Gnomoniopsis chinensis C.M. Tian & N. Jiang, 2020

Jiang, Ning, Liang, Ling-Yu & Tian, Cheng-Ming, 2020, Gnomoniopsis chinensis (Gnomoniaceae, Diaporthales), a new fungus causing canker of Chinese chestnut in Hebei Province, China, MycoKeys 67, pp. 19-32 : 19

Gnomoniopsis chinensis C.M. Tian & N. Jiang sp. nov. Figures 3 , 4

Etymology.

Named after the country where it was first collected.

Description.

Pathogenic on stems and branches of Castanea mollissima . Conidiomata pseudostromatic, globose to pulvinate, occurring separately, yellow to orange, semi-immersed in bark, 400-1000 µm high, 500-1500 µm diam, unilocular, single ostiolate, forming long, wide orange tendrils, 1500-2000 µm × 400-500 µm. Conidiophores indistinct, often reduced to conidiogenous cells. Conidiogenous cells oval, hyaline, 1-celled, 6-12 µm. Conidia oval, oblate, fusiform, straight to curved, hyaline, 2-3 guttules, (6.0-)6.5-8.5(-9.0) × (2.2-)2.7-3(-3.5) µm (mean = 7.5 × 2.7 µm).

Culture characters.

Colonies on PDA attaining 90 mm after 20 days at 25 °C, flat, velutinous to shortly woolly, dark brown in center, gradually lightening to pale grey at margin; margin diffuse; reverse of almost same colors as surface.

Specimens examined.

China, Hebei Province, Chengde City, chestnut plantation, 40°24'32.16"N, 117°28'56.24"E, 262 m asl, on stems and branches of Castanea mollissima , Ning Jiang, 11 October 2017 (BJFC-S1380, holotype; ex-type culture, CFCC 52286). Hebei Province, Qinhuangdao City, chestnut plantation, 40°22'52.32"N, 119°11'52.18"E, 246 m asl, on branches and twigs of Castanea mollissima , Ning Jiang, 14 October 2017 (BJFC-S1382, paratype; living culture, CFCC 52288). Hebei Province, Tangshan City, chestnut plantation, 40°12'59.76"N, 117°59'7.24"E, 67 m asl, on stems and branches of Castanea mollissima , Ning Jiang, 18 October 2017 (BJFC-S1383; living culture, CFCC 52289).

Notes.

Three Gnomoniopsis species have been discovered from the host genus Castanea . They share similar conidial dimension (6.0-9.0 × 2.2-3.5 µm in Gnomoniopsis chinensis vs. 5.0-8.0 × 2.0-3.5 µm in G. daii vs. 6.0-9.5 × 2.0-4.0 µm in G. smithogilvyi ) ( Crous et al. 2012; Jiang and Tian 2019). However, we can distinguish them easily by the phylogram of ITS, tef1 and tub2 (Fig. 2 ). In addition, Gnomoniopsis chinensis and G. daii inhabit the Chinese chestnut ( Castanea mollissima ), but G. smithogilvyi on the European chestnut ( C. sativa ) and C. crenata × C. sativa hybrids.

Figures

Figure 2. Consensus tree resulting from a RAxML analysis of combined ITS, tef 1 and tub 2 sequence alignment for species of Gnomoniopsis. The scale bar represents the expected number of changes per site.

Figure 3. Conidiomata of Gnomoniopsis chinensis from Castanea mollissima (BJFC-S 1380, holotype) a-c habit of conidiomata on the chestnut stem d transverse sections through conidiomata e longitudinal sections through conidiomata. Scale bars: 1 mm (b-e).

Figure 4. Morphology of Gnomoniopsis chinensis from PDA (CFCC 52286, ex-type culture) a colonies on PDA b conidiomata formed on PDA c, f conidia d, e conidiogenous cells. Scale bars: 1 mm (b); 10 μm (c-f).