FungiMycosphaerellalesMycosphaerellaceaeMeswaetYalemworkMangelsdorffRalphYorouNourou S.PiepenbringMeikeUnravelling unexplored diversity of cercosporoid fungi (Mycosphaerellaceae, Mycosphaerellales, Ascomycota) in tropical AfricaMycoKeys1762021816913810.3897/mycokeys.81.67850ADABD0A0-02FA-540B-BBE9-8BD842C15413 Cercospora vignae-subterraneae 839174 Y.Meswaet, Mangelsdorff, Yorou & M.Piepenbr.sp. nov.Figs 2I, 12Type.

Benin. Borgou: Parakou, c. 394 m a.s.l., 9°21'25"N, 2°36'45"E, on Vigna subterranea (L.) Verdc. (Fabaceae), 17 Sep 2019, Y. Meswaet and R. Dramani, YMM293 (Holotype: M-0312657; Isotype: UNIPAR). Ex holotype sequences.MW834446 (SSU), MW834438 (ITS), MW848618 (tef1).

Etymology.

The epithet vignae-subterraneae refers to the host species, Vigna subterranea.

Diagnosis.

Cercospora vignae-subterraneae differs from all other Cercospora spp. known on Vigna spp. in causing often necrotic leaf spots with a pale to white greyish centre, mostly hypophyllous caespituli, external hyphae, flat conidiogenous loci and shorter conidia [(19–)26.5–100(–110.5) µm].

Description.

Leaf spots amphigenous, circular or subcircular to irregularly angular, 2–6.5 mm diam., often limited by veins, brown to greyish brown, later necrotic with a pale to white greyish centre, surrounded by a darker margin, the outermost ring mostly darker than the inner margins. Caespituli amphigenous, but mostly hypophyllous, greyish brown to dark brown. Mycelium internal and external. External hyphae branched, 2–3(–3.5) μm wide, septate, olivaceous brown to brown, smooth. Stromata lacking or small, immersed in the mesophyll or in substomatal cavities. Conidiophores in small to large, loose to dense fascicles or solitary, arising through stomatal openings or breaking through the epidermis, erect, subcylindrical, sinuous or somewhat geniculate, simple or rarely branched, (28–)35.5–278(–340) × (3.5–)4–5 μm, 2–6-septate, smooth, brown to dark brown with slightly paler tips. Conidiogenous cells terminal, usually monoblastic, rarely polyblastic; loci conspicuous, often flat, (1.5–)2–3 μm wide, darkened and thickened. Conidia solitary, narrowly obclavate to subacicular, straight to curved, (19–)26.5–100(–110.5) × (2.5–)3–4 μm, (2–)3–6-septate, hyaline, smooth, apex subacute or acute, base truncate to short obconically truncate, (1.5–)2–2.5(–3) µm wide, hila thickened and darkened.

Additional specimen examined.

Benin. Alibori: Gogounou, c. 333 m a.s.l., 10°50'35"N, 2°49'42"E, on Vigna subterranea Verdc., 2 Sep 2017, Y. Meswaet and A. Tabé, YMM180 (Paratypes: M-0312658; UNIPAR).

Herbarium specimens examined for comparison.

See Cercospora aff. canescens.

Host and distribution.

On Vigna subterranea (Fabaceae) in Benin.

Notes.

Seven species of Cercospora have previously been recorded on Vigna spp. (Table 4) (Farr and Rossman 2021). However, no species of Cercospora is known to occur on Vigna subterranea (Farr and Rossman 2021), a plant species native to West Africa and cultivated mainly in the warm tropics of sub-Saharan Africa (Hepper 1963). Morphologically, C. vignae-subterraneae is distinct from all seven species of Cercospora mentioned above (Table 4). C. apii differs from C. vignae-subterraneae by paler conidiophores occasionally arising from a developed stroma of up to 50 μm diam. and above all, longer and wider conidia [25–300 × 3–6 μm versus (19–)26.5–100(–110.5) × (2.5–)3–4 μm in C. vignae-subterraneae] that are (0–)3–25(–30)-septate (Hsieh and Goh 1990; Crous and Braun 2003). C. canescens causes different leaf spots and caespituli, paler and shorter conidiophores [20–200 µm versus (28–)35.5–278(–340) μm in C. vignae-subterraneae] as well as longer conidia [25–300 μm versus (19–)26.5–100(–110.5) μm of C. vignae-subterraneae] (Hsieh and Goh 1990). C. canscorina forms well-developed stromata as well as paler and shorter conidiophores [29.8–85 µm versus (28–)35.5–278(–340) μm in C. vignae-subterraneae] with 1–3 septa (Chiddarwar 1959).

