Parasitic on living leaves of Musa sp., forming conspicuous, small, rounded, black conidiomata. Sexual morph: undetermined, Asexual morph: Conidiomata 70–140 µm diam., 80–120 µm high, brown to black, pycnidial, amphigenous, usually gregarious, immersed to semi-immersed, globose to depressed globose, unilocular, glabrous, ostiolate. Ostiole circular, excentrical. Conidiomatal wall 10–20 µm wide, composed of thick-walled, dark brown cells of textura angularis in the outer layer, become hyaline cells in the inner layer. Ostiole centrally located, circular, papillate. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3–5 × 3–7 µm, hyaline, enteroblastic, annellidic, lageniform or subcylindrical, indeterminate, smooth-walled, proliferating once or twice. Conidia 7–12 × 5–6.5 µm (= 10 × 6 µm; n = 30), hyaline, ellipsoid, subcylindrical to subglobose with a truncate base, aseptate, thick- and smooth-walled, enclosed in a 1.5–2 µm wide mucoid envelope, with a 10–17 µm long, unbranched, whip-like, apical appendage arising from the apex. Spermatia not observed.
Material examined: Thailand, Chiang Rai, on living leaves of Musa sp., 7 April 2015, Wen-Jing Li, WJL0032 (MFLU 19-2897), (KUN, HKAS 93581).
Notes: The germinating conidia stop growing on PDA. Therefore, the sequence of our collection was obtained directly from conidiomata. Our collection shares a similar habit with P. musarum which is associated with banana freckle disease (Wong et al. 2012). This collection also share similar morphology of conidiomata and conidia with P. musarum, but it was distinguished from the latter [conidia: (12–)13–16(–20)×(7–)9–10(–11)] by its smaller conidia (Wong et al. 2012). The sequences similar between our collection and P. musarum is 98% in LSU (886/904). However, as it lacks suitable genes (e.g., ITS, act, gapdh, tef1), we keep it as Phyllosticta sp.
Phyllosticta sp. (MFUL 19-2897) a Herbarium specimen. b, c Appearance of black conidiomata on the host. d, e Vertical sections of conidiomata. f Vertical section of peridium. g–i Conidiogenous cells and developing conidia. j Germinating conidium. k–o Conidia. Scale bars: b = 500 µm, c = 200 µm, d–e = 100 µm, f, j = 20 µm, g–i, k–o = 10 µm.
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.