm; n–o=10 μm.

Cultures:—Colony originally white, and producing dark green to black pigment after 7–10 days, flat, felty, with concentric circles, and conidiomata irregular on the medium surface.

Material examined:— CHINA Ningxia Province: Guyuan, Changchengliang , 36°03’01.78” N, 106°16’18.09” E, 1777 m asl., on twigs and branches of Elaeagnus angustifolia , collected by X. L. Fan, 24 Jul 2013 ( BJFC-S964 ) ; living culture, CFCC 89641 ; Shaanxi Province, Yulin, Hongshi Gorge , 38°19’32.43” N, 109°42’00.69” E, 1105 m asl., on twigs and branches of Salix psammophila , collected by X. L. Fan, 29 Jul 2013 ( BJFC-S979 ) ; living culture (from conidia), CFCC 89642 ; ibid., living culture (from ascospore), CFCC 89643 .

Notes: Cytospora nivea is a commonly recorded species associated with Salicaceae hosts, whereas it has only been collected on Populus in China ( Saccardo 1881, 1884; Chen 2002; Zhuang 2005). In the current study, the isolates CFCC 89641, CFCC 89642, and CFCC 89643 were shown to be C. nivea based on phylogenetic analysis and morphological characters ( Adams et al. 2006). This is the first record of this species on Salix psammophila worldwide.

Cytospora nivea has not been epitypified and therefore we treat BJFC-S979 as an authentic specimen. This has proved as consistent results from several other authors without epitypification ( Saccardo 1881, 1884; Zhuang 2005; Adams et al. 2006). It makes sense to epitypify this here for further study. Thus fresh collections of Cytospora nivea are needed for epitypification.

Figures

FIGURE 7. Morphology of Cytospora nivea from Salix psammophila (BJFU-S979). a, d: Habit of conidiomata on twig. b, c: Longitudinal sections through conidiomata. e, f: Transverse sections through conidiomata. g: Conidiophores. h: Conidia. i: Colonies on PDA at 3 days (left) and 30 days (right). j: Habit of ascomata on twig. k: Longitudinal sections through ascomata. l: Disc of ascomata on twig. m: Transverse sections through ascomata. n: Asci. o: ascospores. p: Colonies on PDA at 3 days (left) and 30 days (right). Scale bars: a, j=1