Clinostomoides Dollfus, 1950

Rensburg, Candice Jansen van, van As, Jo G. & King, Pieter H., 2013, New records of digenean parasites of Clarias gariepinus (Pisces: Clariidae) from the Okavango Delta, Botswana, with description of Thaparotrema botswanensis sp. n. (Plathelminthes: Trematoda), African Invertebrates 54 (2), pp. 431-431 : 432-434

Genus Clinostomoides Dollfus, 1950 Clinostomoides brieni Dollfus, 1950

Figs 1A , 2A–E ; Table 1

Clinostomoides brieni: Dollfus 1950: 77 , fig. 54; Manter & Pritchard 1969: 54–56, figs 1–4; Fischthal & Thomas 1970: 74–76, fig. 1.

Clinostomoides ophicephali (Tubangui & Masilungan, 1944) :Agarwal 1959: 17; Manter & Pritchard 1969: 56.

Clinostomoides dollfusi Agarwal, 1959: 13–16 , fig. 1; Manter & Pritchard 1969: 56.

Redescription:

Metacercaria.

Excysted metacercariae from gill chamber or branchial region move around freely ( Fig. 2A ). Body elongate, narrow, parallel lateral margins, extremities round with maximum width at acetabulum level or just pre-acetabular ( Figs 1A , 2B ). Cuticular spines fingerlike projections, pointed, occurring from level of posterior part of oral sucker or prepharynx to posterior extremity,unspined anteriorly ( Fig.2C ). Oral sucker small.Acetabulum larger than oral sucker. Prepharynx short; pharynx muscular, 0.18 in diameter; no apparent oesophagus. Caecal bifurcation pre-acetabular closer to oral sucker than to acetabulum, forming caecal shoulders before beginning descent from acetabular level; posteriorly caeca thick-walled, with short diverticula on median and lateral sides terminating just above excretory bladder ( Fig. 1A ). Testes transversely elongated, in posterior 1 / 6 – 1 / 7 body length; anterior testis crescent shaped extending across intercaecal space; posterior testis crescent to Y-shaped sometimes less wide, mostly dextral ( Fig. 2D ). Cirrus sac thick-walled, commashaped, inter-testicular, dextral ( Fig. 1A ). Genital pore just submedian to right, immediately anterior to posterior testis. Ovary small, intercaecal, longitudinally elongate. Uterus extending anteriorly on left side; uterine sac median, without lateral sacculations in posterior half of body, well separated from acetabulum, receiving uterus near middle; vitellarium undeveloped; no eggs ( Fig. 2D ). Excretory pore dorso-terminal ( Fig. 2E ); vesicle small, Y to V-shaped, entirely postcaecal, thick-walled, arms extending anteriorly on each side of body in extra-caecal position, uniting at anterior margin of oral sucker ( Fig. 1A ).

Material examined: BOTSWANA: 24 metacercariae, Okavango Delta, 5 Shakawe mainstream (18°26'05.0''S 21°54'23.0''E) ; 9 Kalatog channel (18°25'08.2''S 21°54'05.0''E) ; 5 Nxamaseri backwaters (18°37'34.9''S 22°06'24.4''E) ; 3 Mokoro lagoon (18°29'10.1''S 21°55'10.1''E) ; 2 Samochima lagoon (18°25'44.0''S 21°54'01.0''E) .

Site of infection: Gill chamber/branchial region.

Prevalence of infection: 26.1%.

Remarks: Clinostomoides brieni was described by Dollfus (1950) from the Goliath heron, Ardea goliath Cretzschmar, 1827 from the Congo. Agarwal (1959) described C. dollfusi occurring in siluroid fishes from India; however, this species was later synonymised with C. brieni by Manter and Pritchard (1969). They briefly redescribed the metacercaria from Clarias sp. from Rwanda and synonymised C. ophiocephali with C. dollfusi . They also suggested that C. brieni is the only species in the genus with its synonyms being C. dollfusi and C. ophicephali .

The material from the current survey is similar to C. brieni in having the testes, ovary and uteroduct in the same position, the uterine sac being removed far from the acetabulum and the latter being larger than the oral sucker. Specimens from this study differ from C. brieni described by Fischthal and Thomas (1970) in that the metacercariae are larger, oral and ventral suckers are slightly larger and the testes differ in shape. Considering the above mentioned morphological differences and similarities, specimens of the present material are assigned to C. brieni . This is the first record of C. brieni in the Okavango Delta, and the first documented record from Botswana.

Family Diplostomidae Poirier, 1886

Figures

Fig.1. Light microscope projection drawings of digeneans from Clarias gariepinus in the Okavango Delta: (A) Clinostomoides brieni Dollfus, 1950; (B) Neodiplostomum Railliet, 1919 type 1 metacercaria; (C) Phyllodistomum bavuri Boomker, 1984; (D) Phyllodistomum vanderwaali Prudhoe & Hussey, 1977; (E) Glossidium pedatum Looss, 1899; (F) Thaparotrema botswanensis sp. n. Scale bars: A, C – 1 mm; D – 0.3 mm; B, E – 0.1 mm; F – 0.2 mm.

Fig. 2. Light and scanning electron micrographs of Clinostomoides brieni Dollfus, 1950 (A–E) and Neodiplostomumtype 1 metacercaria (F–H) from Clarias gariepinusin the Okavango Delta:(A)excysted metacercariae; (B) whole mount;(C) spines on body surface; (D) reproductive system; (E) excretory pore; (F) metacercariae encysted in muscle; (G) oral sucker and pharynx; (H) holdfast organ. Scale bars:A, B – 1 mm; C – 2 µm, D, F – 0.1 mm; E – 20 µm; G – 0.05 mm; H – 0.01 mm.