Diaporthe fraxinicola C.M. Tian & Q. Yang

Yang, Qin, Fan, Xin-Lei, Guarnaccia, Vladimiro & Tian, Cheng-Ming, 2018, High diversity of Diaporthe species associated with dieback diseases in China, with twelve new species described, MycoKeys 39, pp. 97-149 : 97

Diaporthe fraxinicola C.M. Tian & Q. Yang sp. nov. Figure 13

Diagnosis.

Diaporthe fraxinicola can be distinguished from the closely related species D. oraccinii and D. acerigena (described above) based on ITS, tef1 and tub2 loci. Diaporthe fraxinicola differs from D. oraccinii in larger alpha conidia and from D. acerigena in wider alpha conidia.

Holotype.

CHINA. Shaanxi Province: Zhashui city, Niubeiliang Reserve, on symptomatic twigs of Fraxinus chinensis , 7 July 2017, Q. Yang (holotype: BJFC-S1495; ex-type culture: CFCC 52582).

Etymology.

Named after the host genus on which it was collected, Fraxinus .

Description.

Conidiomata pycnidial, immersed in bark, scattered, slightly erumpent through the bark surface, nearly flat, discoid, with a single locule. Ectostromatic disc grey to dark brown, circular to ovoid, one ostiole per disc, 150-325 μm diam. Locule circular, undivided, 275-480 μm diam. Conidiophores 10.5-17.5 × 2.1-3.2 μm, hyaline, branched, cylindrical to clavate, straight, tapering towards the apex. Alpha conidia hyaline, aseptate, ellipsoidal to oval, 2-3-guttulate, rounded at both ends, 7-10 × 2.9-3.2 μm (av. = 8.5 × 3 μm, n = 30). Beta conidia hyaline, filiform, straight or hamate, eguttulate, aseptate, base subtruncate, tapering towards one apex, 19-29.5 × 1.4 µm (av. = 24.5 × 1.4 µm, n = 30).

Culture characters.

Cultures incubated on PDA at 25 °C in darkness. Colony originally flat with white aerial mycelium, becoming yellowish, dense and felted aerial mycelium with age, with visible solitary or aggregated conidiomata at maturity.

Additional material examined.

CHINA. Shaanxi Province: Zhashui city, Niubeiliang Reserve, on symptomatic twigs of Fraxinus chinensis , 7 July 2017, Q. Yang, living culture CFCC 52583 (BJFC-S1496).

Notes.

This new species is introduced as molecular data, shows it to be a distinct clade with high support (ML/BI=100/1) and it appears most closely related to D. oraccinii and D. acerigena . Diaporthe fraxinicola can be distinguished from D. oraccinii by 22 nucleotides in concatenated alignment, in which 6 were distinct in the ITS region, 8 in the tef1 region and 8 in the tub2 region; from D. acerigena by 27 nucleotides in concatenated alignment, in which 11 were distinct in the ITS region, 3 in the tef1 region and 13 in the tub2 region. Morphologically, D. fraxinicola differs from D. oraccinii in longer and larger alpha conidia (7-10 × 2.9-3.2 vs. 5.5-7.5 × 0.5-2 μm); differs from D. acerigena in larger alpha conidia (2.9-3.2 vs. 2.1-2.9 μm) ( Gao et al. 2016).