Taxonomy

All taxonomic descriptions are based on structures from herbarium material. Diseased leaf tissues were observed under a stereo-microscope and relevant morphological structures (stromata, conidiophores and conidia) were picked up from lesions with a sterile inoculation needle and mounted on glass slides in clear lactic acid. Thirty measurements were made at × 1 000 magnification using a Nikon Eclipse 80i light microscope for each microscopic structure, and 95 % confidence intervals were derived for the measurements with extreme values given in parentheses. High-resolution photographic images of microscopic fungal structures were captured with a Nikon digital sight DS-f1 high definition colour camera mounted on the Nikon Eclipse 80i light microscope. Adobe Photoshop CS3 was used for the final editing of acquired images and photographic preparations. Colony colours on MEA were determined after 1 mo at 25 °C in the dark in duplicate. The mycological colour charts of Rayner (1970) were used to define colours of the fungal colonies. Nomenclatural novelties and descriptions were deposited in MycoBank (www.MycoBank.org; Crous et al. 2004a). The naming system for tentatively applied names used by Groenewald et al. (2013) is continued in this manuscript to simplify comparison between the studies.

Taxonomy

The Consolidated Species Concept was employed in this study to distinguish species, revealing a rich diversity among the Cercospora species studied. Twenty lineages of Cercospora from Iran were resolved based on the clustering and support in the Bayesian tree obtained from the combined ITS, TEF1-α, ACT, CAL and HIS alignment (Fig. 1). Data are alphabetically summarised in Table 1. Eight species including C. althaeina, C. apii (species complex), C. armoraciae (species complex), C. beticola, C. chenopodii, C. rumicis, C. violae and C. zebrina were assigned to existing species names. Three more species including C. cf. flagellaris (species complex), C. cf. richardiicola and C. cf. zinniae were morphologically similar to existing species, but as explained by Groenewald et al. (2013), these names could not be applied in cases where the ex-type strain was unavailable. In these cases, species were indicated with ‘cf.’ in the species name.

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Fig. 1

Consensus phylogram (50 % majority rule) of 43 082 trees resulting from a Bayesian analysis of the combined 5-gene sequence alignment using MrBayes v. 3.2.1. Bayesian posterior probabilities are indicated with colour-coded branches and numbers (see legend) and the scale bar indicates 0.2 expected changes per site. Lineages from Iran are indicated in coloured blocks and species names in black text. Hosts and provinces of origin are indicated in green and brown text, respectively. The tree was rooted to Ramularia endophylla (isolate CBS 113265).

In addition, several new hosts were recognised for the previously known Cercospora species including C. apii, C. armoraciae, C. beticola, C. cf. richardiicola, C. rumicis, Cercospora sp. G and C. zebrina. Novel host records are shown with an asterisk in Table 1. Cercospora cf. flagellaris and Cercospora sp. G sensu Groenewald et al. (2013), two species with wide host ranges (infecting 18 and six host families respectively in this study), were common species in the sampled areas, and sometimes these two species infected the same host at the same time.

Furthermore, eight additional lineages were recognised in this study. Identification of these lineages required careful morphological comparison and consideration of host-fungus relationships, as well as knowledge of the relevant scientific literature (Crous & Braun 2003) and databases (Systematic Mycology and Microbiology Laboratory (SMML), http://nt.ars-grin.gov/fungaldatabases/fungushost/fungushost.cfm).

Cercospora chenopodii Fresen., Beitr. Mykol.: 92. 1863 — Fig. 2

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Fig. 2

Cercospora chenopodii (CCTU 1033). a. Leaf spots; b. c. fasciculate conidiophores; d–g. conidia. — Scale bars = 10 μm.

