Phyllosticta minima
Phyllosticta minima (Berk. & M.A. Curtis) Underw. & Earle, Bull. Alabama Agric. Exp. Stn. 80: 168. 1897.
Index Fungorum: IF425100; Facesoffungi: FoFxxxxx; MycoBank: MB425100.
Pathogenic on leaf spot of Acer rubrum. Sexual morph: Unknown. Asexual morph: Conidiomata (on PNA) up to 180 μm diam., pycnidial, solitary, black, erumpent, globose, exuding colourless conidial masses. Peridium up to 30 μm thick, composed of several layers of textura angularis, inner wall of hyaline textura angularis. Ostiole up to 15 μm diam., central. Conidiophores 15–50 × 5–6 μm, subcylindrical to ampulliform, reduced to conidiogenous cells, or with 1–2 supporting cells, that can be branched at the base. Conidiogenous cells 8–20 × 3–4 μm, terminal, subcylindrical, hyaline, smooth, coated in a mucoid layer, proliferating several times percurrently near apex. Conidia (9–)10–11(–12) × (6–)7(–8) μm, solitary, hyaline, aseptate, thin and smooth walled, granular, or with a single large central guttule, broadly ellipsoid to obovoid or globose, tapering towards a narrow truncate base, 2–3 μm diam., enclosed in a thin mucoid sheath, absent at maturity or 1 μm thick, and bearing a hyaline, apical mucoid appendage, 6–7(–10) × 1.5(–2) μm, flexible, unbranched, tapering towards an acute tip.
Culture characteristics: Colonies flat, spreading with sparse aerial mycelium and feathery, lobate margins, reaching 15 mm diam. on MEA, 40 mm diam. on PDA and 8 mm diam. on OA after 2 wk at 25 ºC. On OA surface olivaceous-grey. On PDA surface and reverse iron-grey. On MEA surface olivaceous-grey with patches of pale luteus.
Representative isolate: USA, North Dakota, New England, on Acer rubrum, R. Sprague 5314 (holotype not found); Tennessee, Gatlinburg, Great Smoky Mountains National Park, on leaf spot of Acer rubrum, June 1984, D.H. Defoe, neotype CBS H-17023, CBS 585.84 = IFO 32917 = MBT176250 (ex-neotype culture).
Host: Acer rubrum (Wikee et al. 2013).
Known distribution: USA (Wikee et al. 2013).
GenBank Numbers: ITS - KF206176, LSU - KF206286, TEF - KF289204, ACT - KF289249, GPDH - KF289135.
Note: This taxon appears to be common on Acer species in USA, where it is associated with leaf spots (Bissett & Darbyshire 1984). The holotype could not be located in NY, LCR, IMI, S, K or BPI, and thus Wikee et al. (2013) designated a neotype (from the original host in the USA).
References:
Bissett J, Darbyshire SJ (1984) Phyllosticta minima. Fungi Canadenses: 277. National Mycological Herbarium, Biosystematics Research Institute, Agriculture Canada, Ottawa, Canada.
Wikee S, Lombard L, Nakashima C, Motohashi K, Chukeatirote E, Cheewangkoon R, McKenzie EHC, Hyde KD, Crous PW (2013) A phylogenetic re-evaluation of Phyllosticta (Botryosphaeriales). Studies in Mycology 76: 1–29.