Cercospora phaseoli-lunati U.Braun & Crous, Mycotaxon 92: 396. 2005.

Meswaet, Yalemwork, Mangelsdorff, Ralph, Yorou, Nourou S. & Piepenbring, Meike, 2021, Unravelling unexplored diversity of cercosporoid fungi (Mycosphaerellaceae, Mycosphaerellales, Ascomycota) in tropical Africa, MycoKeys 81, pp. 69-138 : 69

Cercospora phaseoli-lunati U.Braun & Crous, Mycotaxon 92: 396. 2005. MycoBank No: 500171 Figs 2F , 8

Type.

USA. Alabama: Tuskegee , on Phaseolus lunatus ( Fabaceae ), 5 Jul 1897, G.W. Carver 290 (Holotype NY, n.v.) .

Description.

Leaf spots amphigenous, subcircular to irregularly angular, 2.5-8(-12) mm diam., more or less limited by veins, whitish grey to greyish brown, with a narrow to wide dark brown margin on the adaxial surface, less conspicuous on the abaxial surface. Caespituli amphigenous, mainly epiphyllous, scattered, brown to dark brown. Mycelium internal, indistinct. External hyphae absent. Stromata lacking or formed by few aggregated swollen hyphal cells, immersed in the mesophyll or in substomatal cavities. Conidiophores in small, loose fascicles of up to 6, arising from internal hyphae of small hyphal aggregations, breaking through the adaxial epidermis of the leaves or penetrating through stomatal openings, or solitarily arising through stomatal openings, erect, rarely branched, straight to geniculate or subcylindrical to mostly attenuated towards the tips, conical or irregularly shaped, (18-)21.5-94(-102) × (3.5-)4-5 μm, 1-6-septate, smooth, brown to dark brown. Conidiogenous cells terminal, monoblastic or polyblastic; loci distinct, up to 2.5 μm wide, thickened and darkened. Conidia solitary, narrowly obclavate to subacicular, straight to curved, (16-)19-94(-105.5) × 2.5-3.5 μm, 2-7-septate, hyaline to subhyaline, smooth, apex subacute or acute, base truncate to short obconically truncate, up 2.5 μm wide, hila thickened and darkened.

Specimen examined.

Benin. Borgou: Parakou, c. 386 m a.s.l., 9°20'35"N, 2°36'37"E, on Vigna radiata , 14 Sep 2019, Y. Meswaet and R. Dramani, YMM289 (M-0312651 UNIPAR).

Hosts and distribution.

On Phaseolus lunatus from USA, Alabama, Tuskegee (type locality) ( Braun and Crous 2005). This species is cited here for the first time for Benin. Thereby, it is cited for the first time for West Africa. Vigna radiata is a new host species.

Notes.

Thirteen Cercospora species have previously been recorded on species of Vigna and Phaseolus , namely C. albida Matta & Belliard, C. apii , C. canescens , C. canscorina , C. caracallae , C. kikuchii , C. longispora , C. olivascens , C. phaseoli-lunati , C. phaseolicola U.Braun & Mouch., C. phaseolina Speg., C. vignigena and C. zonata G. Winter ( Farr and Rossman 2021). Among these, C. caracallae and C. phaseoli-lunati are morphologically rather similar to the present collection. C. caracallae , however, differs in causing distinct leaf spots and caespituli, dense fascicules composed of unbranched and wider conidiophores [5-6 μm versus (3.5-)4-5 μm in C. phaseoli-lunati ] and wider conidia (3-5.5 μm versus 2.5-3.5 μm in C. phaseoli-lunati ) with less septa (3-5 versus 2-7 septa) ( Chupp 1954; Spegazzini 1910). Except for the presence of distinct leaf spots and sporulation, the morphology of the present collection from Benin fits well to the original description of C. phaseoli-lunati on Phaseolus lunatus from the USA provided by Braun and Crous (2005). Based on the present phylogenies, it is not possible to distinguish C. phaseoli-lunati from numerous other Cercospora spp.

Figures

Figure 2. Leaf spot symptoms associated with Cercospora spp. A Cercospora beninensis on Crotalaria macrocalyx (YMM 11) B Cercospora aff. canescens on Calopogonium sp. (YMM 07) C Cercospora aff. canescens on Vigna subterranea (YMM 01) D Cercospora fagopyri on Lablab sp. (YMM 23 A) E Cercospora parakouensis on Desmodium tortuosum (YMM 296 A) F Cercospora phaseoli-lunati on Vigna radiata (YMM 289) G Cercospora rhynchophora on Vigna unguiculata (YMM 03 B) H Cercospora tentaculifera on Vigna unguiculata (YMM 75) I Cercospora vignae-subterraneae on Vigna subterranea (YMM 293) J Cercospora zorniicola on Zornia glochidiata (YMM 299). Scale bars: 10 mm (A, C, F, G); 12 mm (B, D, E, H, J); 6 mm (I).

Figure 8. Cercospora phaseoli-lunati on Vigna radiata (YMM 289) A small fascicle of conidiophores B solitary conidiophores C conidia. Scale bars: 12 μm (A); 10 μm (B, C).