Additional synonyms in Groenewald et al. (2013)

Description in planta — Leaf spots amphigenous, distinct, circular to subcircular, 2–6 mm diam, pale brown with black dots (stroma with conidiophores), definite margin, surrounded by a dark pink border. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in dense fascicles (5–35), arising from the upper cells of a moderately developed brown stroma, up to 70 μm wide; conidiophores medium brown, becoming pale brown towards the apex, 2–8-septate, straight to variously curved, unbranched, (40–)62–72(–90) × 4–6 μm, width of conidiogenous cells immediately behind the fertile region is often narrower. Conidiogenous cells intercalary and terminal, unbranched, pale brown, smooth, proliferating sympodially, 20–50 × 4–6 μm, mostly mono-local, sometimes multi-local; loci thickened, darkened, protuberant, refractive, apical or lateral, 2–3.5 μm diam. Conidia solitary, smooth, subcylindrical, straight to slightly curved, hyaline, distinctly (0–) 2 – 4 (– 5)-septate, apex obtuse, base obconically truncate, sometimes constricted at the septa, (20–)27– 32(–40) × 5– 6(–7) μm; hila thickened, darkened, refractive, 2 – 4 μm diam.

Specimens examined. IRAN, Guilan Province, Talesh, on leaves of Chenopodium album (Chenopodiaceae), Sept. 2011, M. Bakhshi, CCTU 1033; Guilan Province, Bandar-e Anzali, on leaves of C. album (Chenopodiaceae), June 2012, M. Bakhshi, CCTU 1060; Guilan Province, Langroud, on leaves of C. album (Chenopodiaceae), Aug. 2012, M. Bakhshi, CCTU 1157; Guilan Province, Lahijan, on leaves of C. album (Chenopodiaceae), Aug. 2012, M. Bakhshi, CCTU 1163.

Cercospora convolvulicola M. Bakhshi, Arzanlou, Babaiahari, Crous & U. Braun, sp. nov. — MycoBank MB809116; Fig. 3

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Fig. 3

Cercospora convolvulicola (CBS 136126). a. Leaf spots; b. c. fasciculate conidiophores; d–j. conidia. — Scale bars = 10 μm.

Etymology. Named after the host genus on which it was collected, Convolvulus.

Description in planta — Leaf spots circular to subcircular, 2–8 mm, grey-brown to brown, not surrounded by margin of different colour. Mycelium internal. Caespituli amphigenous, brown. Conidiophores straight or sinuously geniculate, in dense fascicles, arising from the upper cells of a well-developed, intraepidermal and substomatal, brown stroma, up to 40 μm diam; conidiophores pale brown to brown, simple, rarely branched, moderately thick-walled, irregular in width, attenuated at the upper portion, often constricted at septa and proliferating point, 35–50(–70) × (3–)4–6 μm, 2–5-septate. Conidiogenous cells intercalary and terminal, proliferating sympodially, 10–20 × 3–5.5 μm, multi-local; loci distinctly thickened, apical, lateral or formed on the shoulders caused by geniculation, sometimes circumspersed, protuberant, 1.5–2.5 μm. Conidia solitary, hyaline, subcylindrical to obclavate, straight or slightly curved, truncate to somewhat obconically truncate at the base, subacute or subobtusely rounded at the apex, 35–50(–65) × (2.5–)3.5–4.5 μm, 3–8-septate, guttulate; hila thickened, darkened, refractive, 1.5–2.5 μm diam.

Cultural characteristics — Colonies on MEA reaching 55 mm diam after 20 d at 25 °C in the dark; flat with smooth, even margins and moderate aerial mycelium; surface olivaceous-grey, reverse dark iron-grey.

Specimens examined. IRAN, Ardabil Province, Moghan, on Convolvulus arvensis (Convolvulaceae), Oct. 2011, M. Bakhshi (holotype IRAN 16454 F, culture ex-type CCTU 1083 = CBS 136126); Moghan, on C. arvensis (Convolvulaceae), Oct. 2011, M. Bakhshi, CCTU 1083.2.

Notes — Based on individual gene trees, the two isolates representing this species are never supported in their own clade; in the TEF1-α and ACT phylogenies, they are intermixed with C. cf. flagellaris and C. cf. brunkii; in the CAL phylogeny with C. apii and C. cf. brunkii, and in the HIS phylogeny with C. rodmanii, C. cf. zinniae and Cercospora spp. N, P and Q sensu Groenewald et al. (2013). Shared alleles are the likely cause for the separate position of C. convolvulicola in the combined phylogeny (Fig. 1, part 3). Cercospora convolvulicola is sister to C. cf. brunkii and appears to be specific to Convolvulus arvensis. The only species known from Convolvulus arvensis, is C. ipomoea. Cercospora cf. ipomoea (tentative name for C. ipomoea) has a different phylogenetic position. Cercospora convolvulicola differs morphologically from C. ipomoea, by having dense conidiophores and shorter, guttulate, subcylindrical to obclavate conidia (Fig. 3).

