Revision of Wenyonia Woodland, 1923 (Cestoda:Caryophyllidea) from catfishes (Siluriformes) in Africa

Bjoern C. Schaeffner • Miloslav Jirku •

Zuheir N. Mahmoud • Tomas Scholz

Received: 30 June 2010 / Accepted: 15 December 2010

� Springer Science+Business Media B.V. 2011

Abstract Tapeworms of the genus Wenyonia

Woodland, 1923 (Caryophyllidea: Caryophyllaei-

dae), parasites of catfishes in Africa, are revised.

This revision is based on material from large-scale

sampling, in the Democratic Republic of the Congo,

Kenya, Senegal and the Sudan between 2006 and

2009, and the examination of all of the type-

specimens available. The following six species are

considered valid and their redescriptions are pro-

vided: Wenyonia virilis Woodland, 1923 (type-

species; new synonym W. kainjii Ukoli, 1972);

W. acuminata Woodland, 1923; W. longicauda

Woodland, 1937; W. minuta Woodland, 1923 (new

synonym W. mcconnelli Ukoli, 1972); W. synodontis

Ukoli, 1972; and W. youdeoweii Ukoli, 1972. A key

to the identification of Wenyonia spp. is provided and

numerous new hosts and geographical records are

reported. A comparative phylogenetic analysis of

partial sequences of the 28S rRNA gene of four

species divided the monophyletic genus into two

lineages, one represented by W. acuminata and

W. minuta and another one composed of W. virilis

and W. youdeoweii.

Introduction

Caryophyllideans occupy a special position among

the Eucestoda because they possess a monozoic body,

i.e. containing only a single set of both male and

female reproductive organs (Mackiewicz, 1994). Six

caryophyllidean genera have been reported from

Africa (Khalil & Polling, 1997). The greatest number

of taxa (eight nominal species) has been allocated to

the endemic African genus Wenyonia Woodland,

1923 (family Caryophyllaeidae). Species of this

genus occur in freshwater catfishes of the genus

Synodontis Cuvier (Siluriformes: Mochokidae)

throughout sub-Saharan Africa and the River Nile

system, and are distinguishable from other caryo-

phyllidean cestodes in their general body morphology

(Fig. 1).

Woodland (1923) established Wenyonia to accom-

modate three new species, namely W. virilis Wood-

land, 1923 (type-species), W. acuminata Woodland,

1923 and W. minuta Woodland, 1923 from the River

Nile in the Sudan. Later, Woodland (1937) described

an additional species, W. longicauda Woodland, 1937,

from Sierra Leone. More recently, Ukoli (1972)

described four additional taxa (W. kainjii Ukoli,

B. C. Schaeffner � M. Jirku � T. Scholz (&)

Institute of Parasitology, Biology Centre of the Academy

of Sciences of the Czech Republic, Branisovska 31,

370 05, Ceske Budejovice, Czech Republic

e-mail: tscholz@paru.cas.cz

B. C. Schaeffner

Veterinary Clinical Centre, The University of Melbourne,

250 Princes Highway, Werribee, Victoria 3030, Australia

Z. N. Mahmoud

Faculty of Science, University of Khartoum,

11115 Khartoum, Sudan

123

Syst Parasitol (2011) 79:83–107

DOI 10.1007/s11230-011-9290-2

Fig. 1 General morphology of Wenyonia spp., showing the body regions proposed by Woodland (1923). Composite line drawing of

W. virilis Woodland, 1923 from Synodontis schall, Lake Turkana, Kenya; ventral view

84 Syst Parasitol (2011) 79:83–107

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1972, W. mcconnelli Ukoli, 1972, W. synodontis Ukoli,

1972 and W. youdeoweii Ukoli, 1972) from the River

Niger in Nigeria and presented a key to the species of

the genus.

Between 2006 and 2009, extensive material of

Wenyonia was collected by the present authors and

their co-workers in the Democratic Republic of the

Congo, Kenya, Senegal and the Sudan. This material

enabled us to critically review the species composi-

tion of the genus and to evaluate the morphological

and genetic variability of specimens from different

hosts and geographical regions. Based on these data

and a study of available type-specimens, it was

possible to revise the genus and to assess the validity

of all nominal species.

Materials and methods

Specimens were collected by the authors from a total

of 253 catfishes comprising eight species of Synodon-

tis [S. acanthomias Boulenger, S. caudovittata Bou-

lenger, S. euptera Boulenger, S. frontosa Vaillant,

S. cf. geledensis Gunther, S. nigrita Valenciennes,

S. schall (Bloch & Schneider) and S. serrata Ruppell].

from the following countries: (i) the Democratic

Republic of the Congo: lower Congo River in Bulu

(5�10S, 14�10E); (ii) Kenya: Lake Turkana – El-Molo

Bay (2�500N, 36�420E), Kalokol (3�330N, 35�530E)

and Todonyang (4�260N, 35�570E); (iii) Sudan: the

River Nile at Khartoum (15�370N, 32�310E), the

White Nile at Kostı (13�110N, 32�400E), the Blue

Nile at Sennar (13�320N, 33�380E) and the Atbarah

River at Khashm el-Girba (14�570N, 35�540E). A few

specimens were also collected in Senegal (Niokolo

Koba National Park (13�040N, 12�580E). Type-spec-

imens of Woodland (1923, 1937), deposited at the

Natural History Museum, London, UK, were studied

by one of us (T.S.) in July, 2008.

Several attempts were made to obtain the types or

voucher specimens of the four Wenyonia spp.

described by Ukoli (1972) from Nigeria. Therefore,

repeated written requests were sent to colleagues of

the author and to heads of departments where type-

specimens are most likely to have been deposited,

since explicit information about the deposition of

specimens is missing in the original description.

However, these attempts were unsuccessful and thus

data from the original description had to be used, and

queries regarding unusual or doubtful morphological

characteristics reported in these descriptions could

not be clarified on the basis of the re-examination of

the original material.

Tapeworms collected by the authors were pro-

cessed as described in previous studies (Scholz et al.,

2009; Oros et al., 2010). Live tapeworms were fixed

with hot formalin (4%) for morphological studies;

posterior parts of selected worms (or entire worms if

sufficient numbers were found) were fixed with pure

EtOH (95–99%) for DNA sequencing. Formalin-

fixed worms were used for staining with Schuberg’s

hydrochloric carmine solution (see Scholz & Hanze-

lova, 1998), histology (12 lm cross-sections stained

with Weigert’s haematoxylin-eosin) and for scanning

electron microscopy (SEM) (de Chambrier et al.,

2008, 2009; Oros et al., 2010).

Line drawings of mounted specimens and histo-

logical sections were made using an Olympus BX51

microscope with a drawing attachment and differen-

tial interference contrast optics. Measurements were

taken with analySIS B v.5.0 software (Olympus

Biosystems) and are all in micrometres unless

otherwise indicated. Number of measurements (n)

and metrical data from the original descriptions (if

available) are in parentheses.

The terminology of the individual body parts of

Wenyonia spp. used in the redescriptions follows

Woodland (1923) with the following modifications: (i)

the scolex extends posteriorly to a well-defined base

[i.e. a narrowing (see Fig. 3H) or a transverse band of

darkly stained cells (if present; see Fig. 1)]; (ii) the

testicular region reaches from the scolex base to the

genital pores or the common genital atrium (see

Fig. 1). The neck portion (if present) represents the

anterior part of the testicular region devoid of testes

and vitelline follicles (in Fig. 2D, the region between

the first and second horizontal line anteriorly); (iii) the

uterine region reaches from the genital pores to the

posteriormost border of the ovarian arms; and (iv)

the postovarian region comprises the posterior part of

the body from the ovarian arms to the posteriormost

extremity (see Fig. 1). This region may contain a

distinct caudal portion lacking internal organs, i.e.

vitelline follicles (see Fig. 1). Egg terminology fol-

lows Conn & Swiderski (2008).

Newly collected specimens have been deposited

in: the Helminthological collection of the Institute of

Parasitology, Biology Centre of the Academy of

Syst Parasitol (2011) 79:83–107 85

123

Sciences of the Czech Republic, Ceske Budejovice,

Czech Republic (acronym IPCAS); the Natural

History Museum, London, UK (BMNH); the Natural

History Museum, Geneva, Switzerland (MHNG); and

the US National Parasite Collection, Beltsville,

Maryland, USA (USNPC).

A total of 34 partial (D1–D3) 28S rDNA sequences

were obtained from specimens collected from seven

sampling localities (Congo – 1, Kenya – 3, Sudan – 3)

and from six host species (Synodontis acanthomias

– 2 samples, S. caudovittata – 3, S. frontosa – 6, S.

cf. geledensis – 1, S. schall – 21 and S. serrata – 1).

Most specimens (21) were collected in the Sudan,

11 in Kenya and 2 in the Democratic Republic of

the Congo.

The genomic DNA was extracted using JET-

QUICK Tissue DNA Spin Kit (GENOMED). PCR

amplifications of partial 28S rDNA were carried out

Fig. 2 Outlines of the body and individual body regions of Wenyonia spp. (ovary indicated in black; caudal portion separated by a

dashed line): A–C, W. virilis (morphological variation within W. virilis populations is documented; note the total shape and relative

proportion of the body and the relative lengths of the testicular region and caudal portion); D, W. acuminata; E, W. minuta; F,

W. longicauda, redrawn from Woodland (1937, Pl. 1, fig. 1); G, W. synodontis, scale-bar not provided; H, W. youdeoweii. Scale-bars:

A–C, 5 mm; D–G, 1 mm

86 Syst Parasitol (2011) 79:83–107

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in 50 ll standard reactions. Primers LSU-5 (Little-

wood et al., 2000) and 1500R (Tkach et al., 1999)

were used for PCR amplification, which was per-

formed with the following conditions: 10 min dena-

turation at 94�C, 35 cycles of 30 s at 94�C, 30 s at

57�C, 1.5 min at 72�C and a 10 min extension hold at

72�C. PCR amplicons were checked on ethidium

bromide stained agarose gel and either purified with

QIAquick Gel Extraction Kit (Qiagen) following the

manufacturer’s instructions or by enzymatic (SAP/

ExI) degradation (see Werle et al., 1994).

