Cercospora cf. canscorina Chidd., Sydowia 13 (1-6): 155. 1959.

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 cf. canscorina Chidd., Sydowia 13 (1-6): 155. 1959. Fig. 5

Type.

India. R. Br. Khandala (Maharashtra), on Canscora diffusa (Vahl) R.Br. ex Roem. & Schult. ( Gentianaceae ), 9 Nov 1956, Chiddarwar 4 (Holotype: IMI 83165 , n.v.; Isotype s: HCIO, BPI, n.v.) .

Description.

Leaf spots amphigenous, subcircular to irregularly angular, 2.5-8 mm diam., brown to reddish brown, with a dark margin. Caespituli amphigenous, greyish brown to brown. Mycelium internal. Stromata lacking or formed by few substomatal aggregated swollen hyphal cells. Conidiophores in small, loose fascicles to moderately large and dense fascicles of up to approx. 22 conidiophores, arising from internal hyphae breaking through the adaxial epidermis of the leaves or penetrating through stomatal openings, sometimes solitary, erect, straight, subcylindrical, 1-2 times geniculate, unbranched, (12-)20.5-68(-72) × (3-)3.5-4.5 μm, 0-6-septate, brown to dark brown. Conidiogenous cells terminal, usually monoblastic, sometimes polyblastic; loci apical or sometimes located on the shoulders of geniculations, 1.5-2.5(-3) μm wide, thickened and darkened. Conidia solitary, acicular to narrowly obclavate, straight to curved, 22-76(-80) × 2.5-3.5 μm, 1-7-septate, hyaline, smooth, tip acute, base truncate to short obconically truncate, 2-3 µm wide, hila thickened and darkened.

Specimens examined.

Benin. Borgou: Parakou , c. 386 m a.s.l., 9°20'35"N, 2°36'37"E, on Vigna sp., 14 Sep 2019, Y. Meswaet and R. Dramani, YMM05 (M-0312646; UNIPAR) .

Hosts and distribution.

On Canscora diffusa ( Gentianaceae ) from Khandala, West India ( Chiddarwar 1959) and on Vigna unguiculata (as Vigna catjang (Burm.f.) Walp.) from India ( Bhat and Pratibha 2010). C. cf. canscorina is reported here for the first time for Benin and for Africa.

Notes.

Seven species of Cercospora have previously been recorded on Vigna spp., namely C. apii , C. canescens , C. canscorina , C. caracallae (Speg.) Vassiljevsky & Karak., C. kikuchii , C. longispora Peck and C. vignigena C. Nakash., Crous, U.Braun & H.D. Shin ( Farr and Rossman 2021). The present species from Benin is morphologically identical to C. canscorina ( Chiddarwar 1959; Bhat and Pratibha 2010) except for narrower conidiophores with (3-)3.5-4.5 μm versus 3-7 μm in C. canscorina as mentioned by Bhat and Pratibha (2010). The original specimen of C. canscorina was not available for morphological examination and no DNA sequence data are currently published for this species. Therefore, a reliable species identification is not possible. The application of the name for the collections from Benin is tentative and must be verified based on sequences derived from the Indian type specimen or similar samples. C. cf. canscorina differs from all species of Cercospora on other members of Fabaceae from Benin by producing unbranched, relatively pale conidiophores and above all, shorter conidiophores [(12-)20.5-68(-72) μm] and conidia [22-76(-80) μm]. Based on the multi-gene tree (Fig. 1 ) it is not possible to distinguish Cercospora cf. canscorina from many other Cercospora spp.

Figures

Figure 1. The Bayesian phylogenetic tree inferred from DNA sequence data from the multigene alignment (SSU rDNA, LSU rDNA, ITS and tef 1) of cercosporoid species. Nodes receiving Bayesian PP ≥ 0.94 or MLBS ≥ 70 % are considered as strongly supported and are indicated by thickened branches. Names of newly described species are written in bold and red. Species newly reported for Benin are indicated by green letters. Names of host plants are written with blue letters.

Figure 5. Cercospora cf. canscorina on Vigna sp. (YMM 05) A fascicle of conidiophores protruding from a stomatal opening B solitary conidiophores C conidia. Scale bars: 15 μm (A); 10 μm (B, C).