Cercospora conyzae-canadensis M. Bakhshi, Arzanlou, Babai-ahari, Crous & U. Braun, sp. nov. — MycoBank MB809117; Fig. 4

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Fig. 4

Cercospora conyzae-canadensis (CBS 135978). a. Leaf spots; b. c. fasciculate conidiophores; d–h. conidia. — Scale bars = 10 μm.

Etymology. Named after the host plant from which it was collected, Conyza canadensis.

Description in planta — Leaf spots amphigenous, circular, 1–4 mm diam, grey to pale brown with dark brown margins. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in loose fascicles (3–15), arising from a weakly developed, intraepidermal and substomatal, dark brown stroma, up to 30 μm diam; conidiophores brown to dark brown, 2–6-septate, straight to geniculate-sinuous due to sympodial proliferation, simple, thick-walled, uniform in width, often constricted at the proliferating point, (57–)97–112(–140) × 4.5–5.5 μm. Conidiogenous cells intercalary and terminal, pale brown to brown, proliferating sympodially, 20–40 × 4–5.5 μm, multi-local; loci distinctly thickened, darkened and somewhat refractive, apical or formed on shoulders caused by sympodial proliferation, 2–3.5 μm diam. Conidia solitary, filiform to obclavate-cylindrical, straight to slightly curved, hyaline, (32–)60–94(–170) × 3.5–5.5 μm, (3–)7–12(–17)-septate, with subobtusely rounded apices and truncate to obconically truncate bases; hila thickened, darkened, refractive, 1.5–2.5 μm diam.

Cultural characteristics — Colonies on MEA reaching 24 mm diam after 20 d at 25 °C in the dark; erumpent with smooth, irregular margins and sparse aerial mycelium; dark olivaceous-green on the surface, dark blue-green underneath.

Specimens examined. IRAN, Guilan Province, Talesh, on Conyza canadensis (Asteraceae), Nov. 2012, M. Bakhshi (holotype IRAN 16455 F, culture ex-type CCTU 1119 = CBS 135978); Talesh, on C. canadensis (Asteraceae), Aug. 2011, M. Bakhshi, CCTU 1008; Zanjan Province, Tarom, on C. canadensis (Asteraceae), Aug. 2012, M. Bakhshi, CCTU 1105.

Notes — Cercospora conyzae-canadensis must be regarded as a new species, based on its distinct phylogenetic position. In the individual gene trees (ACT, TEF1-α, CAL and HIS), it is distinguished from all other species. In the combined tree (Fig. 1, part 1), it is a sister taxon to the clade including C. cf. modiolae and Cercospora sp. E sensu Groenewald et al. (2013). Three species of Cercospora, including C. bidentis, C. erigeronicola and C. nilghirensis, have been reported from Conyza. Cercospora conyzae-canadensis is morphologically distinguished from those species by its moderately developed stroma, loose fascicles and dark brown conidiophores. Cercospora erigeronicola is distinct in having shorter and narrower, 0–3-septate conidia, 15–45 × 2–3.5 μm. Cercospora conyzae-canadensis is morphologically close to C. nilghirensis in conidial shape and size. However C. nilghirensis, described from India on Conyza ambigua, lacks stromata and has numerous longer conidiophores that are densely fasciculate. Cercospora conyzaecanadensis appears to be specific to Conyza canadensis.

Cercospora cylindracea M. Bakhshi, Arzanlou, Babai-ahari, Crous & U. Braun, sp. nov. — MycoBank MB809118; Fig. 5

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Fig. 5

Cercospora cylindracea (CBS 138580). a. Leaf spots on Cichorium intybus; b. leaf spots on Lactuca serriola; c–e. fasciculate conidiophores; f–k. conidia. — Scale bars = 10 μm.

Etymology. Name derived from the cylindrical conidia.

