Pseudocercospora cruenta (Sacc.) Deighton, Mycol. Pap. 140: 142. 1976

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

Pseudocercospora cruenta (Sacc.) Deighton, Mycol. Pap. 140: 142. 1976 Figs 14E , 18

Basionym.

Cercospora cruenta Sacc., Michelia 2:149 (1880).

Type.

USA. South Carolina: (no further information on the locality), on Phaseolus sp. ( Fabaceae ), (no date), Ravenel 2156 (Holotype: PAD, n.v.) .

For more synonyms see Crous and Braun (2003) or MycoBank.

Description.

Leaf spots amphigenous, subcircular to irregularly angular, (2.5-)4-8.5 mm diam., limited by veins, reddish brown to dark brown, with an indefinite margin. Caespituli amphigenous, denser, darker olivaceous to almost sooty on the abaxial surface of the leaves than on the adaxial side. Mycelium internal and external. External hyphae branched, 2.5-3.5 μm wide, septate, olivaceous brown to brown, smooth. Stromata lacking or small, 8-14 μm diam., immersed in the mesophyll or in substomatal cavities, subcircular to irregular, brown to dark brown. Conidiophores in small, loose, moderately large and dense fascicles formed by up to approx. 10 conidiophores, arising from stromata, breaking through the adaxial epidermis of the leaves or penetrating through stomatal openings, sometimes solitary, arising from external hyphae, straight to sinuous or somewhat geniculate, rarely branched, (12-)15.5-54(-58.5) × (3.5-)4-5 μm [in YMM125 up to 120 µm long], 1-3-septate, smooth, olivaceous brown to brown, paler towards the tips. Conidiogenous cells terminal or subterminal, a conidiophore can be reduced to a single conidiogenous cell; loci 2-2.5 μm wide, not thickened and not darkened. Conidia solitary, narrowly obclavate to subacicular, straight to curved, (30.5-)42-132(-154) × (3-)3.5-4.5(-5) μm, 2-10-septate, olivaceous brown, smooth, apex subacute to rounded and slightly narrower than the rest of the conidiophore, up to 2.5 μm wide, base truncate to obconically truncate, 2-2.5(-3) μm wide, hila not thickened and not darkened.

Specimens examined.

Benin. Borgou: Parakou , c. 353 m a.s.l., 9°20'02"N, 2°38'48"E, on Phaseolus sp., 12 Sep 2019, Y. Meswaet and A. Tabé, YMM288 (M-0312670, UNIPAR) . Benin. Atlantique: Commune of Allada, Sékou, c. 84 m a.s.l., 6°38'18"N, 2°13'09"E, on Vigna unguiculata , 15 August 2017, Y. Meswaet and A. Tabé, YMM125 (M-0312671; UNIPAR) . Benin. Borgou: Parakou, c. 385 m a.s.l., 9°20'34"N, 2°36'39"E, same host, 14 Sep 2019, Y. Meswaet and R. Dramani, YMM03A (M-0312672). Borgou: Parakou , c. 394 m a.s.l., 9°21'25"N, 2°36'45"E, same host, 17 Sep 2019, Y. Meswaet and R. Dramani, YMM294B (M-0312673) . Benin. Borgou: Parakou , c. 363 m a.s.l., 9°20'29"N, 2°37'28"E, same host, 21 Sep 2019, Y. Meswaet and A. Tabé, YMM04 (M-0312674) .

Herbarium specimens examined for comparison.

Pseudocercospora cruenta . On Vigna unguiculata : USA. Mississippi: Starkville, Sep 1888, Tracy S. M. s.n. (BPI 435817 Paratype of Cercospora dolichi Ellis & Everh.); On Phaseolus sp.: USA. South Carolina: Aiken, no date, Ravenel H. W. s.n (BPI 439619 Paratype of C. phaseolorum Cooke). Pseudocercospora stizolobii (Syd. & P. Syd.) Deighton. On Mucuna sp.: Philippines. Los Baños, 6 Apr 1913, Raimundo M. B. 892 (BPI 441666 Holotype of C. stizolobii Syd. & P. Syd.) .

Hosts and distribution.

