Glossidium pedatum Looss, 1899

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 : 440-441

Glossidium pedatum Looss, 1899

Figs 1E , 3J–L ; Table 1

Glossidium pedatum: Looss 1899: 705–706 , fig. 27; Fischthal 1973: 166–167.

Afromacroderoides lazerae Khalil, 1972: 341–344 , fig. 1; Mashego & Saayman 1989: 19.

Redescription:

Elongate trematodes with truncated posterior end ( Figs 1E , 3J ). Body with maximum width at acetabulum level. Cuticle covered with tiny spines which are dense on anterior end of body, gradually diminishing posteriorly. Both suckers well developed, almost equal in size. Oral sucker slightly oval to spherical in shape ( Fig. 1E ). Acetabulum spherical. Prepharynx short. Pharynx fairly large, opens into oesophagus which may sometimes be indistinct. Intestinal caeca extend posteriorly, ending near posterior extremity of body. Testes tandem, oval-shaped, smooth ( Figs. 1E , 3K ). Testes separated from each other by number of eggs. Cirrus sac large, elongate, curves to right of acetabulum, contains bipartite seminal vesicle with posterior half being larger than anterior part ( Fig. 3L ). Common genital pore median or submedian, immediately anterior to acetabulum. Ovary round to oval situated posterior to, or next to cirrus sac. Uterus forming upward and downward loops reaching to posterior end of body, where it fills in almost whole post testicular space ( Fig. 1E ). Numerous yellow to brown operculate eggs present. Vitellarium irregularly shaped, extends laterally on either side of body from ovarian level to posterior margin of posterior testis.

Material examined: BOTSWANA: 21 adult specimens, Okavango Delta, Shakawe mainstream (18°26'05.0''S 21°54'23.0''E) .

Site of infection: Posterior third of intestine.

Prevalence of infection: 11.9%.

Remarks: Glossidium pedatum was first reported by Looss (1899) from Bagrus bajad (Forskål, 1775) and Bagrus docmak (Forskål, 1775) from the lower reaches of the Nile River. Fischthal (1973) collected and redescribed specimens of Glossidium pedatum from the intestine of C. gariepinus in Ethiopia, and noted that there were similarities between his material and Afromacroderoides lazerae Khalil, 1972 (also from C. gariepinus ). It was found that Khalil’s (1972) description corresponded to those of G. pedatum , and Mashego and Saayman (1989) thus synonymised A. lazerae with G. pedatum . Although Tkach (2008) treated Afromacroderoides as a synonym of Glossidium ; however, he did not consider G. pedatum and G. lazerae to be synonyms and thus made the new combination Glossidium lazerae on the basis of the length of the oesophagus.

The specimens from the present study are similar to G. pedatum described by Fischthal (1973) in that it possesses a four-lobed pharynx, the ovary and testes are in the same position; the vitellaria extend from the ovarian level to the posterior margin of the posterior testis; the prepharynx has a sphincter-like structure situated just anterior to the pharynx. On the basis of the above mentioned characteristics, specimens of the present material are thus assigned to G. pedatum . This is the first record of G. pedatum in the Okavango Delta, and the first documented record from Botswana.

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. 3. Light and scanning electron micrographs of Phyllodistomum bavuri Boomker, 1984 (A–C), Phyllodistomum vanderwaali Prudhoe & Hussey, 1977 (D–I) and Glossidium pedatum Looss, 1899 (J–L) collected from Clarias gariepinus in the Okavango Delta: (A) whole mount; (B) genital pore; (C) vitellaria,ovary and testes; (D) adults attached to urinary bladder; (E) whole mount; (F) body surface with papillae; (G) genital pore; (H) genital pore and pars prostatica; (I) vitellaria, ovary, uterus and testes; (J) whole mount; (K) anterior and posterior testes; (L) acetabulum and cirrus sac. Scale bars: A – 1 mm; B–D, H – 0.1 mm; E, I, K, L – 0.05 mm; J – 0.5 mm; F – 2 µm; G – 20 µm.