Erysiphe deutziicola P.-L. Qiu, S.-Y. Liu & Y. Li

Qiu, Peng-Lei, Braun, Uwe, Li, Yu & Liu, Shu-Yan, 2019, Erysiphedeutziicola sp. nov. (Erysiphaceae, Ascomycota), a powdery mildew species found on Deutziaparviflora (Hydrangeaceae) with unusual appendages, MycoKeys 51, pp. 97-106 : 100

Erysiphe deutziicola P.-L. Qiu, S.-Y. Liu & Y. Li sp. nov. Figure 2

Etymology.

Named after the host genus, Deutzia , + -icola (dweller).

Diagnosis.

Differs from all known Erysiphe species on hosts belonging to the Hydrangeaceae in having very long conidiophores, up to 235.0 µm and chasmothecia with mycelioid appendages, circinate at the apex.

Type.

CHINA. Beijing City, Baihua Mountain, on leaves of Deutzia parviflora , 19 October 2018, P.-L. Qiu, S.-R. Tang & L. Liu, HMJAU-PM91860 (holotype) and HMAS 248089 (isotype) in the Herbarium Mycologicum Academiae Sinica (HMAS), Beijing; ibid., on leaves of D. parviflora , 26 May 2018, P.-L. Qiu, S.-R. Tang & D.-N. Jin, HMJAU-PM91861 (paratype).

Description.

Forming distinct white colonies, very small and dense, covering both sides of the leaves, causing discolourations of entire leaves or even malformations. Mycelium amphigenous, effuse and persistent. Hyphal appressoria distinctly lobed, solitary (Figure 2, A). Conidiophores, short to very long, 54.5‒171.0(‒235) × 5.8‒8.0 μm, arising from the upper surface of hyphal mother cells (Figure 2, B‒D). Foot-cells straight, (23‒)30.5‒75.0 × 5.7‒7.7 μm, followed by 1 to 3(‒4) cells, 13‒80 μm in length. Conidia formed singly, hyaline, ellipsoid-ovoid or oblong, 18.6‒35.5 × 10‒14 μm with a length/width ratio varying from 1.4‒3.0(‒3.3) (Figure 2, E‒G). Germ tubes on the conidia with lobed apex or longitubus pattern, apex simple or somewhat swollen, produced laterally, near the middle or in perihilar position (Figure 2, H‒J). Chasmothecia, amphigenous, scattered, 70‒100.0 μm diam. (Figure 2, K). Peridium cells irregularly polygonal, 3.5-12.5 µm diam. (Figure 2, M). Appendages 6‒14 per chasmothecium, mycelioid, hyaline, aseptate, extremely long and flexuous, 1.3‒7.0 times as long as the chasmothecial diameter, up to 600 μm, 3-9 µm wide in the lower half, apices mostly sinuous-geniculate or branched, circinate at the near apex, coils relatively loose and wide (Figure 2, L). Asci 4-6 per chasmothecium, broad obovoid-saccate or clavate, short-stalked or sessile, 48‒71.5 × 28.5‒49.5 μm (Figure 2, N‒R). Ascospores ovoid or ellipsoid, 5‒8 in each ascus, 13.0‒20.5 × 10.5‒14.5 μm (Figure 2, S‒T).

Host range and distribution.

On Deutzia parviflora ( Hydrangeaceae ) in Beijing, China.