The 28S rDNA samples were cycle-sequenced

using BigDyeTM Terminator v.3.1 Ready Sequencing

Kit (Applied Biosystems Inc.) on the ABI 3730XL

DNA analyzer (Applied Biosystems Inc.). Besides

the amplification primers a variety of internal

sequencing primers (300F, 400R and 900F; Little-

wood et al., 2000, and Littlewood & Olson, 2001)

were used. The contiguous sequences were assembled

and edited with Seqman II v.5.05 (DNASTAR).

Newly obtained sequences have been deposited in the

GenBank database under accession numbers HQ848489-

HQ848522.

Based on existing data (Olson et al., 2008) and

preliminary analyses (data not shown), Monoboth-

rioides chalmersius (Woodland, 1924) (Lytocestidae)

from Clarias gariepinus (Burchell) in Africa (Gen-

Bank Accession No. EF095253) served as an out-

group. The 28S rDNA sequences were aligned using

the ClustalW algorithm implemented in the Mega4

software (www.megasoftware.net) using the default

settings and penalties. The aligned sequences were

approved by eye in MacClade 4.08 (Maddison &

Maddison, 2005) and fragments concatenated. Posi-

tions which were ambiguously aligned or contained

gaps were excluded from the analysis.

The 28S rDNA sequences were then analysed

with the Bayesian inference (BI) algorithm using

MrBayes v.3.0.b4 (Huelsenbeck & Ronquist, 2001).

Modeltest v.3.7 (Posada & Crandall, 1998) esti-

mated the GTR ? C8 ? I model of evolution

according to the Akaike Information Criterion

(AIC). Likelihood settings were as follows:

nst = 6, rates = invgamma, ngammacat = 4. Nodal

support was estimated as posterior probabilities (PP)

with four simultaneous MCMC chains, estimated

over one million generations and with every 100-th

generation saved. A total of 13,000 generations were

discarded as ‘burnin’.

Results

Evaluation of the newly collected material, supple-

mented by a study of all of the type-specimens

available, has revealed that Wenyonia Woodland,

1923 contains the six valid species redescribed

below. On the basis of these descriptions, a revised

generic diagnosis of Wenyonia is provided.

Wenyonia Woodland, 1923

Diagnosis

Caryophyllidea, Caryophyllaeidae. Monozoic; body

monopleuroid; body surface covered by filiform

microtriches. Inner longitudinal musculature well

developed, variable in appearance between body

regions and species, external to testes and vitelline

follicles. Excretory system well developed, with main

lateral canals and smaller, medially anastomosed

canals; numbers of canals decrease posteriorly; canals

open into excretory bladder near posterior extremity.

Scolex variable in shape, usually rugomonobothri-

ate (sensu Mackiewicz, 1994, and Ibraheem &

Mackiewicz, 2006), i.e. with deep and/or shallow

longitudinal furrows and apical introversion; in most

species with transverse band of darkly stained cells

demarcating base. Neck portion distinct or absent.

Testes medullary, reach back to level of cirrus-sac or

sligthly more posterior, vas deferens or anterior

uterine coils, which they may embrace, mostly not

intermixed with vitelline follicles, in single or several

layers, well separated to closely packed; anteriormost

testes begin anterior to, posterior to or at same level

as first vitelline follicles. Vas deferens median,

anterior to cirrus-sac, mostly surrounded by testes.

Cirrus-sac well developed, oval, contains ejaculatory

duct and cirrus. External seminal vesicle absent.

Genital pores in anterior part of body, open into

shallow genital atrium or separately on ventral

surface. Male pore usually larger and wider than

female pore. Ovary medullary, H-shaped, with pos-

terior arms sometimes bent inwards but never uniting.

Vagina tubular, usually sinuous, joins with uterus to

form short uterovaginal canal. Seminal receptacle

present. Vitelline follicles extensive, medullary, may

reach to posterior extremity; pre-ovarian follicles in

distinct lateral bands, present or absent alongside

ovarian arms; postovarian follicles present as lateral

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bands with or without medially dispersed follicles.

Uterus forms numerous loops anterior to ovary but

never extends anterior to cirrus-sac; uterine glands

absent. Eggs operculate, thick-walled, with rough or

slightly pitted surface, may contain fully-formed

oncosphere in utero. Parasites of freshwater catfishes

(Synodontis) in Africa.

Type-species: W. virilis Woodland, 1923.

Other species: W. acuminata Woodland, 1923;

W. longicauda Woodland, 1937; W. minuta Wood-

land, 1923; W. synodontis Ukoli, 1972; and W.

youdeoweii Ukoli, 1972.

Wenyonia virilis Woodland, 1923

Syns Caryophyllaeus niloticus Kulmatycki, 1928;

Wenyonia kainjii Ukoli, 1972 (new synonym)

Type-host: Synodontis schall (Bloch & Schneider).

Additional hosts: S. batensoda Ruppell, S. budgetti

Boulenger, S. caudovittata Boulenger (new host),

S. clarias (L.), S. euptera Boulenger (new host),

S. frontosa Vaillant (new host), S. gambiensis Gun-

ther (new host), S. cf. geledensis Gunther (new host),

S. nigrita Valenciennes (new host), S. ocellifer

Boulenger, S. serrata Ruppell, S. sorex Gunther

(new host).

Type-locality: River Nile at Khartoum, Sudan.

Geographical distribution: Africa: basins of the Niger

(Nigeria), Nile (Egypt, Sudan), Omo (Kenya – Lake

Turkana) and Gambia (Senegal) rivers.

Site of infection: Small intestine.

Prevalence of infection: Kenya: Loiyangalani:

53% (n = 17; S. schall), 100% (n = 1; S. cf.

geledensis); Todonyang: 50% (n = 12; S. frontosa);

9% (n = 22; S. schall). Sudan: Girba: 25% (n = 4;

S. euptera); 26% (n = 27; S. frontosa); 20% (n = 5; S.

nigrita); 12% (n = 17; S. schall); Kostı: 50% (n = 4;

S. caudovittata); 25% (n = 4; S. nigrita); 31%

(n = 26; S. schall); Sennar: 21% (n = 14; S. schall).

Precise data on intensity of infection not available,

since high worm burdens were found in most localities

with many small, immature specimens.

Type-specimens: Syntypes in BMNH.

References: Woodland (1923, 1924, 1926),

Kulmatycki (1928), Khalil (1969), Ukoli (1972),

Banhawy et al. (1975, 1979), Fahmy et al. (1976),

El-Naffar et al. (1983), Imam et al. (1991), Garo et al.

(2000), Al-Bassel (2003), Ibraheem & Mackiewicz

(2006), Gamil (2008), Miquel et al. (2008), Swiderski

et al. (2009).

Material studied: 11 syntypes from Synodontis schall,

River Nile, Khartoum, Sudan, 1913 (BMNH Nos

1923.12.4.1, 1961.3.14.81.1–3, 84, 92, 95, 97, 103,

107, 109); one voucher specimen from S. gambiensis

and one voucher specimen from S. sorex, River

Niger, Kainji Dam, Nigeria, collected by J.B.E.

Awachie (BMNH Nos 1970.8.24.32,33); three spec-

imens from S. cf. geledensis and 40 specimens from

S. schall, Lake Turkana, El-Molo Bay, Kenya, 2007,

2008, collected by M. Jirku; 23 specimens from S.

frontosa, Lake Turkana, Todonyang, Kenya, 2008,

collected by M. Jirku & M. Oros; two specimens

from S. batensoda, one specimen from S. nigrita and

seven specimens from S. ocellifer, Niokolo Koba

National Park, Senegal, 2006, collected by B. Koub-

kova and colleagues; two specimens from S. euptera,

21 specimens from S. frontosa, three specimens from

S. nigrita and two specimens from S. schall, Atbarah

River, Girba, Sudan, 2008, collected by T. Scholz &

A. de Chambrier; three specimens from S. caudovit-

tata, one specimen from S. nigrita and 29 specimens

from S. schall, White Nile River, Kostı, Sudan, 2008,

collected by T. Scholz & A. de Chambrier; 13

specimens from S. schall, Blue Nile River, Sennar,

Sudan, 2008, collected by T. Scholz & A. de Chambrier

(BMNH 2010.8.10.14–17; IPCAS C-503; MHNG

70455, 72931–72934; USNPC 103418–103421).

Redescription (Figs. 1, 2A–C, 3A,B, 4A–I, 5A,B,

6A,B)

[Based on 126 hot formalin-fixed specimens from

S. batensoda, S. caudovittata, S. euptera, S. frontosa,

S. cf. geledensis, S. nigrita, S. ocellifer and S. schall.]

Body shape and proportions of body parts highly

variable; body 6.7–40.2 (n = 63; 11.0–52.5) 9

0.7–3.5 (n = 75) mm, with maximum width at scolex

or uterine region. Surface uniformly covered with

filiform microtriches (Fig. 4H).

Scolex very short, 0.8–2.6 (n = 74) 9 0.7–3.5

(n = 75) mm, representing 3–14 (n = 64)% of body

length. Testicular region relatively short and narrow,

0.4–5.9 (n = 76) 9 0.6–1.9 (n = 77) mm, i.e. 11–19

(n = 64)% of total length, decreases in width towards

cirrus-sac. Uterine region occupies roughly about

quarter of body, i.e. 16–32 (n = 64)% of body length,

1.8–10.4 (n = 74) mm 9 0.7–2.5 (n = 77) mm,

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about equal in width or with maximum width at mid-

level. Postovarian region very long, 3.0–25.9

(n = 66) mm long, i.e. 24–79 (n = 64)% of body

length, mostly curled (Fig. 1), tapered to narrow or

almost bluntly ending tip (Fig. 1).

