Podosphaera yulii S.-Y. Liu & P.-L. Qiu 2020
Index Fungorum number: IF556431; Facesoffungi number: FoF 06104
Holotype: CHINA, Jilin Province, Changchun, Jilin Agricultural University, on Crataegus pinnatifida, 1 June 2018, P.L. Qiu (HMJAU91796, holotype).
Morphological description
Mycelium amphigenous, effuse, persistent, often causing yellowish or dark brown discoloration and malformation of the hosts leaves. Hyphal appressoria indistinct nipple-shaped, solitary. Conidiophores arising from the upper surface of hyphal mother cells, (45–)50–105 × 9–12 μm and producing the conidia in chains with clear fibrosin bodies. Foot cells, cylindrical, 22–51(–56) × 7.8–12.7 μm, sometimes slightly swollen at the very base and the basal septum occasionally raising above the junction with the mother cell. Conidia ellipsoid or oval, with distinct fibrosin bodies, 18.6–29.1(–36.5) × 14–21 μm with a length/width ratio of mostly 1.2–2.1. Germ tubes of conidial germination, clavate or somewhat forked, straight or most curved, producing in single, opposite or double at the one end or both ends of the conidia. Chasmothecia 69–93 μm diam, amphigenous, gregarious, including numerous yellowish droplets, and containing one ascus each. Peridium cells of chasmothecia, irregularly polygonal. Appendages, 6–22 per chasmothecium, (41.7–)50–108(–148.4) μm, dark brown at the base, becoming paler towards the apex, apices dichotomously branched, 0.5–1.7 times the chasmothecial and emerging yellowish oil drops after heating in lactic acid.
Habitat: On Crataegus pinnatifida.
Distribution: In China.
GenBank Accession: ITS: MK409979, MK409981, MK409982, MK409980; LSU: MK734073, MK734075, MK734076, MK734074; IGS: MK955881.
Notes: Maximum parsimony phylogenetic analysis based on the ITS sequences demonstrated that Podosphaera yulii formed a single clade with 100% bootstrap support that is distant from P. clandestina, P. curvispora and P. paracurvispora (Fig. 37). The molecular analysis of 28S rDNA sequences suggested the four species clustered with each other but without bootstrap support (Fig. 38). The morphological characteristics and molecular analysis support that the powdery mildew on C. pinnatifida in this study is a new and undescribed species. P. yulii is clearly different from P. clandestina by having mostly curved ascospores, but a few straight, short foot-cells (up to 56 μm in P. yulii vs 35–100(–125) μm in P. clandestina) and more appendages (6–22 per chasmothecium in P. yulii vs 5–15 in P. clandestina). P. paracurvispora and P. curvispora also have curved ascospores. Tang et al. (2017) recorded that P. paracurvispora has foot-cells (13–)20–27(–32) μm in length which is shorter than P. yulii with foot-cells 22–51(–56) μm, and pale brown, curved, crescent-shaped ascospores that differ from P. yulii having curved and colorless ascospores.
Reference: Hai‑Sheng Yuan1,2· Xu Lu1,2 · Yu‑Cheng Dai3 ·
Podosphaera yulii (HMJAU91796, holotype) on Crataegus pinnatifida. a Nipple-shaped hyphal appressoria. b Conidiophore. c Elliptical conidia. d–k Germ tubes of conidial germination. l Chasmothecia. m Peridium cells. n Ascus with 8 curved ascospores. o Ascus after heating. p Ascospore curved and colorless. q Ascospore with yellowish droplet after heating. r Droplet. Scale bars: a–o = 20 μm, p–r = 10 μm.