Description in planta — Leaf spots distinct, circular to subcircular, sometimes angular, pale brown, with broad brown margin, sometimes appearing as an eye spot, 1–7 mm diam. Mycelium internal. Caespituli amphigenous, brown. Conidiophores in divergent fascicles (4–25), arising from the upper cells of a moderately to well-developed, intraepidermal and substomatal, brown stroma, up to 30 μm diam; conidiophores pale brown to brown, thick-walled, 1–6-septate, straight, sinuous to distinctly geniculate, flexuous, (35–)55–65(–90) × 4–5.5 μm, irregular in wide, conically narrowed at the apex. Conidiogenous cells terminal or intercalary, unbranched, pale brown, smooth, proliferating sympodially, 15–30 × 3.5–5 μm, multi-local; loci thickened, darkened, refractive, protuberant, apical, lateral or circumspersed, 1.5–2.5 μm diam. Conidia solitary, subcylindrical to cylindrical, straight to mildly curved, hyaline, distinctly 1–10-septate, obtuse at the apex, subtruncate at the base, (30–)45–60(–90) × 3.5–5.5 μm; hila thickened, darkened, refractive, 1.5–2.5 μm diam.

Cultural characteristics — Colonies on MEA reaching 62 mm diam after 20 d at 25 °C in the dark; erumpent, folded, with smooth, even margins and sparse to moderate aerial mycelium; surface olivaceous-grey, reverse dark olivaceous-grey.

Specimens examined. IRAN, Ardabil Province, Moghan, on Lactuca serriola (Asteraceae), Sept. 2011, M. Bakhshi (holotype IRAN 16468 F, culture ex-type CCTU 1081 = CBS 138580); Moghan, on L. serriola (Asteraceae), Oct. 2012, M. Bakhshi, CCTU 1207; West Azerbaijan Province, Khoy, on Cichorium intybus (Asteraceae), June 2011, M. Arzanlou, CCTU 1016; Khoy, on L. serriola (Asteraceae), Sept. 2011, M. Arzanlou, CCTU 1044 = CBS 136021; Khoy, on L. serriola (Asteraceae), Sept. 2011, M. Arzanlou, CCTU 1049; Khoy, on L. serriola (Asteraceae), Sept. 2012, M. Arzanlou, CCTU 1183; Khoy, on L. serriola (Asteraceae), Sept. 2012, M. Arzanlou, CCTU 1189; Zanjan Province, Tarom, on C. intybus (Asteraceae), Oct. 2011, M. Bakhshi, CCTU 1114.

Notes — Cercospora cylindracea clusters as a sister taxon to the C. althaeina clade in the combined tree (Fig. 1, part 3). The host range of C. cylindracea is limited to Lactuca serriola and Cichorium intybus (both in the Asteraceae). Cercospora cylindracea is distinguished from C. althaeina in the HIS and ACT phylogenies but not in the TEF1-α phylogeny. In the CAL phylogeny, isolates are intermixed with those of C. zebrina, Cercospora sp. L sensu Groenewald et al. (2013) and C. althaeina. Three species of Cercospora including C. apii, C. lactucasativae and C. cichorii, are known from Lactuca serriola and Cichorium intybus. Cercospora cylindracea is separated in the combined gene tree from C. apii and C. lactucae-sativae as circumscribed in Groenewald et al. (2013) who studied Japanese material on Lactuca satica. Cercospora cylindracea differs from C. cichorii and C. lactucae-sativae by its cylindrical to subcylindrical conidia. Furthermore, the conidiogenous loci in C. lactucae-sativae are broader, 2.5–3.5 μm, than in C. cylindracea.

Cercospora iranica M. Bakhshi, Arzanlou, Babai-ahari, Crous & U. Braun, sp. nov. — MycoBank MB809119; Fig. 6

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Fig. 6

Cercospora iranica (CBS 136124). a. Leaf spots; b. fasciculate conidiophores; c–h. conidia. — Scale bars = 10 μm.

Etymology. Named after Iran, the country of the type location.