Inner longitudinal musculature formed by wide

band of massive bundles of muscle fibres, especially

in testicular region (Fig. 5A). Main longitudinal

excretory canals lateral, 2–7 in number, external to,

or within, vitelline field, increase in width towards

uterine region, decrease in number posteriorly.

Excretory bladder thick-walled, elongate to almost

round, near posterior extremity; excretory pore

terminal.

Scolex conical to sagittate (Fig. 3A,B), rugomono-

bothriate, i.e. with 16–30 deep longitudinal furrows

and apical introversion, from narrow to very wide,

with maximum width at mid-level or almost at base,

always wider than testicular region (Fig. 4A–E); base

with transverse band of darkly stained cells

(Fig. 3A,B).

Testes medullary, subspherical, 64–176 9 54–124

(n = 290), 85–410 (n = 72) in number, in single or

several layers. Anteriormost testes located 0–49

(n = 70) posterior to scolex base, reach posteriorly

to 2–8 anteriormost uterine coils, surround cirrus-sac.

Cirrus-sac oval, 170–720 9 120–360 (n = 76). Male

genital pore 27–73 9 43–124 (n = 77), longer and

wider than separate female pore (Fig. 4I). Common

genital atrium absent.

Ovary follicular, bilobed, H-shaped; ovarian arms

from long and narrow to short and wide, 0.5–2.4

Fig. 3 Scolex morphology of Wenyonia spp. A, B, W. virilis Woodland, 1923; C, W. acuminata Woodland, 1923; D, W. longicaudaWoodland, 1937 (anterior part of the syntype – BMNH No. 1961.3.14.131); E, F, W. minuta Woodland, 1923; G, H, W. youdeoweiiUkoli, 1972. Note scolex shape variability in A, B and E, F. Scale-bars: 500 lm

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(n = 147) mm long; anterior arms reach along 3–8

posteriormost uterine coils anterior to ovarian isth-

mus. Vagina tubular, slightly sinuous, 20–59

(n = 131) wide. Seminal receptacle small, subspher-

ical, 100–167 9 57–95 (n = 10), anterodorsal to

ovarian isthmus.

Vitelline follicles medullary, well separated from

testes and much smaller, 28–102 9 17–66 (n = 870),

increase in size posteriorly, begin 7–106 (n = 70)

posterior to scolex base and form single pair of lateral

bands; postovarian follicles form 2 lateral, narrow,

often interrupted bands of few follicles and very wide

central band, reaching 0.1–15.2 (n = 65) mm from

posteriormost extremity.

Uterus tubular, forms numerous, slender coils.

Uterine field elongate, narrow, with maximum width

Fig. 4 Scanning electron micrographs of: A–I, Wenyonia virilis Woodland, 1923; J–L, W. minuta Woodland, 1923; M, N, W.youdeoweii Ukoli, 1972. A–E & J–N, Scoleces; F, G, Opercular pole of eggs (note operculum and reticulate structure of the surface);

H, Filiform microtriches from the scolex; I, Separate gonopores. Abbreviations: fp, female genital pore; mp, male genital pore; op,

operculum. Scale-bars: A–E, J–N, 300 lm; F,I, 10 lm; G, 5 lm; H, 1 lm

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at mid-level or more anteriorly, 1.5–9.4 (n =

76) 9 0.3–1.6 (n = 77) mm. Female genital pore

19–48 9 30–81 (n = 77), opens 10–62 (n = 77)

posterior to male pore (Fig. 4I).

Eggs oval, operculate (Figs. 4F, 6A,B), with

surface covered with reticulate structures (Fig. 4G),

47–51 9 26–27 (n = 290), embryonated, i.e. con-

taining fully-formed oncosphere with 6 embryonic

hooks (Fig. 6B).

Remarks

Examination of a large number of specimens of

Wenyonia virilis from several Synodontis spp. in four

river basins of northeastern, eastern and western Africa

has shown the morphological variability of this

species, especially in the shape of the body, propor-

tions and size of individual body regions (Fig. 2A–C),

shape of the scolex (Figs. 3A,B, 4A–E) and distribution

Fig. 5 Cross-sections of Wenyonia spp. in the testicular (A, C, E, G), uterine (B, D, F) and postovarian regions (H). A, B, W. virilisWoodland, 1923; C, D, W. minuta Woodland, 1923; E, F, H, W. longicauda Woodland, 1937; G, W. youdeoweii Ukoli, 1972.

Abbreviations: c, cirrus; cs, cirrus-sac; ex, excretory canal; ilm, inner longitudinal musculature; n, nerve; ov, ovary; t, testis; ut,

uterus; vag, vagina; vd, vas deferens; vf, vitelline follicle. Scale-bars: A–D, 300 lm; E,H, 500 lm; F, 250 lm; G, 200 lm

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of the vitelline follicles in the postovarian region.

However, the conspecificity of all specimens, which

invariably possessed a rugomonobothriate scolex

which was always wider than the testicular region,

was confirmed by molecular data, i.e. by the presence

of a single genotype in all 22 analysed specimens.

Ukoli (1972) provided erroneous information on

W. virilis in his key, because: (i) the combined length

of the testicular and uterine regions is in fact greater

than a third of the total body length, not less than a

third as claimed in the key; (ii) the testicular region

represents less than 20% of the body length in all

specimens observed, rather than more than a fifth;

(iii) the pre-ovarian vitelline follicles form only one

pair of longitudinal rows, instead of multiple bands as

reported by Ukoli (1972); and (iv) the postovarian

vitelline follicles vary in their posterior extent from

half the length of the postovarian region to almost the

end of the body, rather than invariably finishing at the

posterior end of the body.

Wenyonia virilis was originally described from

S. schall at Khartoum, Sudan (Woodland, 1923).

Kulmatycki (1928) reported this species, as Caryo-

phyllaeus niloticus Kulmatycki, 1928, from the same

host at Cairo, Egypt and at Omdurman (North

Khartoum), Sudan. Numerous records of W. virilis

exist, mainly from Egypt (Garo et al., 2000;

Al-Bassel, 2003; Ibraheem & Mackiewicz, 2006).

This tapeworm was previously found in six species of

Synodontis, but as many as seven new definitive hosts

are reported in the present study.

Ukoli (1972) described W. kainjii Ukoli, 1972

based on four specimens from S. nigrita in the River

Niger at Shagunu, Nigeria. However, almost all of the

specific characteristics of W. kainjii are identical

with, or similar to, those of W. virilis, as described by

Woodland (1923) and redescribed in this paper,

including the shape of the scolex, which is the most

typical characteristic of the latter species, and the

arrangement of the testes and vitelline follicles.

Metrical data of W. kainjii provided by Ukoli

(1972) also correspond with those of W. virilis, such

as the proportions, lengths and widths of different

body regions, cirrus-sac, testes and vitelline follicles,

and the length of the ovarian arms. In fact, W. virilis

and W. kainjii allegedly differ from each other in just

one characteristic, the validity of which is question-

able. According to Ukoli (1972), the eggs of W.

kainjii measure 63–83 9 44–57 lm, whereas those

of W. virilis are only 29–54 9 15–23 lm. However,

Ukoli (1972) reported the sizes of the eggs of all

Wenyonia spp. to be 1.5–2 times larger than those of

the species studied by Woodland (1923, 1937) and

the present authors. Accordingly, W. kainjii, which

has never been found since its original description in

1972, is here synonymised with W. virilis.

In Kenya and the Sudan, the type-host (S. schall)

was the most heavily infected (45 fish infected of 121

examined, i.e. a prevalence of 37%). Findings of W.

virilis in Kenya and Senegal represent new geo-

graphical records of this parasite, which has the

largest known distribution of all Wenyonia spp.

Wenyonia acuminata Woodland, 1923

Type-host: Synodontis membranacea (Geoffroy

Saint-Hilaire).

Additional hosts: S. acanthomias Boulenger (new

host), S. clarias (L.).

Type-locality: River Nile at Khartoum, Sudan.

Geographical distribution: Africa: basins of the

Congo (Democratic Republic of the Congo), Epe

(Nigeria) and Nile (Sudan) rivers.

Site of infection: Small intestine.

Prevalence and intensity of infection: Democratic

Republic of the Congo: prevalence 50% and intensity

1–3 (mean 2) (n = 4; S. acanthomias).

Fig. 6 Polylecithal eggs of Wenyonia virilis Woodland, 1923:

A, Unripe egg from the distal part of uterus; B, Embryonated,

ripe egg with fully-formed hexacanth. Abbreviations: hex,

hexacanth; bl, blastomere; op, operculum; sh, shell; vit,

vitellocyte. Scale-bar: 10 lm

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Type-specimens: Syntypes in BMNH.

References: Woodland (1923, 1926), Akinsanya et al.

(2008).

Material studied: Five syntypes from S. membrana-

cea, Nile River, Khartoum, Sudan, 1913 (BMNH

Nos 1961.3.14.48–52); eight voucher specimens from

S. clarias, Epe River and Lekki Lagoon, Lagos

State, Nigeria, 2003 (BMNH Nos 2002.11.1.10–14;

2004.2.18.31–33); three specimens from S. acantho-

mias, Congo River, Bulu, Democratic Republic of

the Congo, 2008, collected by M. Jirku (BMNH

2010.8.10.18; IPCAS C-570).

Redescription (Figs. 2D, 3C, 7A, 9A)

[Based on 1 complete, 1 incomplete and 1 immature

hot formalin-fixed specimens from S. acanthomias.]

Body elongate, nematodiform, slender, 23.7 (n = 1;

17.5–34.5) 9 0.9 (n = 1; 1.2–1.5) mm, almost equal

in width throughout body length, with maximum

width at testicular region and slight constriction at

level of cirrus-sac.

