Nectria nigrescens Cooke, Grevillea

Ma, Rong, Li, Sheng-Nan, Zhao, Ying, Wang, Min, Michailides, Themis J. & Tian, Cheng-Ming, 2020, New species of Nectria and Thyronectria from Xinjiang, China, Phytotaxa 433 (4), pp. 253-264 : 261

Nectria nigrescens Cooke, Grevillea 7: 50, 1878. Fig. 4 .

Host/Distribution:—Twigs of Robinia pseudoacacia , Ulmus sp. , Armeniaca vulgaris , Populus sp. , Juglans regia , Betula sp. , Lycium sp. , Rhus typhina and Morus alba from northwestern China. Known from Acer sp. , Celtis occidentalis in Canada; Betula lutea , Elaeagnus angustifolia , Tilia sp. , Gleditsia triacanthos var. inermis , Ulmus pumila in USA; and Fagus sylvatica in France ( Hirooka et al. 2011, 2012).

Descriptions:—Asexual morph: Stromata erumpent through epidermis, light brown to dark brown. Sporodochial conidiomata with stipe, superficial on well-developed stromata, smooth, scattered, solitary, stipitate, cerebriform or tuberculate, up to 520–790 μm high, 654–1200 μm wide, light brown to dark brown. Hymenium arising directly from textura prismatica, elongating from textura angularis, up to 128 µm long, curved at margin. Conidiophores monoverticillate or rarely biverticillate. Acropleurogenously developing phialides intercalary, occurring below each septum, rarely terminal; intercalary phialides monophialidic, 3.0–5.7 μm long, 1.3–2.0 μm wide at base; conidia hyaline, narrowly long ellipsoidal to cylindrical, straight or slightly curved, non-septate, (4.7–)5.8–7.6(–8.7) × (1.5–)1.8–2.4(–2.9) μm (mean=6.7×2.1 μm, n=80). Sexual state: Undetermined.

Culture characteristics:—Cultures grown on PDA at 25 °C developed white aerial mycelium; however, cultures did not develop concentric circles or produce fruit bodies.

Specimens examined:— CHINA, Xinjiang Uygur Autonomous Region, Ili, Huocheng county , Fushou mountain , 44°24’10.58’’N, 80°43’10.00’’E, elev. 1170 m, on twigs of Robinia pseudoacacia Linn., R. Ma , 13 August 2017 (XJ-FPL 2255, XJAU 2255-4) ; CHINA, Xinjiang Uygur Autonomous Region, Ili, Xinyuan county , 43°22’57.75’’N, 83°36’45.30’’E, elev. 1303 m, on twigs of Populus sp. , R. Ma, 20 August 2017 (XJ-FPL 2759, XJAU 2759-1) ; CHINA, Xinjiang Uygur Autonomous Region, Ili, Xinyuan county , 43°23’05.46’’N, 83°35’52.55’’E, elev. 1273 m, on twigs of Juglans regia Linn., R. Ma , 20 August 2017 (XJ-FPL 2772, XJAU 2772-3) .

Notes:— Nectria nigrescens was first reported by Hirooka et al. (2011, 2012). Strain in this study fit well with the original description of N. nigrescens . Such as sequence comparisons revealed that strains XJAU 2255-4 and XJAU 2772-3 differed from the type specimens (A.R.4266 and A.R.4267) by only 1 bp in the ITS sequence ( Hirooka et al. 2011, 2012). This is the first report of N. nigrescens from Robinia pseudoacacia , Populus sp. and Juglans regia in China.

Figures

FIGURE 4. Morphology of Nectria nigrescens from Juglans regia (XJAU 2772-3). A–B: Sporodochium on natural substrate. C–D: Median section of Sporodochium. E: Conidiophores and conidia. F: Conidia. G: Colonies on PDA after 4 days (left) and 28 days (right). Scale bars:A = 500 μm; B–C = 250 μm; D = 100 μm; E–F = 10 μm.