C. caracallae has densely fasciculate, unbranched and shorter conidiophores [40–80 µm versus (28–)35.5–278(–340) μm in C. vignae-subterraneae] and slightly shorter conidia [50–75 μm versus (19–)26.5–100(–110.5) μm in C. vignae-subterraneae] (Spegazzini 1910). C. kikuchii has unbranched and shorter conidiophores [45–200 × 3–6.5 µm versus (28–)35.5–278(–340) μm in C. vignae-subterraneae] and larger conidia [50–375 μm versus (19–)26.5–100(–110.5) μm in C. vignae-subterraneae] with up to 22 septa (Hsieh and Goh 1990). C. longispora has unbranched, shorter and narrower conidiophores [5–30 × 1.5–3 µm versus (28–)35.5–278(–340) × (3.5–)4–5 μm in C. vignae-subterraneae] with inconspicuous conidiogenous loci and somewhat longer conidia [75–170 × 2–3.5 µm versus (19–)26.5–100(–110.5) μm in C. vignae-subterraneae] (Chupp 1954). C. vignigena has paler, shorter and wider conidiophores [40–130 × 5–7(–10) µm versus (28–)35.5–278(–340) × (3.5–)4–5 μm in C. vignae-subterraneae] that are 0–3-septate, and wider conidia [(2.5–)4–6(–10) μm versus (2.5–)3–4 μm of C. vignae-subterraneae) (Mulder and Holliday 1975).

In the multi-gene (Fig. 1) and in the ITS phylogeny (see Suppl. material 3), C. vignae-subterraneae forms part of a polytomy with a relatively large genetic distance (branch length) in relation to other sequences considered in the analysis. In the tef1 phylogeny (see Suppl. material 4), it is not possible to distinguish C. vignae-subterraneae from other Cercospora spp. Based on the results of our comparative study, we propose C. vignae-subterraneae as a species new to science.

10.3897/mycokeys.81.67850.figure12E289F5BF-650A-5505-BF4E-E48E06C612EB

Cercospora vignae-subterraneae on Vigna subterranea (YMM293) A fascicle of conidiophores B external hypha penetrating through a stomatal opening C solitary conidiophores arising from external hyphae D conidia. Scale bars: 20 μm (A, B); 12 μm (C); 10 μm (D).

https://binary.pensoft.net/fig/55661010.3897/mycokeys.81.67850.figure2F38DCBF7-0609-5E6F-841D-8B3E011F8547

Leaf spot symptoms associated with Cercospora spp. ACercospora beninensis on Crotalaria macrocalyx (YMM11) BCercospora aff. canescens on Calopogonium sp. (YMM07) CCercospora aff. canescens on Vigna subterranea (YMM01) DCercospora fagopyri on Lablab sp. (YMM23A) ECercospora parakouensis on Desmodium tortuosum (YMM296A) FCercospora phaseoli-lunati on Vigna radiata (YMM289) GCercospora rhynchophora on Vigna unguiculata (YMM03B) HCercospora tentaculifera on Vigna unguiculata (YMM75) ICercospora vignae-subterraneae on Vigna subterranea (YMM293) JCercospora zorniicola on Zornia glochidiata (YMM299). Scale bars: 10 mm (A, C, F, G); 12 mm (B, D, E, H, J); 6 mm (I).

https://binary.pensoft.net/fig/556601

Comparison of Cercospora rhynchophora (YMM03B) on Vigna unguiculata, Cercospora tentaculifera (YMM75) on Vigna unguiculata as well as on Phaseolus vulgaris and C. vignae-subterraneae (YMM293, see below) on Vigna subterranea with Cercospora species known from Vigna spp. based on literature a–f.