Scolex very short, 0.7–0.8 (n = 3; 2.5–4.0) mm

long, representing 4% (n = 1; 13%) of total body

length. Testicular region relatively long, 8.8 (n = 2;

7.5–11.0) mm 9 0.8–0.9 (n = 2) mm, i.e. 37%

(n = 1; 36%) of body length, narrowing at level of

cirrus-sac. Uterine region 5.5–6.3 (n = 2; 5.0–13.5)

mm 9 0.5–0.7 (n = 2) mm, i.e. 27% (n = 1; 32%)

of body length. Postovarian region 7.7 (n = 1; 2.5–

6.5) mm long, i.e. 32% (n = 1; 19%) of body length,

tapering posteriorly (Figs. 2D, 7A).

Inner longitudinal musculature formed by isolated

muscle fibres. Excretory canals cortical, very narrow

and anastomosed, thin-walled in scolex, extend

posteriorly usually as 3 to 4 narrow lateral canals

on each side, connected by centrally anastomosed

canals. Excretory bladder thick-walled, elongate, near

posterior extremity.

Scolex subconical, almost digitiform sensu Mack-

iewicz (1994, fig. 5.8), usually with 6 shallow

longitudinal furrows (3 on each side; Fig. 3C); apical

introversion absent; scolex 0.5–0.6 (n = 2) mm wide

at base. Narrow transverse band of similar cells

delimits posterior margin of scolex (Fig. 3C). Scolex

as wide as neck region. Neck 1.3–1.5 (n = 2) mm

long (Fig. 2D).

Testes medullary, subspherical, 400–470 (n = 2)

in number, 65–88 (n = 10; 116) 9 47–62 (n = 10;

66); anteriormost testes located 1.3–1.6 (n = 2; 1.6–

4.5) mm posterior to scolex, not reaching posteriorly

to anterior margin of cirrus-sac (Figs. 7A, 9A).

Cirrus-sac oval, 420 9 280–300 (n = 2), occupying

about third of total body width (Figs. 7A, 9A). Male

genital pore 36–40 9 87–91 (n = 2), opens into

shallow common genital atrium. Atrium transversely

oval to subspherical (Fig. 9A), 49–72 9 91–92

(n = 2).

Ovary follicular, bilobed, H-shaped, 1.8–2.0

(n = 2) mm in total length; anterior arms longer

and narrower than posterior arms, alongside 10–12

posteriormost uterine coils (Fig. 7A). Vagina tubular,

slightly sinuous, 20–29 (n = 2; 21–36) wide. Sem-

inal receptacle small, subspherical, anterodorsal to

isthmus, 85–90 9 65–70 (n = 2).

Vitelline follicles medullary, small, 21–37 9 14–

23 (n = 30; 43 in diameter), forming single longitu-

dinal band on each side of body in testicular and

postovarian regions; several follicles present along-

side cirrus-sac and ovarian arms. Bands well sepa-

rated from testes, begin 1.5 (n = 1; 1.5–5.0) mm

posterior to scolex base; follicles almost absent

medially in postovarian region; lateral bands unite

near posterior extremity, end 0.50 (n = 1; 0.25) mm

from posterior extremity (Fig. 7A).

Uterus coiled; uterine loops equal in width; uterine

field narrow and relatively short, 5.5–5.6 (n = 2) 9

0.4–0.5 (n = 2) mm. Female genital pore 22–30 9

45–62 (n = 2).

Eggs oval, operculate, 33–43 (n = 10; 35–37) 9

18–23 (n = 10; 22–26), with slightly pitted surface.

Remarks

The specimens from the Congo were identified as

Wenyonia acuminata because they possess: (i) a

nematodiform shape, i.e. a long, narrow body with

almost the same width throughout its entire length,

insignificantly widened in the testicular region; (ii)

vitelline follicles arranged in two longitudinal rows;

(iii) the combined lengths of the testicular and uterine

regions greater than a third of the total body length; and

(iv) both these regions roughly equal in length (see

Woodland, 1923). In addition, only a few differences

were observed between the measurements of the types

of W. acuminata and newly collected material.

The postovarian region in the present material is

somewhat longer, about a third of the total body

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length, than in the type-specimens from the Sudan

and voucher specimens from Nigeria, in which the

postovarian region represents only about 10–20%.

Furthermore, this region is tapered towards the

posterior extremity in the present material, but

Woodland (1923) reported the posterior end to be

stumpy and bluntly pointed.

According to Woodland (1923), the scolex is not

delimited from the rest of the body, i.e. a transverse

band at its base is missing, and the scolex was

considered to end at the position where the anterior-

most testes and vitelline follicles commence (see

fig. 17 in Woodland, 1923). Instead, the scoleces of

the three specimens of W. acuminata from the Congo

invariably possess a well-defined base characterised

by a conspicuous transverse band of darkly stained

(chromophilic) cells, thus delimiting the scolex to a

relatively very short region compared to Woodland’s

data (4 vs 13% of body length).

Another slight difference from the original

description of W. acuminata is that the scoleces of

the specimens from Congo were not ‘‘tapering to a

fine point’’, as described by Woodland (1923), but

were rather digitiform with a rounded anterior

extremity. Furthermore, the scoleces of the Congo

material possess shallow longitudinal furrows

(Figs. 3C, 7A), whereas the type- and voucher

specimens were not creased longitudinally. Wood-

land (1923) also stated that the vitelline follicles

begin posterior to the testes. In fact, the anterior

extent of the vitelline follicles of all of the observed

specimens is variable, and the anteriormost vitelline

follicles may also begin anterior to the testes

(Fig. 7A).

Despite the above-mentioned discrepancies

between the newly-collected specimens and those of

the original description, we consider them to be

conspecific based on the unique characteristics out-

lined above. All of the above-mentioned differences

might represent intraspecific variability within W.

acuminata populations from different hosts and

geographical regions. Some variations in the shape

of the scolex and the posterior region may also be

accounted for by differences in fixation (it seems

that Woodland’s specimens did not have a natural

shape).

Woodland (1923) described the eggs of this

species to be covered with minute spinelets, but the

surface of the eggs of specimens from the Congo

appears to be pitted rather than spiny. Unfortunately,

uncollapsed eggs suitable for SEM observation were

not available to provide reliable information on the

surface structure.

This species was originally described from Syn-

odontis membranacea in the Sudan. Akinsanya et al.

(2008) recorded it from S. clarias in Nigeria, and

Akinsanya & Otubanjo (2006) also reported it from

Clarias gariepinus (Burchell, 1822). However, the

latter finding is considered to be doubtful, because C.

gariepinus has never been reported to harbour

specimens of Wenyonia by other authors and voucher

specimens were not available. It is possible that

Monobothrioides chalmersius (Woodland, 1924), a

common parasite of this catfish, was misidentified as

W. acuminata.

Synodontis acanthomias represents a new defini-

tive host and the Democratic Republic of the Congo

is the third country in which the parasite has been

reported, but W. acuminata was not found in any of

155 specimens of nine species of Synodontis, includ-

ing four S. membranacea, examined in the Sudan

during 2006 and 2008. This catfish and S. clarias

occur mainly in the River Niger and the delta of the

River Nile, whereas S. acanthomias is reported only

from the Congo River basin (Froese & Pauly, 2010).

Wenyonia longicauda Woodland, 1937

Type- and only host: Synodontis gambiensis Gunther.

Type-locality: Not mentioned explicitly; either the

River Teye at Mano or the River Waanje near

Pujehun, Sierra Leone.

Geographical distribution: Africa: basins of the

Rivers Teye and Waanje (Sierra Leone).

Site of infection: Intestine.

Type-specimens: Syntypes in BMNH.

Reference: Woodland (1937).

Material studied: Seven syntypes from Synodontis

gambiensis, Rivers Teye and Waanje, at Mano and

Pujehun, Sierra Leone, 1937 (BMNH Nos 1961.3.

14.130, 131, 134, 136, 138, 140/1–2).

Fig. 7 A, Wenyonia acuminata Woodland, 1923 from Syn-odontis acanthomias, River Congo, Democratic Republic of

the Congo; B, W. youdeoweii Ukoli, 1972 from S. serrata,

River Nile, Sudan. Entire worm, ventral (A) and dorsal (B)

views. Scale-bars: 1 mm

b

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Redescription (Figs. 2F, 3D, 5E,F,H)

[Based on original description and type-material.]

Body long, slender, up to 23.5 (n = 1) mm long by

2.1 (n = 1) mm wide; surface covered with longitu-

dinal and transverse grooves.

Scolex very short, 0.9–1.0 (n = 3) 9 1.1–1.3

(n = 2) mm, representing 4% of total body length.

Testicular region 2.4 (n = 1) mm long, i.e. 10% of

total body length, 1.3–1.9 (n = 2) mm wide, almost

same length as uterine region. Uterine region 2.8

(n = 1) mm long, i.e. 11% of total body length, 2.1

(n = 1) mm wide. Postovarian region very long, 17.6

(n = 1) mm in length, i.e. 75% of total body length,

tapering posteriorly, with very long caudal portion,

14.1 (n = 1) mm in length, i.e. 60% of total body

length and 80% of postovarian region.

Longitudinal musculature in 2 distinct layers

throughout body (Fig. 5E,F,H); both layers separated

by parenchyma containing excretory canals. Excre-

tory canals usually extend posteriorly as 2 principal

lateral canals and some half dozen anastomosed

canals. Excretory bladder median, near posterior

extremity.

Scolex bulbous (Fig. 3D), with maximum width at

mid-level, with longitudinal furrows, without trans-

verse band of more darkly stained cells; apical

introversion present in single specimen, but not

observed in others; scolex base 0.7–1.0 (n = 2) mm

wide. Neck 0.2 (n = 2) mm long.