On Calopogonium sp., Canavalia ensiformis (L.) DC., C. gladiata (Jacq.) DC., C. maritima Thouars, Canavalia sp., Cassia lathyroides L., Cicer arietinum L., Clitoria ternatea L., Dolichos biflorus L., D. lablab L., Dolichos sp., Glycine max , Glycine sp., Lablab niger Medik., L. purpureus (L.) Sweet, Mucuna capitata Wight & Arn., M. deeringiana (Bort) Merr., Phaseolus aconitifolius Jacq., P. adenanthus G. Mey., P. aureus Roxb., P. calcaratus Roxb., P. coccineus L., P. lathyroides L., P. lunatus , P. radiatus L., P. sublobatus Roxb., P. vulgaris , Psophocarpus tetragonolobus (L.) DC., Pueraria sp., Strophostyles helvola (L.) Elliott, Vicia faba L., Vigna antillana (Urb.) Fawc. & Rendle, V. catjang (Burm.f.) Walp., V. cylindrica (L.) Skeels, V. luteola (Jacq.) Benth., V. marina (Burm.) Merr., V. mungo (L.) Hepper, V. repens (L.) Kuntze, V. sesquipedalis (L.) Fruwirth, V. sinensis (L.) Savi ex Hausskn., V. unguiculata (L.) Walp., and further species in other genera of Fabaceae . It is widespread in warmer regions, including Afghanistan, Angola, Argentina, Australia, Azerbaijan, Bangladesh, Barbados, Bolivia, Brazil, Brunei, Cambodia, Canada, China, Colombia, Cuba, Dominican Republic, Egypt, EI Salvador, Ethiopia, Fiji, Ghana, Grenada, Guatemala, Guyana, Haiti, Honduras, Hong Kong, India, Indonesia, Iran, Iraq, Italy, Jamaica, Japan, Korea, Liberia, Malawi, Malaysia, Mauritius, Mexico, Mozambique, Myanmar, Nepal, New Caledonia, Niger, Nigeria, Pakistan, Panama, Papua New Guinea, Peru, Philippines, Puerto Rico, Russia, Rwanda, Saint Lucia, Saint Vincent and the Grenadines, Samoa, Saudi Arabia, Senegal, Sierra Leone, Singapore, Solomon Islands, Somalia, South Africa, Sri Lanka, Sudan, Suriname, Taiwan, Tanzania, Thailand, Togo, Tonga, Trinidad and Tobago, Uganda, USA, Venezuela, Virgin Islands, Zambia, Zimbabwe. ( Saccardo 1886; Mulder and Holliday 1975; Ellis 1976; Yen and Lim 1980; Shin and Kim 2001; Crous and Braun 2003; Farr and Rossman 2021).

Notes.

Except for the presence of external hyphae and mostly slightly shorter conidiophores, the present specimen from Benin is morphologically identical to Ps. cruenta as known by literature ( Chupp 1954; Deighton 1976). This identification is confirmed by results obtained by phylogenetic analyses based on tef1 sequence data (see Suppl. material 4). Ps. cruenta is a well-known pathogen causing leaf spot diseases on species of Vigna and allied genera. It can cause serious yield losses of up to 40% in cowpea ( Sivanesan 1990). Ps. cruenta is cited here for the first time for Benin.

Figures

Figure 14. Leaf spot symptoms associated with cercosporoid fungi A, B Nothopassalora personata on Arachis hypogaea (YMM 49 A) B close-up of lesions with caespituli C Passalora arachidicola on Arachis hypogaea (YMM 49 B) D Pseudocercospora bradburyae on Centrosema pubescens (YMM 275) E Pseudocercospora cruenta on Phaseolus sp. (YMM 288) F, G Pseudocercospora griseola on Phaseolus lunatus (YMM 297 A) G close-up of lesions with sporulation H Pseudocercospora sennicola on Senna occidentalis (YMM 12) I Pseudocercospora tabei on Vigna unguiculata (YMM 220). Scale bars: 15 mm (A, D, E, F, I); 100 μm (B, G); 12 mm (D, H).

Figure 18. Pseudocercospora cruenta on Phaseolus sp. (YMM 288) A fascicle of conidiophores protruding from a stomatal opening B solitary conidiophores C conidia. Scale bars: 15 μm (A, C); 10 μm (B).