Description in planta — Leaf spots amphigenous, circular, 1–7 mm, first appearing as red-brown spots, later centre becoming grey with red-brown borders on upper and lower surface. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in moderately dense fascicles (8–20), arising from a well-developed, erumpent, dark brown stroma, up to 40 μm diam; conidiophores brown, becoming pale brown towards the apex, 2–6-septate, straight to geniculate-sinuous due to sympodial proliferation, simple, uniform in width, sometimes constricted at the proliferating point, (30–)62–71(–90) × 4–5.5(–6) μm. Conidiogenous cells intercalary and terminal, pale brown to brown, proliferating sympodially, 15–35 × 4–5 μm, multi-local; loci distinctly thickened, darkened and somewhat refractive, apical, lateral or formed on shoulders caused by geniculation, 2–3.5 μm diam. Conidia solitary, obclavate when smaller, longer ones filiform to acicular, straight to slightly curved, hyaline, (27–)52–67(–95) × 2–4 μm, (3–)7–10(–14)-septate, with subobtusely rounded apices and truncate or long obconically truncate bases; hila thickened, darkened, refractive, 1.5–2 μm diam.

Cultural characteristics — Colonies on MEA reaching 60 mm diam after 20 d at 25 °C in the dark; erumpent with smooth, even margins and moderate aerial mycelium; surface pale grey-olivaceous in centre, vinaceous-grey in outer region, reverse iron-grey in centre, dark pink-grey in outer region.

Specimens examined. IRAN, Guilan Province, Astara, on leaves of Vicia faba (Fabaceae), June 2012, M. Bakhshi (holotype IRAN 16466 F, culture ex-type CCTU 1137 = CBS 136124); Astara, on leaves of V. faba (Fabaceae), June 2012, M. Bakhshi, CCTU 1137.2; Mazandaran Province, Ramsar, on leaves of Hydrangea sp. (Hydrangeaceae), Sept. 2012, M. Bakhshi, CCTU 1196 = CBS 136123.

Notes — In the TEF1-α, HIS and ACT phylogeny, isolates of C. iranica and Cercospora sp. T cluster together in a distinct well-supported clade. In the CAL phylogeny, C. iranica forms a distinct clade, whereas Cercospora sp. T cannot be distinguished from Cercospora spp. M, O, P and Q (sensu Groenewald et al. 2013), nor from C. alchemillicola and C. cf. sigesbeckiae. The different CAL sequences explain the basal position of Cercospora sp. T to the C. iranica clade in the combined phylogeny (Fig. 1, part 1). Cercospora zonata, the causal agent of Cercospora leaf spot of faba beans (Kimber 2011) is morphologically quite distinct from C. iranica in having much broader (3–6 μm) obclavate-cylindrical conidia with short obconical base and larger hila, 2–2.5 μm wide (various collections examined, including topotype material of C. zonata: on Vicia faba, Portugal, May 1884, F. Moller, Rabenh., Fung. Eur. Exs. 3294, B, HAL). Caespituli that arise from a well-developed, erumpent stroma on the leaf surface is a unique morphological character of this species on Vicia faba.

Cercospora pseudochenopodii M. Bakhshi, Arzanlou, Babaiahari & Crous, sp. nov. — MycoBank MB809120; Fig. 7

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Fig. 7

Cercospora pseudochenopodii (CBS 136022). a. Leaf spots; b. c. fasciculate conidiophores; d–h. conidia. — Scale bars = 10 μm.

Etymology. Named after its superficial resemblance to Cercospora chenopodii.

Description in planta — Leaf spots amphigenous, circular to irregular, 5–12 mm diam, pale brown, with concentric rings on adaxial and abaxial surface (stroma with conidiophores), indefinite margin, not surrounded by a border of different colour. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in dense fascicles (8–40), emerging through stomatal openings or erumpent through the cuticle, arising from the upper cells of a moderately developed brown stroma, up to 60 μm wide; conidiophores pale brown to brown, 2–5-septate, thick-walled, mainly straight, sometimes geniculate in upper part, unbranched, almost uniform in width, (32–)39–45(–60) × (3.5–)4.5–5(–6.5) μm. Conidiogenous cells terminal, unbranched, pale brown, smooth, tapering to flat-tipped apical loci, proliferating sympodially, 10–30 × 3.5–6.5 μm, mostly mono-local, sometimes multi-local; loci apical or formed on shoulders caused by geniculation, thickened, darkened, protuberant, somewhat refractive, 2–4 μm diam. Conidia solitary, guttulate, cylindrical to subcylindrical, straight to slightly curved, hyaline, (0–)2–4(–5)-septate, apex obtuse, base obconically truncate, (25–)37–44.5(–70) × (4–)5–5.5(–7) μm; hila thickened, darkened, refractive, 2–4 μm diam.

