Phyllosticta savannaensis H.X. Wu & C.L. Gong.

Gong, Cui-Ling, Wu, Hai-Xia, Li, Jin-Chen & Song, Jia-Yu, 2024, Morphological and multi-gene phylogenetic analyses of two new species of Phyllosticta (Phyllostictaceae, Botryosphaeriales) from Southwestern China, Phytotaxa 653 (1), pp. 20-36 : 22-25

Phyllosticta savannaensis H.X. Wu & C.L. Gong. sp. nov. Fig. 2

Fungal Names: FN 571911

Etymology— savannaensis = Savanna, in reference to its special location, Yunnan Yuanjiang Savanna Ecosystem Research Station. Holotype — IFRD 9476

Saprobic on leaf litter. Sexual morph: Black ascomata observed on leaf surface. Ascomata 95–130 μm (x = 109 μm, n = 20) in diameter, semi-buried, globose, black, carbonaceous, releasing ascospores at maturity by dehiscence and forming a central ostiole. Peridium thin, comprising a few layers of angular cells.Asci 40–70 × 10–20 μm (x = 52 × 15 μm, n = 20), 8-spored, bitunicate, clavate to broadly ellipsoid, with a broad, gradually tapering pedicel, with an apical ring and a chamber diameter of 3 μm. Ascospores 12–17 × 5–7 μm (x = 15 × 6 μm, n = 20), ratio of length to width is 2.43:1, biseriate, limoniform with obtuse ends, widest in the centre, hyaline, smooth, and multiguttulate or a large central guttule, occasionally with gelatinous appendages which are more obvious in cotton blue, apical appendage hatshaped, bottom appendage flame-like. Mucilaginous caps not present once released (appendages shown by arrows). Asexual morph: Not observed.

Material examined— CHINA. Yunnan Province: Yuanjiang County, Yuanjiang National Nature Reserve , on dead leaves, 23°28'2"N, 102°10'4"E, 579 m elev., December 2021 (dry season), H.X. Wu, J.C. Li & X.H. Li ( IFRD 9476 , holotype).

Notes: According to phylogenetic tree analysis, P. savannaensis is classified within the P. capitalensis species complex ( Fig. 1 ), which contains 28 species ( Table1 ). The phylogenetic tree reveals that P. savannaensis is most closely related to P. capitalensis , but forms a single branch with strong support (100%/1.00, BS/ BYPP). Morphological characters of P. savannaensis and P. capitalensis exhibit distinct differences, reinforcing the phylogenetic analysis. The size of ascospores and ratio of length to width differed between the two species ( P. capitalensis 11–13 × 3–4 μm, length/width ratio 3.25:1 vs P. savannaensis 12–17 × 5–7 μm, length/width ratio 2.43:1). P. savannaensis ascospores have appendages at both ends, with the apical appendage appearing as a hat and the bottom appendage as a flame, whereas P. capitalensis ascospores are with or without a cap-shaped appendage at the end ( Table2 ). In addition, NCBI blast results of the ITS sequences of P. ovalina (holotype) also give support to our findings. The NCBI blast results of P. savannaensis (holotype) are as follows: P. savannaensis and P. capitalensis , P. fallopiae , P. elongata exhibit only 92.04% sequence identity (query cover = 99%) ( Table 3 ). Based on morphological characters and phylogenetic analysis, P. savannaensis is identified as a new species within the genus Phyllosticta .

Figures

FIGURE 1. Phylogram of Phyllosticta resulting from a maximum likelihood analysis based on a combined matrix of ITS, LSU and TEF1 loci. The tree is artificially rooted to B. obtusa (CMW 8232). ML bootstrap values (left, ML-BS ≥ 50%) and Bayesian posterior probabilities (right, BYPP ≥ 0.9) are given at the nodes. New species of this study are indicated using red font and their associated support is bolded.

FIGURE 2. Phyllosticta savannaensis (IFRD 9476, holotype). a. Microfungi on leaf litter. b–c. Ascomata on leaf surface. d–e. Vertical section of ascomata. f–i. Asci (i in cotton blue). j–n. Ascospores (m, n in cotton blue). Scale bars: b = 1000 μm, c= 500 μm, d = 100 μm, e, g–i = 30 μm, f = 50 μm, j–n = 10 μm.