Cercospora speciesLeaf spots, colour, sizeStromataConidiophore size (in μm), branching, septa, colourConidium sizes (in μm), septa
Cercospora rhynchophora (YMM03B)Dark brown to reddish brown, (3–)4.5–12.5 mm diam.Well-developed(12.5–)26–160(–200) × (3.5–)4–5(–5.5), branched, 0–7(–9)-septate, dark brown(28–)40–265(–280) × (3–)3.5–4.5(–5), 1–9 distinct septa
C. tentaculifera (YMM75) Almost absentSmall or lacking(32.5–)40–400(–435) × (3–)3.5–4.5(–5), rarely branched, (2–)3–8(–10)-septate, brown to dark brown(29–)38–188(–240) × (2.5–)3–3.5(–4.5), 1–9 septa
C. vignae-subterraneae (YMM293)Brown to reddish brown, 2–6.5 mm diam.Lacking or small(28–)35.5–278(–340) × (3.5–)4–5, rarely branched, 2–6-septate, brown to dark brown(19–)26.5–100(–110.5) × (2.5–)3–4, (2–)3–6 septa
C. apii ab PresentOften small or lacking, occasionally developed, up to 50 μm diam.20–300 × 4–6.5, rarely branched, multi-septate, pale brown, uniform in colour and width25–315 × 3–6, (0–)3–25(–30) septab
C. canescens a 3–15 mmOften small20–200 × 3–6.5, rarely branched, multi-septate, pale to medium dark brown25–300 × 2.5–5.5, indistinctly multi-septate
C. canscorina c Pale brown to brown, 3–6 mmDeveloped29.8–85.0 × 3.4–4.2, 1–3-septate, or rarely non-septate, pale brown31.2–89.9 × 3–3.4, 3–9 septa
C. caracallae d PresentPresent40–80 × 5–6, unbranched,50–75 × 4, 3–5 septa
C. kikuchii a PresentSmall45–200 × 3–6.5, unbranched, multi-septate50–375 × 2.5–5, indistinctly multi-septate
C. longispora e PresentSmall5–30 × 1.5–3, unbranched, multi-septate, scars indistinct or lacking75–170 × 2–3.5, indistinctly multi-septate
C. vignigena f Pale to medium brown, 8–20 mmSmall to well-developed (up to 60 μm diam.)40–130 × 5–7(–10), 0–3-septate(35–)45–70(–150) × (2.5–)4–6(–10), (3–)4–7(–14) septa

aHsieh and Goh (1990), bCrous and Braun (2003), cChiddarwar (1959), dSpegazzini (1910), eChupp (1954), fGroenewald et al. (2013).

10.3897/mycokeys.81.67850.figure1B4CBF32E-655B-556C-91A4-C4795C3123EC

The Bayesian phylogenetic tree inferred from DNA sequence data from the multigene alignment (SSU rDNA, LSU rDNA, ITS and tef1) 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.

https://binary.pensoft.net/fig/55660010.3897/mycokeys.81.67850.suppl3297A415F-671C-5B95-AB6F-6E377F8D6A26

A Bayesian phylogenetic tree inferred from ITS rDNA sequence data of cercosporoid species

phylogenetic

Nodes receiving Bayesian PP ≥ 0.94 are considered as strongly supported and are indicated by thickened branches. Newly described species are denoted in bold and red text, newly reported species are indicated in blue text.

https://binary.pensoft.net/file/556622This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.Yalemwork Meswaet, Ralph Mangelsdorff, Nourou S. Yorou, Meike Piepenbring10.3897/mycokeys.81.67850.suppl4C8014C54-C60C-5700-A5B1-3317BD83A046

A Bayesian phylogenetic tree inferred from tef1 DNA sequence data of cercosporoid species

phylogenetic

Nodes receiving Bayesian PP ≥ 0.94 are considered as strongly supported and are indicated by thickened branches. Newly described species are denoted in bold and red text, newly reported species are indicated in blue text.

https://binary.pensoft.net/file/556623This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.Yalemwork Meswaet, Ralph Mangelsdorff, Nourou S. Yorou, Meike PiepenbringHsiehWHGohTK (1990) Cercospora and Similar Fungi from Taiwan.Maw Chang Book Co, Taipei, 376 pp.CrousPWBraunU (2003) Names Published in Cercospora and Passalora.Centraalbureau voor Schimmelcultures, Utrecht, 571 pp.ChiddarwarP (1959) Contributions to our knowledge of the Cercospora of Bombay State I.Sydowia13: 152–163.SpegazziniC (1910) Mycetes Argentinenses (Series V) Deuteromycetes. Anales del Museo Nacional de Buenos Aires 3: e364.ChuppC (1954) A Monograph of the Fungus Genus Cercospora. Published by the author, Ithaca.GroenewaldJZNakashimaCNishikawaJShinH-DParkJ-HJamaANGroenewaldMBraunUCrousPW (2013) Species concepts in Cercospora: spotting the weeds among the roses.Studies in Mycology75: 115–170. https://doi.org/10.3114/sim0012FarrDFRossmanAY (2021) Fungal Databases, U.S. National Fungus Collections, ARS, USDA. https://nt.ars-grin.gov/fungaldatabases/ [Retrieved January 22, 2021]HepperFN (1963) Plants of the 1957–58 West African expedition: II. The Bambara Groundnut (Voandzeia subterranea) and Kersting’s Groundnut (Kerstingiella geocarpa) wild in West Africa.Kew Bulletin16: 395–407. https://doi.org/10.2307/4114681MulderJLHollidayP (1975) Cercospora canescens. CMI descriptions of phytopathogenic fungi and bacteria 462.