Dendrostoma parasiticum C.M. Tian & N. Jiang

Jiang, Ning, Fan, Xin-Lei, Crous, Pedro W. & Tian, Cheng-Ming, 2019, Species of Dendrostoma (Erythrogloeaceae, Diaporthales) associated with chestnut and oak canker diseases in China, MycoKeys 48, pp. 67-96 : 80-81

Dendrostoma parasiticum C.M. Tian & N. Jiang sp. nov. Figure 8

Diagnosis.

Dendrostoma parasiticum is distinguished from D. quercus by its shorter and narrower conidia.

Holotype.

CHINA. Shaanxi Province: Shangluo City, Zhashui County, Longtougou Village, 33°39'27"N, 109°07'15"E, 2504 m a.s.l., on branches of Quercus wutaishanica , 8 Jul. 2017, N. Jiang (holotype: BJFC-S1570; ex-type culture: CFCC 52762).

Etymology.

Parasiticum, referring to the fungus causing canker diseases on different hosts.

Description.

Sexual morph not observed. Asexual morph: Conidiomata pycnidial, conical to spherical, occurring separately, yellow, semi-immersed in bark, 350-600 μm high, 1000-1800 μm diam.; wall of several layers of bright yellow textura angularis; central column beneath the disc conical, bright yellow. Conidiophores reduced to conidiogenous cells. Conidiogenous cells lining the inner walls of the cavity, hyaline, smooth, subcylindrical to ampulliform, 7-12 × 2-3.5 μm. Conidia hyaline, aseptate, smooth, multiguttulate, thin-walled, fusoid, straight, (9.2 –)9.3–11.7(– 13.6) × (2.7 –)2.8–3.3(– 3.6) μm, l/w = (2.7 –)3–3.9(– 4.2) (n = 50).

Culture characters.

On PDA, cultures are initially white, becoming dark orange after 2 weeks. The colonies are flat with irregular edge; texture uniform, producing concentric circles within 1 month at 25 °C in the dark.

Additional specimens examined.

CHINA. Shaanxi Province: Shangluo City, Zhashui County, chestnut plantation, 33°39'27"N, 109°07'15"E, 2504 m a.s.l., on branches of Castanea mollissima , 8 Jul. 2017, N. Jiang, living culture CFCC 52762 (BJFC-S1569); Shaanxi Province: Ankang City, Xiangxidong Park, 32°40'32"N, 109°18'57"E, 2504 m a.s.l., on branches of Castanea mollissima , 29 Jun. 2017, N. Jiang, living culture CFCC 52763 (BJFC-S1571); Beijing City: Mentougou District, Xiaolongmen Forest Park, 39°17'25"N, 115°45'23"E, 452 m a.s.l., on branches of Castanea mollissima , 17 Aug. 2017, N. Jiang & X.L. Fan, living culture CFCC 52764 (BJFC-S1572); Beijing City: Yanqing District, Yudu Mountain, 40°53'48"N, 115 °54'48"E, 840 m a.s.l., on branches of Quercus aliena , 12 Mar. 2017, N. Jiang, X.L. Fan, Y.M. Liang & C.M. Tian, living culture CFCC 52765 (BJFC-S1573); Hebei Province: Chengde City, chestnut plantation, 40°24'32"N, 117°28'55"E, 262 m a.s.l., on branches of Quercus aliena var. acutiserrata , 15 Oct. 2017, N. Jiang, living culture CFCC 52766 (BJFC-S1574).

Notes.

Dendrostoma parasiticum constitutes a widely distributed species occurring on several Fagaceae tree species including Castanea mollissima , Quercus aliena , Q. aliena var. acuteserrata and Q. wutaishansea . Dendrostoma parasiticum appears to be associated with tree dieback, canker and even tree death, although its pathogenicity remains unproven. Dendrostoma parasiticum is close to D. quercus in the phylogram (Fig. 2), but differs from D. quercus with shorter (9.3-11.7 μm in D. parasiticum vs. 13.3-16.1 μm in D. quercus ) and narrower (2.8-3.3 μm in D. parasiticum vs. 3.5-4.2 μm in D. quercus ) conidia.