Erysiphe limoniicola Zhao Y. Zhang, S. Y. Liu & T. Z. Liu, 2025

Zhang, Zhao-Yang, Wu, Xue-Lian, Lv, Xiao-Xue, Liu, Tie-Zhi, Jin, Dan-Ni, Liu, Li, Wang, Shuang-Bao, Feng, Jing, Hsiang, Tom, Li, Yu & Liu, Shu-Yan, 2025, Discover hidden taxa of Erysiphe section Erysiphe fungi (Ascomycota, Erysiphaceae) based on morphology and multilocus phylogeny in China, MycoKeys 118, pp. 119-146 : 119-146

Erysiphe limoniicola Zhao Y. Zhang, S. Y. Liu & T. Z. Liu sp. nov.

Fig. 5

Etymology.

Epithet derived from the name of the host genus, Limonium , + cola (dweller).

Diagnosis.

Differs from Erysiphe aurea and E. limonii on hosts of the genus Limonium in the size of the chasmothecia, 69–112 μm diam., the number of asci, (3 –) 4–9, and the number of septa in the appendages, 0–2 (– 4), variably shaped ascospores, and by forming a strongly supported species clade in phylogenetic analyses.

Description.

Mycelium amphigenous, forming dense, thin to thick, persistent patches or complete covers; hyphae 3–6 μm wide, septate, straight or curved, smooth; hyphal appressoria solitary or occasionally in opposite pairs, nipple-shaped or lobed. Asexual morph: Conidiophores arising from superficial hyphal mother cells, erect, straight or curved, 48–103 × (5 –) 6–8 μm (without conidia), foot cells subcylindrical, some distinctly curved at the base, the whole foot cell sometimes wavy-curved, 20–42 × 5–7 μm, the basal septum is mostly elevated, up to 10 µm, followed by 1–3 shorter cells of about the same length or shorter; conidia single, narrowly cylindrical, 21–39 × 10–17 μm; germ tubes near the shoulder, with septa, short to medium in length, showing longitubus pattern, conidial appressoria unlobed but enlarged or curved near the top. Sexual morph: Chasmothecia gregarious, 69–112 μm diam.; peridium cells irregularly polygonal, 4–15 μm diam.; appendages few to many, up to 28, often interwoven with the mycelium, unbranched, mycelium-like, irregularly curved or bent, the appendages are about as long as the chasmothecial diam. or shorter, width uneven, tapering at the tip, which is often obtuse-acuminate, 4–8 µm wide, 0–2 (– 4) - septate, walls thin, smooth to rough, colorless; asci (3 –) 4–9, ellipsoid, ovoid, broadly ovoid, distinctly long-stalked or subsessile, about 47–88 × 30–49 μm; ascospores 3–5, broadly ellipsoid-ovoid, oblong-ovoid, sole-shaped, 17–30 × 8–21 μm.

Holotype.

China, Inner Mongolia Autonomous Region • 1; Xilinhot City ; 43°57'23"n, 116°6'46"e; ca. 1100 m a. s. l.; 28 Sep. 2009; Tie-Zhi Liu & M. Chen leg.; on Limonium bicolor ; CFSZ 1870 . Isotype: same data as for holotype; HMAS 353411 .

Host.

Limonium ( bicolor , aureum and tetragonum ) ( Plumbaginaceae ).

Distribution.

Asia ( China and Japan).

Additional material examined.

China, Inner Mongolia Autonomous Region • 1; Sonid Left Banner ; 43°51'21"n, 113°38'56"e; ca. 1230 m a. s. l.; 11 Sep. 2013; Tie-Zhi Liu leg.; on L. aureum ; CFSZ 6794 .

Notes.

The genus Limonium ( Plumbaginaceae ) comprises approximately 600 globally distributed species ( Koutroumpa et al. 2018). Within this genus, two powdery mildew species have been described: Erysiphe aurea and E. limonii ( Braun and Cook 2012) . E. aurea is known exclusively from its type collection ( HMAS 38952) on L. suffruticosum in Xinjiang, China ( Zheng and Yu 1987). Previous identifications of powdery mildew on L. bicolor and L. aureum from Inner Mongolia ( CFSZ 1870 and 6794) were attributed to E. limonii ( Liu 2010, 2022). Comparative morphological analysis of the examined specimens (with specimens CFSZ 1870 and 6794 borrowed from the Mycological Herbarium of Chifeng College) demonstrated clear differentiation from E. limonii : chasmothecia were significantly smaller (69–112 vs. 90–180 µm), and appendages exhibited fewer septa [0–2 (– 4) vs. 0–7]. Furthermore, the two species exhibit variable ascospore shapes, and are distinct from E. aurea in having septate appendages and lacking the golden-yellow cells of the inner peridial wall.

Phylogenetic analysis of ITS + 28 S rDNA sequences revealed that the Inner Mongolian isolates formed a well-supported clade with Erysiphe sp. on L. tetragonum from Japan ( Meeboon et al. 2021), diverging from E. limonii . Although a single nucleotide difference in the 28 S region was observed, this may reflect geographic or host-associated genetic variation rather than distinct species boundaries. It seems that these two Japanese specimens (= Erysiphe sp. ) pertain to the new species, E. limoniicola . Comparative morphometric analysis further revealed incongruences: while Meeboon et al. (2021) reported conidiophore lengths of 50–127 µm on L. tetragonum , our measurements (48–102 µm) partially overlapped with previous records (64–96 µm) ( Liu 2010, 2022). Such variability in conidiophore length is a common phenomenon in powdery mildew anamorphs, likely often influenced by external influences.

Figures

Figure 5. Symptoms and morphology of Erysiphe limoniicola sp. nov. on Limonium bicolor (holotype: CFSZ 8906) A – C powdery layer and chasmothecia on leaves D, E hyphal appressoria F, G conidiophores H conidium I, J germ tubes K chasmothecium L peridium cells M appendage N asci O, P ascospores. Scale bars: 10 µm (D – J, M, O, P); 20 µm (N); 25 µm (K, L).