Phyllachora xinpingensis H.X. Wu & J.C. Li., 2023

Li, Jin-Chen, Wu, Hai-Xia & Song, Jia-Yu, 2023, Two new Phyllachora species in Southwest China, Phytotaxa 578 (3), pp. 275-285 : 279-281

Phyllachora xinpingensis H.X. Wu & J.C. Li. sp. nov. Fig. 2

MycoBank: 845539

Etymology— Epithet derived from the type locality.

Holotype — IFRD9465

Parasitic on leaves and stems of Chrysopogon aciculatus (Poaceae) . Sexual morph: Stromata 380–1105 × 190–480 μm (x = 599 × 267 μm, n = 10), fusiform or cymbiform, domed above the leaf surface, amphigenous, scattered, sometimes gregarious, like black nevus, black and carbonaceous. Section of stroma 170–385 μm high, multilocular, peridium composed of brown to dark brown cells of textura angularis. Paraphyses 2–4 μm wide, numerous, persistent, filiform, unbranched, aseptate, many guttules, slightly longer than asci. Asci 70–135 × 11–15 μm (x = 93 × 13 μm, n = 20), thin-walled, 8-spored, persistent, cylindrical to clavate, apex obtuse, with pedicel. Ascospores 14–21 × 7–10 μm (x = 17.3 × 8.3 μm, n = 20), 1-seriate, tear-shaped, rounded at the apex, tapered at the base, hyaline, aseptate, verrucous, with guttules and a mucilaginous sheath. Asexual morph: Not observed.

Material examined— CHINA. Yunnan Province: Xinping County, on stems and leaves of Chrysopogon aciculatus , 101.94°E, 24.05°N, 1525.75 m, 27 October 2021, H . X. Wu & J. C . Li, IFRD9465 , holotype . GenBank accession numbers: LSU: OP359416 ; ITS: OP359398 .

Notes: According to the phylogenetic analysis, P. xinpingensis is closely related to P. arundinellae (= P. oryzopsidis ) ( Fig. 1 ). P. arundinellae , which is a parasite of Arundinella sp. and Oryzopsis sp. was found in Australia, Canada, Japan, North America, Papua, Puerto Rico, South Africa, and Venezuela ( Parbery 1967), while P. xinpingensis is known only on Chrysopogon aciculatus . Morphologically, the asci and ascospores of P. xinpingensis are longer and wider than those of P. arundinellae (asci 70–135 × 11–15 μm vs 70–100 × 7–10 μm, ascospores 14–21 × 7–10 μm vs 10–18 × 5–8.5 μm). The ascospores of P. xinpingensis are tear-shaped, rounded at the apex, tapered at the base, while P. arundinellae is narrowly oval to ovoid. The closest hits using the LSU and ITS sequence had the highest similarity to P. arundinellae isolate MHYAU:108 (GenBank LSU: MG269815 , identities = 809/899 (90 %); ITS: MG269761 , identities = 425/534 (80 %)). Differences in morphological characteristics and host are also supported by the phylogenetic tree, as P. xinpingensis and P. yuanjiangensis cluster independently (100% bootstrap support, 1.00 posterior probabilities) in a branch ( Fig. 1 ).

Five species of Phyllachora have been recorded on Chysopogon spp., namely P. andropogonis-aciculati , P. chrysopogonicola , P. graminis , P. ischaemi , and P. fallax . Morphologically, P. xinpingensis is distinguished by having tear-shaped ascospores. The closest hits using LSU and ITS sequences had the highest similarity to P. chrysopogonicola isolate MFLU 16-2096 (GenBank LSU: MF372146 , identities = 724/901 (80 %); ITS: MF372145 , identities = 321/542 (59 %)) and P. graminis (GenBank ITS: KX451869 , identities = 306/556 (55 %)).

Morphological characteristics of Phyllachora species found in China on Chysopogon spp. are given in Table 2. P . xinpingensis can be distinguished by the size of asci and ascospores, and the shape of ascospores. Therefore, P. xinpingensis is considered a new species of Phyllachora .

Figures

FIGURE 1. Maximum likelihood phylogenetic tree based on three nuclear markers (LSU, ITS, SSU). Support values are ML bootstrap values based on 1000 replicates and posterior probabilities from a Bayesian analysis. Bootstrap values of ML BP> 50% are shown on the left, while values of Bayesian PP> 0.50 are shown on the right. Newly introduced species are in bold and red, followed by the host of the species behind its strain number.

FIGURE 2. Phyllachora xinpingensis (IFRD9465, holotype). a. Black spots on Chrysopogon aciculatus (Poaceae). b, c. Stromata. d. Vertical section of ascomata. e. Paraphyses. f–j. Asci (j in cotton blue). k–p.Ascospores (o in cotton blue, p with gelatinous sheath in ink). Scale bars: b = 1000 μm, c = 500 μm, d = 100 μm, e–j = 20 μm, k–p = 10 μm.