Type.

Taxon classification

Fungi

Mycosphaerellales

Mycosphaerellaceae

Meswaet

Yalemwork

Mangelsdorff

Ralph

Yorou

Nourou S.

Piepenbring

Meike

Unravelling unexplored diversity of cercosporoid fungi (

Mycosphaerellaceae

Mycosphaerellales

Ascomycota

) in tropical Africa

MycoKeys17620218169138

10.3897/mycokeys.81.67850

5CFA5669-325A-5B1F-83BE-0E825609FA0C

Cercospora

tentaculifera

839173

Y.Meswaet, Mangelsdorff, Yorou & M.Piepenbr.

sp. nov.

Figs 2H, 11

Type.

Benin. Borgou: Parakou, c. 372 m a.s.l., 9°21'43"N, 2°36'04"E, on Vigna unguiculata (L.) Walp. (Fabaceae), 02 August 2017, Y. Meswaet, M. Piepenbring, N. S. Yorou and participants of the summer school 2017, YMM75 (Holotype: M-0312655; Isotype: UNIPAR). Ex holotype sequences.MW834448 (SSU), MW834440 (ITS), MW848614 (tef1).

Etymology.

The epithet tentaculifera refers to the ramified and flexible hyphae.

Diagnosis.

Cercospora tentaculifera differs from other Cercospora spp. on Vigna and Phaseolus in causing inconspicuous or no leaf spots, well-developed external hyphae, mainly adaxial caespituli and up to 435 μm long conidiophores that are constricted at the septa.

Description.

Leaf spots almost lacking or pale brown with reddish brown discolorations. Caespituli amphigenous, mostly epiphyllous, scattered, greyish brown to dark brown. Mycelium internal and external. External hyphae branched, 2–3.5(–4) μm wide, septate, olivaceous brown to brown, smooth. Stromata lacking or formed by few substomatal swollen hyphal cells, immersed in the mesophyll or in substomatal cavities. Conidiophores in small, loose fascicles formed by up to approx. 8 conidiophores, breaking through the adaxial epidermis of the leaves or penetrating through stomatal openings, solitary when arising from external hyphae, erect, straight, curved or slightly 1–2 times geniculate, often constricted at septa, rarely branched, (32.5–)40–400(–435) × (3–)3.5–4.5(–5) μm, (2–)3–8(–10)-septate, brown to dark brown. Conidiogenous cells terminal, rarely subterminal, mostly monoblastic or with few conidiogenous loci; loci mainly apical, sometimes located on the shoulders of geniculations, 2–2.5(–3.5) μm wide, thickened and darkened, refractive, often subcircular or rarely flattened. Conidia solitary, acicular to narrowly obclavate, straight to curved, (29–)38–188(–240) × (2.5–)3–3.5(–4.5) μm, 1–9-septate, hyaline, smooth, tip acute, base truncate to short obconically truncate, 2.5–3(–3.5) µm wide, hila thickened and darkened.

Additional specimen examined.

Benin. Borgou: Parakou, agricultural research site of the University of Parakou, c. 360 m a.s.l., 9°20'10"N, 2°38'53"E, on Phaseolus vulgaris, 20 Aug 2017, Y. Meswaet and A. Tabé, YMM130 (Paratypes: M-0312656; UNIPAR).

Herbarium specimens examined for comparison.

See Cercospora aff. canescens.

Hosts and distribution.

Known on Phaseolus vulgaris and Vigna unguiculata (Fabaceae) from Benin.

Notes.

Thirteen Cercospora species have previously been recorded on species of Vigna or Phaseolus (Tables 4, 5).

Among these, C. apii, C. canescens and C. phaseolicola have a morphology similar to the present collections, particularly by relatively long conidiophores (Tables 4, 5). C. apii, however, differs from the present species in causing distinct leaf spots (brown to fairly dark in colour with darker margin), the place of sporulation (caespituli more abundant on the abaxial surface of leaves versus on the adaxial surface of leaves in the case of C. tentaculifera), paler and shorter conidiophores [20–300 μm versus (32.5–)40–400(–435) μm in C. tentaculifera] that are occasionally arising from developed (up to 50 μm diam.) stromata and somewhat longer and wider conidia [25–315 × 3–6 μm versus (29–)38–188(–240) × (2.5–)3–3.5(–4) μm in C. tentaculifera] (Hsieh and Goh 1990). C. canescens differs from C. tentaculifera in causing different leaf spots and sporulation, producing dense fascicles, paler and shorter conidiophores [20–200 µm versus (32.5–)40–400(–435) µm in C. tentaculifera] and somewhat longer conidia [25–300 μm versus (29–)38–188(–240) μm in C. tentaculifera] (Hsieh and Goh 1990). C. phaseolicola differs from C. tentaculifera in causing zonate leaf spots and producing only internal hyphae, hardly geniculate, much longer and wider conidiophores [300–600 × 4–7 µm, occasionally up to 10 μm wide versus (32.5–)40–400(–435) × (3–)3.5–4.5(–5) µm] (Braun et al. 1999).

Table 5.

Comparison of Cercospora tentaculifera (YMM75) on Vigna unguiculata and Phaseolus vulgaris with Cercospora species known from Phaseolus spp. based on literature ^a–g.

