Phyllachora cephalostachyi X.L. Li, 2021

Li, Xiao-Ling, Yu, Hai-Ying, Luo, Xi, Wu, Hao, Zhao, Chun-Yan, Promputtha, Itthayakorn & Sun, Da-Feng, 2021, Phylogeny of Phyllachora species on bamboo and P. cephalostachyi sp. nov. from China, Phytotaxa 514 (2), pp. 158-166 : 162-163

Phyllachora cephalostachyi X.L. Li , sp. nov. ( Fig. 2 ) MycoBank number: MB 831343

Type:— CHINA. Yunnan Province: Xishuangbanna, Mengla, Xishuangbanna Tropical Botanical Garden , Chinese Academy of Sciences, on Cephalostachyum pergracile , 20 Oct. 2018, X.L. Li ( MHYAU 223 , holotype) .

Etymology:— Named after the host genus Cephalostachyum from which the type species was collected.

On living leaves of Cephalostachyum pergracile (Bambusoideae) . Tar spots 1–2 × 0.5–2 mm, more prominent on the upper leaf surface, circular or ellipsoid, black, shiny, solitary or gregarious, moderately raised, with a yellow halo of discoloured host tissue. Sexual morph Ascomata 130–200 μm high, 80–200 μm diam. (x = 160 × 130 μm, n = 10), immersed in the leaf tissue, occupying the entire leaf thickness, often developing next to adjacent ascomata and confined by host vascular tissue, suboblate to subglobose, sometimes irregular in shape. Paraphyses numerous, hyaline, filiform, unbranched, septate, not constricted at septa, longer than asci, tapering apices, arise from the inner basal and lateral walls. Asci 122–193 × 10–23 μm (x = 150 × 12 μm, n = 30), 8-spored, unitunicate, cylindrical or clavate, short pedicellate, apex obtuse. Ascospores 14–25 × 6–11 μm (x = 22 × 9 μm, n = 30), uniseriate, often biseriate and overlapping, hyaline, dump-bell shape (with constrictions at the centre) and ellipsoidal, some ovoid, with acute ends, one-celled, some with one large fat globule in the centre, with a mucilaginous sheath. Asexual morph Undetermined.

Notes: — Phyllachora cephalostachyi is the first Phyllachora species reported on the genus Cephalostachyum . This is an interesting finding as the fungus was collected from an endemic species of bamboo, Cephalostachyum pergracile , from Xishuangbanna Tropical Botanical Garden.

Phyllachora cephalostachyi is characterized by the presence of dumb-bell and ellipsoidal or ovoid ascospores with acute poles. There are 33 Phyllachora species reported on bamboo in the world ( Table 2 ). Compared with the morphological characteristics of those known species from bamboo, P. cephalostachyi is most similar to P. dendrocalami-membranacei . Both species share cylindrical asci and dumb-bell, ellipsoidal, or ovoid ascospores, and overlap in ascus and ascospore size. Type collections of both P. cephalostachyi and P. dendrocalami-membranacei were found in Xishuangbanna Tropical Botanical Garden, Mengla. However, the phylogenetic analysis confirmed that P. cephalostachyi and P. dendrocalami-membranacei are two distinct species. Morphological comparison between P. cephalostachyi and related species from bamboo are provided in Table 2 .

Figures

FIGURE 2. Phyllachora cephalostachyi (MHYAU 223, holotype). a, b. Tar spots on the leaf surface. c. Cross section of ascoma. d. Developing ascus. e–g. Asci. h, i. Ascospores. Scale bars: c–i = 20 μm.