Testes medullary, subspherical, c.80 in diameter,

numerous, in several layers, envelope vas deferens

and cirrus-sac, reach back to level of 2–4 anterior-

most uterine coils; anteriormost testes located c.200

posterior to scolex. Cirrus-sac spherical, 170–

252 9 173–245 (n = 2), narrow compared with

width of body. Male genital pore 34 9 58 (n = 1).

Ovary follicular, bilobed, H-shaped to almost U-

shaped. Ovarian arms short, 0.7 (n = 2) mm long,

connected by wide ovarian isthmus; anterior arms

much longer than short posterior arms. Vagina

tubular, straight.

Vitelline follicles medullary, small, c.35 in diam-

eter, numerous, begin 250 posterior to scolex base,

forming single lateral row on each side of body, with

median follicles in postovarian region, reach poste-

riorly only to anterior fifth or quarter of postovarian

region.

Uterus tubular, strongly coiled. Uterine field

relatively short, 2.2 (n = 1) 9 1.3 (n = 1) mm;

posterior uterine coils enveloped laterally by ovarian

arms. Female genital pore 36 9 22 (n = 1). Gonop-

ores open separately; common genital atrium absent.

Eggs oval, 33 9 22, operculate.

Remarks

Woodland (1937) described Wenyonia longicauda

based on 13 specimens from two Synodontis gambi-

ensis at two localities in Sierra Leone and differenti-

ated the species from other Wenyonia spp. by the

following characteristics: (i) the possession of a long

caudal portion, with vitelline follicles not extending

beyond the anterior quarter of the postovarian region

(see Fig. 2F); (ii) an ovary with relatively short ovarian

arms; (iii) a bulbous scolex (see Fig. 3D); (iv) a body

surface with a rectangular pattern of longitudinal and

transverse grooves; and (v) a straight vagina.

Troncy (1978) reported W. longicauda from

S. frontosa in Chad, but these tapeworms were

deformed and strongly contracted (see fig. 1 in

Troncy, 1978) and differed from W. longicauda in a

number of morphological characteristics, such as the

small size of the body, the shape of the ovary (the

posterior arms were longer than the anterior ones) and

a relatively short caudal portion. Therefore, it is

assumed that Troncy (1978) misidentified another

species of Wenyonia.

W. longicauda appears to be a rare parasite, with

no reliable record published since its original

description in 1937. It is possible that the distribution

of the species is limited to West Africa. New material

of W. longicauda is needed to better describe its

morphology and to confirm its validity.

Wenyonia minuta Woodland, 1923

Syn. Wenyonia mcconnelli Ukoli, 1972 (new

synonym)

Type-host: Chrysichthys auratus (Geoffroy Saint-

Hilaire) (Siluriformes: Claroteidae) (probably an

accidental host).

Additional hosts: Synodontis caudovittata Boulenger,

S. frontosa Vaillant, S. nigrita Valenciennes, S. schall

Schneider, S. serrata Ruppell (all new hosts).

Type-locality: River Nile at Khartoum, Sudan.

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Geographical distribution: Africa: basins of the

Rivers Nile (Sudan) and Omo (Kenya – Turkana

Lake).

Site of infection: Small intestine.

Prevalence and intensity of infection: Kenya: Loiy-

angalani: prevalence 6% and intensity (1) (n = 17;

S. schall); Todonyang: prevalence 8% and intensity 1

(n = 12; S. frontosa); prevalence 14% and intensity 6

(range: 1–4; mean: 2; n = 22; S. schall); Sudan:

Girba: prevalence 15% and intensity 5 (range: 1–2;

mean: 1; n = 27; S. frontosa); prevalence 20% and

intensity 1 (n = 5; S. nigrita); prevalence 6% and

intensity 1 (n = 17; S. schall); Kostı: prevalence 25%

and intensity 1 (n = 4; S. caudovittata); prevalence

66% and intensity 4 (range: 1–3; mean: 2; n = 3;

S. serrata); Sennar: prevalence 29% and intensity 8

(range: 1–3; mean: 2; n = 14; S. schall).

Type-specimens: Holotype in BMNH.

References: Woodland (1923, 1926), Ukoli (1972).

Material studied: Holotype from Chrysichthys aura-

tus, River Nile, Khartoum, Sudan, 1913 (BMNH No.

1961.3.14.47); one specimen from Synodontis schall,

Lake Turkana, El-Molo Bay, Kenya, 2007, collected

by M. Jirku; six specimens from S. frontosa and S.

schall, Lake Turkana, Todonyang, Kenya, 2008,

collected by M. Jirku & M. Oros; eight specimens

from S. frontosa, S. nigrita and S. schall, Atbarah

River, Girba, Sudan, 2008, collected by T. Scholz &

A. de Chambrier; five specimens from S. serrata and

S. caudovittata, White Nile River, Kostı, Sudan,

2008, collected by T. Scholz & A. de Chambrier;

eight specimens from S. schall, Blue Nile River,

Sennar, Sudan, 2008, collected by T. Scholz & A. de

Chambrier (BMNH 2010.8.10.12–13; IPCAS C-571;

MHNG 72936; USNPC 103416, 103417).

Redescription (Figs. 2,E, 3E,F, 4J–L, 5C,D,

8A,B, 9B,D)

[Based on 10 complete hot formalin-fixed specimens

from Synodontis caudovittata, S. frontosa, S. nigrita,

S. schall and S. serrata in Kenya and the Sudan.]

Body 6.8–12.4 (n = 8; 4.2) mm long, flattened, either

stout and wide or elongate and slender, with maxi-

mum width of 0.8–3.2 (n = 10; 0.8) mm at uterine

region; very short postovarian region with wide

longitudinal excretory canals (Figs. 8A, 9D).

Scolex 1.6–2.1 (n = 8; 1.0) mm long, representing

16–29% (n = 8; 23%) of total body length.

Testicular region 0.6–2.2 (n = 8; 0.8) 9 0.8–2.5

(n = 9; 1.2) mm, i.e. 9–27% (n = 8; 20%) of total

body length, almost as long as scolex, narrowing

slightly towards cirrus-sac. Uterine region 3.3–7.2

(n = 10; 2.0) 9 0.8–3.3 (n = 10; 1.3) mm, i.e.

38–58% (n = 8; 47%) of body length, about twice

as long as scolex and testicular region, with maxi-

mum width at mid-level. Postovarian region very

short, 0.9–1.5 (n = 10; 0.4) mm long, i.e. 9–16%

(n = 8; 10%) of body length, tapered or subconical,

with rounded, stumpy tip at posterior extremity

(Fig. 8A,B).

Inner longitudinal musculature formed by single

narrow layer of isolated bundles of muscle fibres

(Fig. 5C,D). Excretory canals prominent, numerous,

indistinct at base of scolex, scattered throughout

cortical parenchyma; 17–22 canals almost completely

occupy cortical layer in testicular and uterine regions,

increase in size and decrease in number posteriorly,

very wide (up to 180 in diameter) in postovarian

region (Figs. 8A, 9D). Excretory bladder elongate to

pyriform, thick-walled; excretory pore terminal.

Scolex 0.6–1.9 (n = 8; 0.7) mm wide at its base

(deformed, collapsed in holotype – Fig. 8B), with

21–39 shallow longitudinal furrows (Fig. 4J–L),

small apical ring with blister-like extrusion at anterior

extremity and wide transverse band of darkly stained

cells near posterior end, either relatively long,

narrow, tapering towards anterior end and as wide

as testicular region (Figs. 3E, 4J,K), or almost hastate

(sensu Mackiewicz, 1994, fig. 5.10), with base wider

than testicular region and rounded anteriorly

(Figs. 3F, 4L).

Testes medullary, subspherical, 60–120 (n = 90;

47–65) 9 48–87 (n = 90; 32–40), 189–302 (n = 7;

172) in number, occupy about half width of

testicular region of body, envelop cirrus-sac, extend

from base of scolex posterior to level of 1–3

anteriormost uterine coils. Cirrus-sac oval, 480–620

(n = 8; 234) 9 240–370 (n = 8; 214), overlapped

by uterine coils in some specimens. Male genital

pore 47–78 9 86–135 (n = 8), opens into shallow

common genital atrium (Fig. 9B), 72–105 9 61–83

(n = 8).

Ovary follicular, bilobed, H-shaped, relatively

small; arms 0.6–1.4 (n = 20; 0.4–0.5) mm long,

connected by median, relatively short but wide

isthmus (Fig. 9D); ovarian follicles similar in size

to vitelline follicles (Fig. 9D); posterior arms curved

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inwards. Vagina tubular, sinuous, 27–38 (n = 10;

33–38) wide. Seminal receptacle 67–133 9 50–95

(n = 10), anterodorsal to ovarian isthmus (Fig. 9D).

Vitelline follicles medullary, extensive, 24–118

(n = 269; 43) 9 18–80 (n = 270; 18), slightly

increasing in size posteriorly, begin short distance

posterior to anteriormost testes (Fig. 3E,F) and

0.06–0.17 (n = 7; 0.17) mm posterior to scolex base,

in 2 lateral rows, with medially dispersed follicles

in testicular region (Figs. 3F, 8A,B); follicles end

110–280 (n = 9; 190) from posterior extremity.

Uterus tubular, forms tightly coiled loops; uterine

field 2.8–6.8 (n = 9; 1.7) mm long, with maximum

width of 0.5–2.2 (n = 9; 0.6) mm at about mid-level,

enveloping posterior part of cirrus-sac and genital

pores. Uterine glands absent. Female genital pore

36–61 (n = 8; 55) 9 73–107 (n = 8; 90), opens into

shallow common genital atrium (Fig. 9B).

Eggs oval, operculate, with smooth surface, 32–46

(n = 90; 33–40) 9 16–26 (n = 90; 20–26).