Cultural characteristics — Colonies on MEA reaching 24 mm diam after 20 d at 25 °C; smooth to folded, erumpent with even margins and moderate aerial mycelium; surface smoke-grey in centre, olivaceous-grey in outer region; reverse olivaceous-grey.

Specimens examined. IRAN, Zanjan Province, Tarom on leaves of Chenopodium sp. (Chenopodiaceae), 26 Sept. 2011, M. Bakhshi (holotype IRAN 16467 F, culture ex-type CCTU 1038 = CBS 136022); West Azerbaijan Province, Khoy, on Chenopodium sp. (Chenopodiaceae), 20 Sept. 2011, M. Arzanlou, CCTU 1045; Khoy, on leaves of C. album (Chenopodiaceae), 1 Sept. 2012, M. Arzanlou, CCTU 1176.

Notes — Groenewald et al. (2013) regarded this species as a cryptic taxon, C. cf. chenopodii, since they did not have sufficient isolates of C. chenopodii for comparison. In the present study, we have included additional collections of both species. Based on robust phylogenetic differences, C. pseudochenopodii must be regarded as a distinct species. There are slight differences in morphology and symptoms between C. chenopodii and C. pseudochenopodii, i.e., leaf spots with concentric rings without definite margins; conidia slightly longer and narrower (Fig. 7), which refer only to the collections examined. Cercospora chenopodii is widespread and represented by numerous collections. The two species are, however, indistinguishable, and can only be differentiated by DNA sequence analyses. Cercospora pseudochenopodii has distinct ACT and HIS phylogenies, but based on CAL sequence data, it cannot be differentiated from C. chenopodii. In the ITS and TEF1-α phylogeny, C. pseudochenopodii is intermixed with some other species, but it is distinct from C. chenopodii. In the combined tree (Fig. 1, part 2), it sits in a well-supported clade sister to C. chenopodii.

Cercospora solani Thüm., Hedwigia 19: 135. 1880 and Contr. Fl. Mycol. Lusat. II: 15. 1880 — Fig. 8

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Fig. 8

Cercospora solani (CBS 136038). a. Leaf spots; b. c. fasciculate conidiophores; d–h. conidia. — Scale bars = 10 μm.

Description in planta — Leaf spots amphigenous, subcircular to irregular, 8–27 mm diam, with grey to black dots (stroma with conidiophores) and dark grey margins. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in moderately dense fascicles (6–20), arising from a well-developed, intraepidermal and substomatal, brown stromata, 10–55 μm diam; conidiophores pale brown to brown, 2–6-septate, straight to geniculate-sinuous due to sympodial proliferation, simple, rarely branched, almost uniform in width, often constricted at the proliferating point, (45–)64–75(–100) × 4–5 μm. Conidiogenous cells intercalary and terminal, pale brown to brown, tapering to flat-tipped apical loci, proliferating sympodially, 20–35 × 4–5 μm, multi-local; loci distinctly thickened, darkened and somewhat refractive, apical or formed on shoulders caused by geniculation, 2–3.5 μm diam. Conidia solitary, subcylindrical or somewhat narrowed towards the tip, straight to slightly curved, hyaline, thin-walled, (26–)48–59(–92) × (3.5–)4.5–5.5 μm, distinctly (2–)3–7(–8)-septate, with subobtusely rounded apices and truncate bases; hila distinctly thickened, darkened, refractive, 1.5–2.5 μm diam.

Cultural characteristics — Colonies on MEA slow growing, reaching 15 mm diam after 20 d at 25 °C in the dark; erumpent with smooth, even margins and sparse aerial mycelium; grey-olivaceous on the surface, reverse iron-grey.

