Phyllosticta sphaeropsoidea Ellis & Everh., Bull. Torrey bot. Club 10(9):  (1883)
Facesoffungi number: FoF 07509
Parasitic on leaves of Aesculus hippocastanum (Sapindaceae). Sexual morph: undetermined. Asexual morph: Conidiomata 80–100 diam., 90–130 µm high, pale brown to brown, pycnidial, amphigenous, predominantly epiphyllous, solitary to gregarious or confluent, subepidermal, initially immersed, ultimately becoming erumpent, globose, unilocular, glabrous, thick-walled, ostiolate. Ostiole single, circular, centrical. Conidiomatal wall 6–30 µm wide, composed of thin-walled, hyaline cells of textura prismatica in the basal and lateral part, becoming thick-walled, dark brown to black cells of textura angularis in the ostiolar region. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 6–17 × 4–7 µm, hyaline, enteroblastic, short cylindrical to subcylindrical, smooth-walled, with periclinal thickenings at upper part. Conidia 8.6–16.6 × 9–14 µm ( = 13 × 10 µm; n = 30), hyaline, ellipsoidal to obovoid or globose, bulging in the upper half, rounded and occasionally invaginated at apex, truncate at base and bearing minute marginal frills, enclosed in a distinct mucoid envelope 0.7–2 µm wide, with a single, unbranched, attenuated, mucoid, apical appendage (5.5–8 µm long). Spermatogenous cells hyaline, ampulliform to lageniform or subcylindrical, with periclinal thickenings, smooth-walled. Spermatia hyaline, bacillar with a narrowed apical part and a swollen, truncate basal part bearing minute marginal frills, unicellular, smooth-walled (description of spermatogenous cells and spermatia adapted from Nag Raj 1993).
Material examined: Canada, Ontario, Waterloo, University of Waterloo campus, on leaves of Aesculus hippocastanum (Sapindaceae), 27 July 1988, T.R. Nag Raj (DAOM 215312).
Notes: Phyllosticta sphaeropsoidea has been recoded from Austria, Canada, and USA. This species is associated with leaf blotch disease on A. glabra and A. hippocastanum. The infection is often severe enough to cause premature defoliation (Nag Raj 1993).
Phyllosticta sphaeropsoidea (DAOM 215312) a, b Herbarium package and specimen. c–d Appearance of pale brown to brown conidiomata on the host. e–f Vertical sections of conidiomata. g–h Sections of peridium. i Ostiole. j–m Conidiogenous cells and developing conidia. n–s Conidia. Scale bars c = 200 µm, d = 100 µm, e–f = 100 µm, g–h = 10 µm, i = 20 µm, j–s = 5 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.