Cercospora species	Leaf spots, colour, size	Stromata	Conidiophore size (in μm), branching, septa, colour	Conidium sizes (in μm), septa
C. tentaculifera (YMM75)	Almost absent	Small 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. albida ^a	Almost absent	Small or lacking	10–60 × 3–6, branched, 1–2-septate	(30–)50–90(–125) × (1.5–)2–3.5(–4), 0–6 septa
C. canescens ^b	3–15 mm	Often small	20-200 × 3–6.5, rarely branched, multi-septate, pale to medium dark brown	25–300 × 2.5–5.5, indistinctly multi-septate
C. caracallae ^c	Present	Present	40–80 × 5–6, unbranched	50–75 × 3–4, 3–5 septa
C. kikuchii ^b	Present	Small	45–200 × 3–6.5, unbranched, multi-septate	50–375 × 2.5–5, indistinctly multi-septate
C. olivascens ^d	Present	Small	50–200 × 4–5.5, unbranched, multi-septate	35–150 × 4–5.5, 3–9 septa
C. phaseoli-lunati ^e	Present	Present	20–100 × 2.5–5(–6), usually pluri-septate	(20–)30–100 × 1–3, pluri-septate
C. phaseolicola ^f	Present	Absent	300–600 × 4–7(–10), branched, pluri-septate	50–200 × 3–5, pluri-septate
C. phaseolina ^g	Present	No information	50–80 × 4–5, unbranched	20–45 × 3–3.5, 1–3 septa
C. zonata ^d	Present	Lacking or slightly developed	10–80 × 3–5, mostly 10–40, 0–2-septate, unbranched	40–125 × 2.5–4.5, usually 3septa

^aBraun (1995b), ^bHsieh and Goh (1990), ^cSpegazzini (1910)^dChupp (1954), ^eCrous and Braun (2005), ^fBraun et al. (1999), ^gSpegazzini (1881).

Based on the present phylogenies, it is not possible to distinguish this species from many other Cercospora spp. included in this study. Nevertheless, we propose this species as new to science based on a unique combination of morphological characteristics.

10.3897/mycokeys.81.67850.figure11

E2288F27-AE19-54C4-A0A6-FDC59DBA688C

Figure 11.

Cercospora tentaculifera on Vigna unguiculata (YMM75) A fascicle of conidiophores growing out from a small stroma immersed in the epidermis B external hyphae C solitary conidiophores D conidia. Scale bars: 20 μm (A); 12 μm (B); 15 μm (C, D).

https://binary.pensoft.net/fig/556609

10.3897/mycokeys.81.67850.figure2

F38DCBF7-0609-5E6F-841D-8B3E011F8547

Figure 2.

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

Table 4.

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 species	Leaf spots, colour, size	Stromata	Conidiophore size (in μm), branching, septa, colour	Conidium 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 absent	Small 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	Present	Often 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 width	25–315 × 3–6, (0–)3–25(–30) septa^b
C. canescens ^a	3–15 mm	Often small	20–200 × 3–6.5, rarely branched, multi-septate, pale to medium dark brown	25–300 × 2.5–5.5, indistinctly multi-septate
C. canscorina ^c	Pale brown to brown, 3–6 mm	Developed	29.8–85.0 × 3.4–4.2, 1–3-septate, or rarely non-septate, pale brown	31.2–89.9 × 3–3.4, 3–9 septa
C. caracallae ^d	Present	Present	40–80 × 5–6, unbranched,	50–75 × 4, 3–5 septa
C. kikuchii ^a	Present	Small	45–200 × 3–6.5, unbranched, multi-septate	50–375 × 2.5–5, indistinctly multi-septate
C. longispora ^e	Present	Small	5–30 × 1.5–3, unbranched, multi-septate, scars indistinct or lacking	75–170 × 2–3.5, indistinctly multi-septate
C. vignigena ^f	Pale to medium brown, 8–20 mm	Small 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).

Hsieh

Goh

(1990)

Cercospora

and Similar

Fungi

from Taiwan.Maw Chang Book Co, Taipei, 376 pp.

Crous

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(2003) Names Published in

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and

Passalora

.Centraalbureau voor Schimmelcultures, Utrecht, 571 pp.

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(1959) Contributions to our knowledge of the

Cercospora

of Bombay State I.Sydowia13: 152–163.

Spegazzini

(1910) Mycetes Argentinenses (Series V)

Deuteromycetes

. Anales del Museo Nacional de Buenos Aires 3: e364.

Chupp

(1954) A Monograph of the Fungus Genus

Cercospora

. Published by the author, Ithaca.

Groenewald

Nakashima

Nishikawa

Shin

H-D

Park

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Jama

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(2013) Species concepts in

Cercospora

: spotting the weeds among the roses.Studies in Mycology75: 115–170. https://doi.org/10.3114/sim0012

Braun

(1995b) Miscellaneous notes on phytopathogenic hyphomycetes (II).Mycotaxon55: 223–241.

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(2005) Additions and corrections to names published in

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Mouchacca

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EHC

(1999) Cercosporoid hyphomycetes from New Caledonia and some other South Pacific islands.New Zealand Journal of Botany37: 297–327. https://doi.org/10.1080/0028825X.1999.9512636

Spegazzini

(1881)

Fungi

argentini additis nonnullis brasiliensibus montevideensibusque. Pugillus quartus (Continuacion).Anales de la Sociedad Científica Argentina12: 193–227.