Fig. 8 A, B, Wenyonia minuta Woodland, 1923: A, from

Synodontis schall, Lake Turkana, Kenya; and B, from

Chrysichthys auratus, River Nile, Sudan (holotype; BMNH

No. 1961.3.14.47); C, W. synodontis Ukoli, 1972 from S.schall, Lake Turkana. Entire worm, dorsal (A,C) and ventral

(B) views. Scale-bars: 1 mm

b

Fig. 9 A, Wenyonia acuminata from Synodontis acanthomias, River Congo, Democratic Republic of the Congo; B, D, W. minutaWoodland, 1923 from S. frontosa, Lake Turkana, Kenya (B) and S. serrata, River Nile, Sudan (D); C, E, W. youdeoweii Ukoli, 1972

from S. schall, River Nile. Cirrus-sac, ventral view (A, B, C); ovarian region, ventral view (D, E). Abbreviations: cs, cirrus-sac; ed,

ejaculatory duct; ex, excretory canal; fp, female genital pore; ga, genital atrium; ist, ovarian isthmus; mg, Mehlis’ gland; mp, male

genital pore; of, ovarian follicle; sr, seminal receptacle; ut, uterus; vag, vagina; vd, vas deferens; vf, vitelline follicle. Scale-bars:

A,D, 300 lm; B, 100 lm; C,E, 500 lm

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Remarks

Tapeworms identified as Wenyonia minuta have a

short, leaf-like body, with the maximum width in the

uterine region, a very short postovarian region and

prominent, very wide excretory canals occupying

almost the entire cortical parenchyma in the testicular

and uterine regions, an ovary with relatively short,

wide arms and vitelline follicles situated medially

between the testes.

This poorly known species, which has never been

found since its original description, was described by

Woodland (1923) based on a single, apparently

deformed specimen found in the claroteid catfish

Chrysichthys auratus at Khartoum, Sudan. Examina-

tion of the holotype has shown that two taxonomi-

cally important characteristics were described

incorrectly by Woodland (1923): (i) the anterior

ovarian arms are as long as the posterior ones and do

not extend to the level of the gonopores (vitelline

follicles were apparently mistaken for ovarian folli-

cles); and (ii) the vitelline follicles are also present

medially within the testicular field (Fig. 8B).

The holotype of W. minuta differs from recently

collected specimens in its smaller size, absence of

longitudinal furrows on the scolex and the alleged

absence of a common genital atrium. However, these

differences are negligible and they most probably

reflect the fact that Woodland’s specimen was

strongly contracted and deformed (Fig. 8B). There-

fore, all of the specimens are considered to be

conspecific.

Wenyonia minuta is also indistinguishable from W.

mcconnelli Ukoli, 1972 in almost all morphological

characteristics, such as body shape, including a very

short postovarian region, and the proportions of the

body parts. The latter species was inadequately

described based on five whole-mounts and two

cross-sectioned specimens out of 15 specimens found

in 10 Synodontis clarias from the River Niger at

Shagunu, Nigeria (Ukoli, 1972). However, several

characteristics reported by Ukoli (1972) are ques-

tionable or apparently erroneous, such as the asym-

metrical distribution of the anteriormost vitelline

follicles and testes, the anterior extent of the ovarian

arms, which were confused with vitelline follicles

(the same mistake was made by Woodland, 1923 in

the description of W. minuta), the arrangement of the

postovarian vitelline follicles in two lateral rows, and

the extraordinarily large eggs (Ukoli, 1972 probably

miscalculated the size of the eggs of all of his

species).

The only obvious difference between W. mccon-

nelli and W. minuta exists in the shape of the scolex,

which is rugomonobothriate in the former species,

thus resembling that of W. virilis. However, the worm

(probably the holotype of W. mcconnelli) illustrated

by Ukoli (1972) does not seem to have a natural

shape, which is obvious from the corrugated lateral

margins of the scolex and its base with centred

longitudinal furrows. The scolex reaches almost its

maximum width at its base, but then ends abruptly.

This clearly resembles a strong local contraction of

the scolex, which might be an indication of a change

in its natural shape. Therefore, W. mcconnelli is

synonymised with W. minuta until new, well-fixed

material from Nigeria demonstrates that it is actually

a distinct species, well separated morphologically and

genetically from W. minuta.

Some variability in the shape of the body (i.e. from

elongate-narrow to stout-wide) and scolex (from

elongate, tapering anteriorly and of the same width

as the testicular region, see Figs. 3E, 4J,K, to almost

hastate and wider than the testicular region, see

Figs. 3F, 4L) was observed among specimens of W.

minuta. However, all specimens were otherwise

identical, and their conspecificity was confirmed by

molecular data (Table 1) and discriminant analysis of

the morphological data (data not shown).

Chrysichthys auratus probably represents an acci-

dental host of W. minuta, because this tapeworm has

Table 1 Pairwise nucleotide differences of partial (D1–D3)

28S rDNA sequences (length 1,130 nt) of Wenyonia spp.

Values above the diagonal: percentage of nucleotide differ-

ences (uncorrected ‘‘p’’, gaps treated as missing data). Values

below the diagonal: total number of nucleotide differences

Wenyonia spp. No. 1 2 3 4 5 6

W. acuminatagenotype 1

1 - 1.2 30.1 29.5 29.8 28.9

W. acuminatagenotype 2

2 2 - 30.3 29.7 30.0 29.1

W. youdeoweiigenotype 1

3 49 49 - 0.6 18.0 4.3

W. youdeoweiigenotype 2

4 48 48 1 - 18.0 3.7

W. minuta 5 48 48 29 29 - 16.7

W. virilis 6 47 47 7 6 27 -

100 Syst Parasitol (2011) 79:83–107

123

never been found in this claroteid catfish subsequent to

its original description. The present authors examined

44 C. auratus from the River Nile in the Sudan, but did

not find any caryophyllidean cestode. In contrast, the

present study has shown that W. minuta is a widely

distributed parasite of Synodontis spp. and was found

in five species in Kenya and the Sudan.

Wenyonia synodontis Ukoli, 1972

Type-host: Not designated, but Synodontis sorex

Gunther was listed first and thus is considered to be

the type-host.

Additional hosts: S. gambiensis Gunther, S. schall

Schneider (new host), S. vermiculata Daget.

Type-locality: River Niger at Shagunu, Nigeria.

Geographical distribution: Africa: basins of the

Rivers Niger (Nigeria) and Omo (Kenya – Lake

Turkana).

Site of infection: Small intestine.

Type-specimens: Not available, almost certainly do

not exist.

Reference: Ukoli (1972).

Material studied: One specimen from S. schall, Lake

Turkana, El-Molo Bay, Kenya, 2007, collected by M.

Jirku (IPCAS C-572).

Redescription (Figs. 2G, 8C)

[Based on single complete, hot formalin-fixed spec-

imen from Synodontis schall.] Body 12.9 (n = 1;

11.2–20.0) mm long by 2.0 (n = 1; 1.3–3.5) mm

wide, robust, with widely rounded posterior extremity

(Figs. 2G, 8C).

Scolex 1.9 (n = 1; 1.1–1.7) 9 2.0 (n = 1; 1.2–

2.4) mm, representing 14% (n = 1; 9%) of total body

length. Testicular region 2.2 (n = 1; 1.9–2.3) 9 1.3

(n = 1; 0.9–2.7) mm, i.e. 17% (n = 1; 12%) of body

length, narrower than scolex base. Uterine region 3.9

(n = 1; 2.2–6.5) 9 1.6 (n = 1; 1.3–3.5) mm, i.e.

30% (n = 1; 33%) of body length, with slight

constriction at mid-level. Postovarian region 4.9

(n = 1; 6.0–9.0) mm long, which represents 38%

(n = 1; 46%) of body length (Fig. 2G).

Lateral excretory canals wide, with median canals

narrow, enlarging posteriorly. Excretory bladder

elongate, small, thin-walled, near posterior extremity;

excretory pore terminal.

Scolex rugosagittate, i.e. sagittate in shape with 23

(n = 1; 10 – probably erroneous) longitudinal fur-

rows, 11 and 12 on each body surface; scolex almost

as long as wide, without apical inversion and

transverse band of darkly stained cells (Fig. 8C).

Testes medullary, subspherical, 93–100 (n = 10;

160–190) 9 55–63 (n = 10; 80–130), 184 (n = 1;

c.240) in number; anteriormost testes begin at short

distance posterior to scolex (Fig. 8C); posteriorly

testes reach to first uterine coils, surrounding vas

deferens and cirrus-sac. Cirrus-sac oval to almost

spherical, 420 (n = 1; 500) 9 240 (n = 1; 330);

posterior part, including ejaculatory duct and cirrus,

overlapped by anteriormost uterine coils. Male gen-

ital pore 50 9 89 (n = 1). Common genital atrium

absent.

Ovary follicular, bilobed, H-shaped; ovarian arms

0.8–0.9 (n = 2; 1.7) mm long, wide, not extending

far anterior, connected by short, wide isthmus;

anterior arms slightly longer than posterior ones;

posterior arms curved medially (Fig. 8C). Vagina

tubular, slightly sinuous. Seminal receptacle rela-

tively small, 106 9 82 (n = 1), dorsal to ovarian

isthmus.

Vitelline follicles 36–56 (n = 30; 90–100) 9

20–39 (n = 30; 50); follicles start 0.4 (n = 1) mm

posterior to scolex base, form pair of lateral bands,

extend to postovarian region, increasing in size

posteriorly; postovarian follicles extensive, reaching

0.5 (n = 1) mm from posterior extremity (Fig. 8C).

Uterus tubular, with many convoluted loops.

Uterine field wide (c.2/3 of maximum body width),

3.5 (n = 1) 9 1.3 (n = 1) mm. Female genital pore

46 9 82 (n = 1), opens short distance posterior to

separate male pore.

