Cercospora cyperina Nguanhom, Crous & U. Braun, 2015

Nguanhom, Jeerapa, Cheewangkoon, Ratchadawan, Groenewald, Johannes Z., Braun, Uwe, To-Anun, Chaiwat & Crous, Pedro W., 2015, Taxonomy and phylogeny of Cercospora spp. from Northern Thailand, Phytotaxa 233 (1), pp. 27-48 : 42

Cercospora cyperina Nguanhom, Crous & U. Braun , sp. nov. ( Fig. 4 ). MycoBank MB812920

Type: — THAILAND. Chiang Mai: on leaves of Cyperus alternifolius ( Cyperaceae ), 12 May 2013, S. Seekanha (holotype CBS H-22291, culture ex-type CPC 23919 = CBS 140166).

Leaf spots amphigenous, pale brown to brown, margin indefinite, elongated to irregular. Mycelium internal. Caespituli amphigenous, punctiform, brown. Stromata none or composed of 2−3 brown cells. Conidiophores loosely fasciculate, with fascicles of 2−9 conidiophores, brown, paler towards the apex, cylindrical to geniculate, somewhat constricted at septa, branched, 2−6-septate, 73−138 × 5−6 μm. Conidiogenous cells proliferating sympodially 1−6 times, integrated, terminal and intercalary, 20–38 μm long; conidiogenous loci conspicuous, thickened and darkened, multi-local, formed apical or on shoulders caused by proliferation, 2.5−4 μm diam. Conidia solitary, hyaline, thin-walled, smooth, acicular to somewhat obclavate, subobtuse at the apex, truncate to slightly obconically truncate at the base, 55−155 × 2.5−4 μm, indistinctly 15–20-septate, hila slightly thickened, darkened and refractive, 2.5–3 μm diam.

Culture characteristics:— Colonies spreading, low convex, with sparse to moderate aerial mycelium, entire margin and folded surface, reaching 44 mm diam after 2 wk. On MEA surface whitish with patches of greyish rose; reverse olivaceous-black. On PDA surface whitish, pale grey at the centre with diffuse red pigment surrounding the colony; reverse olivaceous-black. On OA whitish with patches of pale grey, but red at the margin; reverse olivaceous-grey.

Etymology: —Epithet derived from the host genus, Cyperus .

Notes: — Cercospora cyperina is morphologically close to C. cyperi Sawada ( Braun et al. 2014) but distinct by having longer, distinctly geniculate conidiophores with constrictions and much larger conidiogenous loci, 3–4 μm diam [conidiophores (10–)20–90 μm long, without constrictions, loci (1–)1.5–2(–2.5) μm diam in C. cyperi ]. This taxon was also supported as a new species based on its distinct phylogenetic position. In the combined tree ( Fig. 1 ), it is sister to C. cyperacearum and thus separate from other species occurring on Cyperus .

Figures

FIGURE 1. The Bayesian 50% majority rule consensus tree derived from the combined ITS/cmdA alignment. Bayesian posterior probabilities support values for the respective nodes are displayed in the tree. The scale bar indicates 0.01 expected changes per site and species are delimited by blocks of different colours. Strain accession numbers from Thailand and names of species containing Thai strains are printed in bold face. The tree was rooted to Septoria provencialis CPC 12226 (ITS GenBank DQ303096, cmdA GenBank JX143030).

FIGURE 4. Cercospora cyperina (CBS H-22291). A. Leaf spot; B. Close-up of leaf spot; C, D. Conidiophores and conidiogenous cells; E−H. Conidia; I. Colony on MEA.—Scale bars: C−D = 40 μm; E−H = 50 μm, and G applies to H.