Specimens examined. IRAN, West Azerbaijan Province, Khoy, on leaves of Solanum nigrum (Solanaceae), Sept. 2011, M. Arzanlou, CCTU 1043 = CBS 136038; Khoy, on leaves of S. nigrum (Solanaceae), Sept. 2011, M. Arzanlou, CCTU 1050.

Notes — Cercospora solani is supported in all of the individual gene trees. In the combined tree, it is a sister taxon to the clade including C. conyzae-canadensis, C. cf. modiolae and Cercospora sp. E sensu Groenewald et al. (2013) (Fig. 1, part 1). Ten species of Cercospora have been reported from Solanum, including C. apii, C. canescens, C. lanugiflori, C. physalidis, C. puyana, C. sciadophila, C. solanacea, C. solani, C. solanigena and C. solani-nigri. Cercospora solani is phylogenetically distinct from C. apii, C. canescens and C. physalidis. Among the other candidate species, the status of C. lanugiflorii, C. sciadophila and C. solanigena are uncertain, as their type collections are lacking (Crous & Braun 2003); symptoms of C. puyana are different, and C. solanacea has been reduced to synonymy with Pseudocercospora trichophila var. punctata (Braun & Urtiaga 2013). Cercospora solani-nigri is also a Pseudocercospora and heterotypic synonym of P. atromarginalis (type material examined by U. Braun: on Solanum nigrum, India, Poona, 18 Dec. 1957, P.P. Chiddarwar, BPI 441404). The description of C. solani in Chupp (1954) is misleading. It is unclear on which collections Chupp‘s (1954) description was based. The name C. solani has often been confusingly applied. However, type material of C. solani has been examined by U. Braun (on Solanum nigrum, Portugal, Coimbra, Jan. 1879, F. Moller, Thüm., Mycoth. Univ. 2070, HAL) and was shown to be a true Cercospora s.str. characterised by cylindrical to subacicular (somewhat apically attenuated) conidia. The type of C. solani agrees well with the present material from Iran.

Cercospora sorghicola M. Bakhshi, Arzanlou, Babai-ahari, Crous & U. Braun, sp. nov. — MycoBank MB809121; Fig. 9

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Fig. 9

Cercospora sorghicola (CBS 136448). a. Leaf spots; b. c. fasciculate conidiophores; d–h. conidia. — Scale bars = 10 μm.

Etymology. Derived from the host genus, Sorghum.

Description in planta — Leaf spots amphigenous, initially dark purple spots that enlarge over time into linear-oblong lesions with dark purple centre and dark red-purple margins, 5–35 mm long. Mycelium internal. Caespituli amphigenous, brown.

Conidiophores aggregated in loose or dense fascicles (5–40), arising from the upper cells of a well-developed, intraepidermal and substomatal, brown stroma, up to 50 μm diam; conidiophores pale brown to brown, paler towards the apex, simple, unbranched, 1–8-septate, straight or flexuous caused by sympodial proliferation, almost uniform in width, sometimes conical at the apex, (45–)70–80(–100) × 4–5.5 μm. Conidiogenous cells terminal or intercalary, unbranched, pale brown, smooth, proliferating sympodially, 20–40 × 3.5–5.5 μm, multi-local; loci thickened, darkened, refractive, protuberant, apical, lateral, 2–4 μm diam. Conidia solitary, smooth, acicular, cylindro-obclavate to obclavate, straight or curved, successively tapering towards the apex, hyaline, (3–)8–13(–17)-septate, apex subacute to subobtuse, base truncate to obconically truncate, (21–)80–100 (–150) × 3–4(–5) μm; hila distinctly thickened, darkened, refractive, 1.5–2.5 μm diam.

Cultural characteristics — Colonies on MEA reaching 45 mm diam after 20 d at 25 °C in the dark; flat with smooth, even margins and moderate aerial mycelium; surface olivaceous-green, reverse dark olivaceous-green.

Specimens examined. IRAN, Guilan Province, Kiashahr, on Sorghum halepense (Poaceae), Aug. 2012, M. Bakhshi (holotype IRAN 16457 F, culture ex-type CCTU 1173 = CBS 136448); Kiashahr, on S. halepense (Poaceae), Aug. 2012, M. Bakhshi, CCTU 1173.2.