Eggs elongate, operculate, with rough surface,

43–48 (n = 10; 40–56) 9 16–22 (n = 10; 13–14),

embryonated.

Remarks

The specimen from Lake Turkana is considered to be

conspecific with W. synodontis because it possesses

the following characteristics typical of this species

(Ukoli, 1972): (i) a widely rounded postovarian

region; (ii) postovarian vitelline follicles reaching

almost to the posterior extremity; (iii) a rugosagittate

scolex devoid of a transverse band of dark cells and

Syst Parasitol (2011) 79:83–107 101

123

an apical inversion; and (iv) the scolex is almost as

long as the testicular region (i.e. 14% and 17%,

respectively). Ukoli’s (1972) specimens had more

and larger testes than the worm from Kenya, but this

difference is negligible and apparently reflects intra-

specific variability in otherwise identical specimens.

Wenyonia synodontis was originally described from

three host species in Nigeria (Ukoli, 1972), but

unfortunately no type-specimens have been deposited

in a helminthological collection. The single specimen

from Kenya represents a new host and geographical

record. All hosts of W. synodontis occur in the Niger

River basin, whereas S. schall has a much wider

distribution throughout Africa (Froese & Pauly, 2010).

In fact, W. synodontis closely resembles in many

morphological characteristics W. virilis and may well

represent contracted specimens of the latter species.

However, the only specimen found in the present

study was fixed with formalin and thus no molecular

data are available to confirm the validity of this

taxon. Therefore, W. synodontis is tentatively

retained as a valid species.

Wenyonia youdeoweii Ukoli, 1972

Type-host: Synodontis gobroni Daget.

Additional hosts: S. caudovittata Boulenger, S. schall

Schneider, S. serrata Ruppell (all new host records).

Type-locality: River Niger at Shagunu, Nigeria.

Geographical distribution: Africa: basins of the

Rivers Niger (Nigeria) and Nile (Sudan).

Site of infection: Small intestine.

Prevalence and intensity of infection: Shagunu,

Nigeria: prevalence 100% (n = 1) and intensity 58

(S. gobroni); Kostı, Sudan: prevalence 25% and

intensity 6 (n = 4; S. caudovittata); prevalence 12%

and intensity 31 (range: 1–16; mean: 10; n = 26;

S. schall); prevalence 100% and intensity 5 (range:

1–2; mean: 2; n = 3; S. serrata).

Type-specimens: Not available, almost certainly do

not exist.

Reference: Ukoli (1972).

Material examined: One specimen from Synodontis

caudovittata, six specimens from S. schall and three

specimens from S. serrata, White Nile River, Kostı,

Sudan, 2008, collected by T. Scholz & A. de

Chambrier (BMNH 2010.8.10.19; IPCAS C-573;

MNHG 72935; USNPC 103422).

Redescription (Figs. 2H, 3G,H, 4M,N, 5G, 7B,

9C,E)

[Based on 6 complete and 2 incomplete, hot formalin-

fixed specimens from Synodontis caudovittata, S.

schall and S. serrata.] Body elongate, 37.2–46.3

(n = 4; 16.8–59.1) mm long, with maximum width of

1.5–2.5 (n = 6; 1.0–3.5) mm at uterine region,

narrowing at level of gonopores, with distinct,

15.7–24.4 (n = 4) mm long caudal portion tapering

posteriorly (Figs. 2H; 7B).

Scolex 0.8–1.3 (n = 6; 0.7–2.9) 9 0.9–1.1

(n = 6; 0.9–2.5) mm, representing 2–3% (n = 4;

4%) of total body length. Testicular region 4.5–7.0

(n = 6; 1.3–5.9) 9 1.1–1.5 (n = 6; 0.8–3.1) mm at

mid-level, relatively short, representing 10–16%

(n = 4; 9%) of total body length, slightly shorter

than uterine region, with distinct constriction at level

of cirrus-sac (Fig. 7B). Uterine region 3.9–8.2 (n =

5; 3.6–10.0) 9 1.5–2.5 (n = 6; 1.1–3.5) mm, i.e.

8–19% (n = 4; 16%) of body length. Postovarian

region 23.2–37.1 (n = 4; 11.2–40.1) mm long, i.e.

62–80% (n = 4; 71%) of body length. Caudal portion

15.7–24.4 (n = 4) mm long, gently tapered posteri-

orly (Figs. 2H, 7B).

Inner longitudinal musculature forms 2 narrow

bands of individual muscle fibres (Fig. 5G). Main

longitudinal excretory canals narrow, external to

testes and vitelline follicles, mostly in cortical

parenchyma; scolex with anastomosed canals; lateral

canals increase in size towards uterine region. Eight

canals observed in postovarian region, decreasing in

number posteriorly, with just 2–4 wide canals present

near posterior extremity. Excretory bladder thick-

walled, elongate, terminal.

Scolex short, weakly deltorugomonobothriate, i.e.

triangular, with apical introversion and 13–19 (10–

12) longitudinal furrows (Figs. 3G,H, 4M,N); scolex

0.8–1.3 (n = 6; 0.7–2.9) 9 0.9–1.1 (n = 6; 0.9–2.5)

mm, with narrow transverse band of darkly stained

cells near posterior end (Fig. 3G,H); scolex base as

wide as testicular region (Fig. 3G) or slightly

narrower (Fig. 3H). Neck 0.3–0.5 (n = 6) mm long.

Testes medullary, oval, 122–162 (n = 50; 180–

200) 9 85–121 (n = 50; 120–200), 154–227 (n = 5;

250) in number; anteriormost testes located 0.3–

0.6 (n = 6) mm posterior to scolex, reaching poste-

riorly alongside cirrus-sac and 2–4 anteriormost

coils of uterus. Cirrus-sac oval, 280–530 (n = 6;

102 Syst Parasitol (2011) 79:83–107

123

570) 9 160–250 (n = 6; 400). Male genital pore 40–

47 9 72–109 (n = 6). Common genital atrium

absent (Fig. 9C).

Ovary follicular, bilobed, H-shaped; ovarian arms

long and narrow (Fig. 9E) to short and wide (Fig. 7B),

1.5–2.1 (n = 10; 3.0) mm long, connected by median

isthmus; anterior ovarian arms alongside 4–9 posteri-

ormost uterine coils (Figs. 7B, 9E). Vagina tubular,

slightly sinuous, 30–61 (n = 10) wide. Seminal

receptacle small, 121–175 9 95–119 (n = 5), broadly

oval, anterodorsal to ovarian isthmus.

Vitelline follicles 49–99 (n = 150; 50–80) 9

34–71 (n = 150; 40–80), of almost same size

throughout body except for posteriormost follicles,

well separated from testes, begin 0.5–0.9 (n = 6) mm

posterior to scolex base, form single lateral row on

each side of body interrupted at level of cirrus-sac;

postovarian follicles form single wide band of

deeply-lobed vitelline follicles (Fig. 7B).

Uterus tubular, strongly coiled. Uterine field

5.6–7.4 (n = 5) 9 0.9–1.4 (n = 6) mm; anterior

uterine coils overlap posterior part of cirrus-sac.

Female genital pore 31–46 9 54–81 (n = 6), opens

20–34 (n = 6; 50) posterior to separate male pore.

Eggs oval, operculate, with rough surface, 37–

43 (n = 50; 63–76) 9 18–24 (n = 50; 31–38),

embryonated.

Remarks

The specimens from the Sudan were identified as

Wenyonia youdeoweii based on the following diag-

nostic characteristics: (i) the scolex is weakly delto-

rugomonobothriate, with its base as wide as the

testicular region; (ii) the postovarian region repre-

sents two-thirds of the body length (62–80% in our

material, 71% in the original description); (iii) the

testicular region represents much less than a fifth of

the body length (10–16% and 9%, respectively); and

(iv) the vitelline follicles do not extend to the

posterior half of the postovarian region.

The arrangement of vitelline follicles in specimens

from the Sudan is slightly different to that of W.

youdeoweii from Nigeria, because the Sudanese

specimens possess only one pair of longitudinal rows

within the testicular and uterine regions (versus,

allegedly, two longitudinal rows on each side – Ukoli,

1972; but see his fig. 1). An additional specific

feature of W. youdeoweii observed in the present

material is the presence of a distinct constriction of

the body at the level of the gonopores (Fig. 7B),

which was illustrated, but not mentioned, in the

original description (Ukoli, 1972).

Since the type-specimens of W. youdeoweii were

not available, it was not possible to confirm the

extraordinarily large size of the eggs reported in

the original description. However, measurements of

the eggs of all of the species described by Ukoli

(1972) were about 1.5–2 times larger than those of all

Wenyonia specimens studied by Woodland (1923,

1937) and the present authors, which casts doubt

upon Ukoli’s data.

Comparative sequence analysis

A comparative analysis of the partial 28S rRNA gene

sequences demonstrated six different genotypes: We-

nyonia acuminata (n = 2) revealed two genotypes,

differing in one transversion (T–G) and one degener-

ated position; W. minuta (n = 8) revealed a single

genotype; W. youdeoweii (n = 2) represented two

genotypes differing in one transition (C–T); and all

samples of the morphologically variable W. virilis

(n = 22) were identical, exhibiting only a single

genotype. The overall sequence divergence (uncor-

rected ‘‘p’’) ranged from 0.6 to 30.3% (Table 1). The

distances between the two genotypes of W. acuminata

(p = 1.2%) and W. youdeoweii (p = 0.6%) were much

smaller than the remaining interspecific distances

(Table 1). Both isolates of the two species are thus

regarded as conspecific. The sequence distances

between the four species varied within a wide range

(3.7–30.3%, i.e. 6–49 nucleotides; Table 1).

