Pseudocercospora sp. A

Bakhshi, Mounes, Arzanlou, Mahdi, Babai-Ahari, Asadollah, Groenewald, Johannes Z. & Crous, Pedro W., 2014, Multi-gene analysis of Pseudocercospora spp. from Iran, Phytotaxa 184 (5), pp. 245-264 : 256-257

Pseudocercospora sp. A ( Fig. 8 )

Description in planta:— Leaf spots amphigenous, irregular to angular, 3–7 mm diam., olivaceous-green. Mycelium internal. Caespituli predominantly hypophyllous, evenly distributed over the leaf spot, olivaceous brown on leaves. Stromata weakly developed, substomatal to intraepidermal, semi-immersed, globular, 10–25 μm diam. Conidiophores arranged in loose fascicles, arising from stromata, through stomata or erumpent through the cuticle, medium brown, smooth, 0–2-septate, mostly unbranched, rarely branched below, straight to curved, subcylindrical to conical (when reduced to conidiogenous cells), wider at the base, apex subtruncate, (12–)18–25(–40) × 3–4.5(–5.5) μm. Conidiogenous cells terminal, or conidiophores reduced to conidiogenous cells, medium brown, smooth, (8–)14–17(–25) × 3–4(–5) μm, proliferating sympodially near the apex, with flat-tipped loci, 1–2 µm diam., loci neither thickened nor darkened. Conidia solitary, subhyaline to pale brown, guttulate, subcylindrical to obclavate, apex obtuse to subacute, base obconically truncate, straight to gently curved, 3–8-septate, (35–)52–60(–80) × 2–4 μm; hila neither thickened nor darkened or refractive, 1–2 μm diam.

Cultural characteristics:— Colonies on MEA reaching 30 mm diam. after 20 days at 25 ºC in the dark; surface folded, erumpent with sparse aerial mycelium and even margins. Surface olivaceous-grey, reverse iron-grey.

Material examined:— IRAN. Guilan Province: Sowme’eh Sara, Dogour, on Phaseolus vulgaris L. ( Fabaceae ), August 2012, M. Bakhshi ( CCTU 1165 = CBS 136113). Sowme’eh Sara, Dogour, on Phaseolus vulgaris , August 2012, M. Bakhshi ( CCTU 1166).

Notes:— Two species of Pseudocercospora , namely P. cruenta and P. griseola , have thus far been reported from Phaseolus vulgaris ( Crous & Braun 2003) . Pseudocercospora sp. A is phylogenetically ( Fig. 2 ) and morphologically well distinguished from P. griseola ( Crous et al. 2006) by its short, fasciculate conidiophores and subcylindrical to obclavate, narrower conidia . Other than having shorter conidia , Pseudocercospora sp. A is morphologically indistinguishable from P. cruenta . However , in the multi-gene tree ( Fig. 2 ), Pseudocercospora sp. A forms a wellsupported clade which is distinct from P. cruenta (on Vigna sp. from Trinidad, North America ). The type of P. cruenta is from North America, but the species has not been epitypified, thus Pseudocercospora sp. A remains unresolved until DNA sequence data from the type locality has been made available .

Figures

FIGURE 2. A Bayesian inference phylogenetic tree of 59 isolates of Pseudocercospora. The tree was built using concatenated sequences of the ITS, ACT and TEF1-α loci, each with a separate model of DNA evolution. Species clades from Iran are indicated in green coloured blocks and species names in black text. Culture accession numbers are listed along with host plant (orange text) and place of origin (dark blue text). The tree was rooted to Passalora eucalypti (CBS 111318). Bayesian posterior probabilities ≥ 0.95 are indicated with colourcoded branches and scale bar indicates number of expected changes per site.

FIGURE 8. Pseudocercospora sp. A. a. Leaf spots. b–e. Fasciculate conidiophores with some conidiophores reduced to conidiogenous cells. f–j. Conidia. Scale bars = 10 µm.