Notes — In the individual gene trees (TEF1-α, ACT, CAL and HIS phylogeny), C. sorghicola always resides in a well-supported clade including C. sorghicola and Cercospora sp. A sensu Groenewald et al. (2013). In the combined tree (Fig. 1, part 1), it forms a distinct clade from Cercospora sp. A and these two species are sister taxa. The variation between these two species is based on one nucleotide change in ITS (one insertion in Cercospora sp. A), three nucleotides in TEF1-α (three transitions), two nucleotides in CAL (two transversions), two nucleotides in ACT (one transition and one transversion) and four nucleotide changes in HIS (one transversion and three transitions).

Because sequences for the TEF1-α, ACT, CAL and HIS loci were not available in NCBI for C. sorghi, which has been reported from Sorghum spp., a separate tree that included C. sorghicola, Cercospora sp. A, C. sorghi (GenBank AF291707) and other closely related species was generated using only ITS sequences. In this tree C. sorghicola and C. sorghi reside in different lineages (Fig. 10). Two nucleotide changes at ITS (one transition and one insertion) explain the different position of the isolates used in the current study and C. sorghi. Cercospora sorghicola is also morphologically different from C. sorghi by its longer, wider and multi-septate conidia.

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Fig. 10

Consensus phylogram (50 % majority rule) of 346 trees resulting from a Bayesian analysis of the ITS sequence alignment using MrBayes v. 3.2.1. The tree was rooted to Ramularia endophylla (strain CBS 113265).

Cercospora sp. T — Fig. 11

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Fig. 11

Cercospora sp. T (CBS 136125). a. b. Leaf spots; c. intraepidermal caespituli; d. substomatal caespituli; e. fasciculate conidiophores; f–h. conidia. — Scale bars = 10 μm.

Description in planta — Leaf spots amphigenous, subcircular to irregular, 5–12 mm diam, grey-brown with indefinite margins. Mycelium internal. Caespituli amphigenous, brown. Conidiophores aggregated in loose fascicles (2–8), arising from a weakly developed, intraepidermal and substomatal, dark brown stroma, up to 25 μm diam; conidiophores brown to dark brown, 5–14-septate, straight to geniculate-sinuous due to sympodial proliferation, simple, unbranched, thick-walled, uniform in width, (95–)152–175(–215) × 3.5–5 μm. Conidiogenous cells intercalary and terminal, proliferating sympodially, multi-local; loci thickened, darkened, protuberant, apical or formed on shoulders caused by geniculation, 1.5–3 μm diam. Conidia solitary, hyaline, filiform to acicular, straight to slightly curved, with truncate base and acute to subobtuse apices, (72–)93–115(–180) × (2–)3–4 μm, (7–)10–14(–20)-septate.

Cultural characteristics — Colonies on MEA reaching 65 mm diam after 20 d at 25 °C in the dark; smooth, flat, with even margins and moderate aerial mycelium; surface smoke-grey; reverse iron-grey.

Specimens examined. IRAN, Guilan Province, Rasht, on leaves of Coreopsis sp. (Asteraceae), June 2012, M. Bakhshi, CCTU 1148 = CBS 136125; Rasht, on leaves of Coreopsis sp. (Asteraceae), June 2012, M. Bakhshi, CCTU 1148.2.

Notes — For phylogeny, see the notes under C. iranica. Two species of Cercospora, including C. bidentis and C. coreopsidis, have been reported from Coreopsis spp. Cercospora sp. T is morphologically distinct from C. bidentis by lacking or having small stroma, loose fascicles and dark brown conidiophores. According to its independent phylogenetic position (Fig. 1, part 1), Cercospora sp. T probably represents a host-specific species. Furthermore, Cercospora sp. T and C. cf. coreopsidis (tentative name for an examined and sequenced Korean sample of C. coreopsidis sensu Shin & Kim 2001, see Groenewald et al. 2013), which are both host-specific to Coreopsis spp., are phylogenetically distinct. We presently do not have phylogenetic data from North American material on Coreopsis, which would fix the application of the name C. coreopsidis. The relationship between Cercospora sp. T on Coreopsis from Iran and C. cf. coreopsidis on Coreopsis from Korea needs resolution.