Wenyonia, represented by six genotypes, appears as

a monophyletic clade in the BI phylogram (Fig. 10). As

revealed by the present analysis of the partial 28S

rRNA gene sequences, the Wenyonia clade is divided

into two well-supported lineages: (i) W. acuminata

with W. minuta; and (ii) W. virilis with W. youdeoweii,

the two latter species being rather similar to each other

in their general body morphology.

Key to the identification of Wenyonia spp.

This key is simplified as much as possible, with only

the most obvious characteristics maintained. However,

Syst Parasitol (2011) 79:83–107 103

123

we strongly recommend verification of each species

using the individual species diagnosis provided in the

redescriptions above. In addition, only well-fixed

material (uncontracted and unflattened specimens)

should be used.

1. Body nematodiform, of almost equal width

throughout the entire body (Figs. 2D, 7A);

vitelline follicles absent medially within the

postovarian region (arranged in two lateral

bands; Fig. 7A) ………….……. W. acuminata

– Body with other shape and maximum width in

the scolex or uterine region; vitelline follicles

present also medially within the postovarian

region ……………………………………….....2

2. Body lanceolate, with very short, conical

postovarian region (Figs. 2E, 8A,B); excretory

canals very wide, especially in the postovarian

region (Figs. 8A, 9D); vitelline follicles situ-

ated medially in the testicular region, mixed

with testes (Fig. 8A,B)……………...W. minuta

– Body with other shape; excretory canals less

prominent, narrower; vitelline follicles absent

medially within the testicular region…………...3

3. Anterior arms of the ovary much longer than

the posterior ones (Fig. 2F); caudal portion

(posterior part of the postovarian region without

vitelline follicles) very long, representing [ 4/5

of the postovarian region (Fig. 2F) ……………………………………………… W. longicauda

– Anterior ovarian arms of similar length to the

posterior arms; caudal portion \ 3/4 of the

postovarian region ……………………………………………………………………………...4

4. Postovarian region ends bluntly (Figs. 2G, 8C)

………………………………… W. synodontis

– Postovarian region tapers to a narrow caudal

extremity ………………………………….…..5

5. Scolex triangular, with its base as wide as, or

slightly narrower than, the testicular region;

scolex not distinctly separated (Figs. 2G, 3G,H,

4M,N) from testicular region; postovarian

region not curled (Fig. 7B) ……………………………………………………W. youdeoweii

– Scolex conical to sagittate, always wider than

the testicular region (Figs. 1, 2A–C, 3A,B, 4A–

E); distinctly separated (Figs. 3A,B, 4A–E)

from latter region; postovarian region curled

(Fig. 1) …………………………….....W. virilis

Discussion

On the basis of a study of extensive material of

Wenyonia spp. from several host species in four

African countries, a critical review of the literature

and the examination of the available type-specimens

of four taxa, the number of recognised species of the

genus is reduced from eight to six. This study has also

shown that morphological intraspecific variability

exists in some species, with the highest degree of

polymorphism present in the most widely distributed

species, W. virilis, which also infects the widest

spectrum of fish hosts.

Different morphotypes observed, however, seem

to represent only intraspecific variation, since no

genetic differences in the partial 28S rDNA were

found between specimens with a different morphol-

ogy. It is, therefore, necessary to take into account

this morphological variability in future taxonomic

studies on Wenyonia spp. Research using various

molecular approaches suitable for studies of intra-

and interspecific variability, phylogenetics and pop-

ulation genetics is currently being undertaken to

provide more information on the morphologically

Fig. 10 Bayesian Inference (BI) phylogram between Wenyo-nia spp. inferred from partial (D1–D3) 28S rDNA sequences,

employing the GTR ? C8 ? I substitution model. Nodal

support is shown as posterior probabilities. Monobothrioideschalmersius (Woodland, 1924) (Lytocestidae) from Clariascatfish in Africa served as the outgroup

104 Syst Parasitol (2011) 79:83–107

123

variable populations of Wenyonia, which may serve

as a suitable model for evolutionary, phylogeograph-

ical and populational investigations into these

endemic parasites of African freshwater catfishes.

The present study has also demonstrated that the

fixation method can considerably change the mor-

phology of the worms studied, as has also been

observed in other caryophyllideans (Oros et al.,

2010). Tapeworms described by W.N.F. Woodland

and F.M.A. Ukoli appear to have been contracted or

deformed and are thus unsuitable for comparative

analyses and taxonomic studies, because various

taxonomically significant features, e.g. body and

scolex shape, as well as the proportions of individual

body parts, may be significantly affected by contrac-

tion. For example, W. synodontis, tentatively retained

as valid, may just represent strongly contracted

specimens of W. virilis with a robust body, a short,

wide scolex and a bluntly-ended, rounded posterior

extremity. We strongly recommend the use of the hot

formalin fixation method described above for all

cestodes whenever morphological analyses are

required. This method invariably produces unde-

formed and non-contracted specimens, with both

external and internal features being well preserved

and readily visible. It, furthermore, made it possible

to obtain comparable samples of tapeworms collected

by different persons and from different hosts and

regions (Oros et al., 2010).

Species of Wenyonia are characterised by pre-

equatorial genital pores, the absence of uterine

glands, embryonation of the eggs in utero and a very

long, tail-like postovarian region in most species, i.e.

a combination of features distinguishing this genus

from all other caryophyllidean genera (Mackiewicz,

1994). Members of the genus are distributed through-

out the main river basins of sub-Saharan Africa with

a remarkable extension of their range into the

Palaearctic region along the River Nile as far north

as the Nile delta on the Mediterranean coast (northern

Egypt).

The host-specificity of Wenyonia spp. is not as

narrow (oioxenous, sensu Euzet & Combes, 1980) as

claimed by Ukoli (1972). According to this author,

each species of Synodontis harbours a unique species

of Wenyonia, without concurrent infections, thus

avoiding interspecific competition. In fact, three of

the six valid Wenyonia spp., namely W. minuta,

W. virilis and W. youdeoweii, were found to infect

more than one host species (as many as 13 Synodontis

spp. in the case of W. virilis) and thus can be

considered as stenoxenous (sensu Euzet & Combes,

1980). In addition, S. gambiensis was infected with

two species, namely W. longicauda and W. synodon-

tis, as reported by both Woodland (1923) and Ukoli

(1972). Importantly, we have recorded the co-occur-

rence of W. minuta with W. virilis and/or W.

youdeoweii in as many as 10 of 15 Synodontis spp.

examined. Wenyonia spp. have also been reported

from claroteid and clariid catfishes, but these records

are doubtful and most probably represent accidental

infections or host or parasite misidentifications.

Acknowledgements The authors are much obliged to the two

referees for their valuable comments and critical remarks. They

also express their gratitude to R. Kuchta (Institute of

Parasitology, Ceske Budejovice – IP) and M. Oros

(Parasitological Institute, Slovak Academy of Sciences,

Kosice, Slovakia) for their significant contribution to the

present work. Sincere thanks are due to A. de Chambrier

(Natural History Museum, Geneva, Switzerland) for his help in

field sampling in the Sudan, to B. Wicht (Instituto Cantonale di

Microbiologia, Bellinzona, Switzerland), J. Brabec (IP) and M.I.

Blasco-Costa (Universitat de Valencia, Valencia, Spain) for help

with DNA sequencing and phylogenetic analyses, and M.

Borovkova, B. Skorıkova and M. Tesarova (IP) for excellent

technical assistance. B. Koubkova (Masaryk University, Brno,

Czech Republic) provided Wenyonia specimens from Senegal

and E.A. Harris (Natural History Museum, London, UK) data on

the museum material of Wenyonia. The stay of A. de Chambrier

and T.S. in the Sudan during 2006 and 2008 could not have been

possible without the support of numerous Sudanese colleagues,

in particular M.M. Abdelrahman, S.Y.O. Elsheikh, H.A. Hassan,

Z.A.A. Omer (all from the Faculty of Science, University of

Khartoum, Khartoum, Sudan) and K.M. Hamad (University of

Khartoum), who helped considerably during the fieldwork.

Thanks are also due to A. Osman and M.A. Abdalla (White Nile

Fisheries Research Station, Kostı and the National Institute of

Natural Sciences, Khartoum, Sudan) for support. B.C.S. is

indebted to A. Kostadinova for her suggestions and support.

Thanks are due to A. Scott-Emuakpor and P. Ekeh for their help

in searching for the deposition of Ukoli’s type and voucher

specimens. M.J. is grateful to M.L.J. Stiassny (Department of

Ichthyology, American Museum of Natural History, New York,

Grant DEB-0542540 from the National Science Foundation), R.

Monsembula (Faculty of Science, University of Kinshasa,

Kinshasa, Democratic Republic of the Congo) and V.

Mamonekene (Institute of Rural Development, University of

Marien Ngouabi, Brazzaville, Republic of the Congo) for their

considerable support during field work in the Democratic

Republic of the Congo in 2008. Several research stays in Kenya

between 2007 and 2009 could not have been realised without the

help and support of D. Modry, D. Jirsova and Milan Jirku (all

IP), M. Gelnar, R. Blazek, I. Prikrylova and S. Masova (all from

the Faculty of Science, Masaryk University, Brno), H. Charo-

Karisa, D. Lotuliakou and J. Malala (all from the Kenya Marine

Syst Parasitol (2011) 79:83–107 105

123

and Fishery Research Institute, Kisumu Centre and Kalokol

Field Station), Father S.J. Ochieng (Todonyang Catholic

Mission) and countless field assistants. T.S. and M.J.

acknowledge the Grant Agency of the Czech Republic

(Project No. 524/08/0885), Grant Agency of the Academy of

Sciences of the Czech Republic (Project No. KJB600960813)

and the Institute of Parasitology (Project Nos Z60220518 and

LC 522) for financial support. T.S. is also grateful for the

financial support to the National Science Foundation, USA (PBI

award Nos 0818696 and 0818823) and the SYNTHESYS

Programme of the European Union (GB-TAF-4782), which

supported his stay in London during 2008.

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