Phyllodistomum vanderwaali Prudhoe & Hussey, 1977

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 : 438-440

Phyllodistomum vanderwaali Prudhoe & Hussey, 1977

Figs 1D , 3D–I ; Table 1

Phyllodistomum vanderwaali: Prudhoe & Hussey 1977: 116–119 , fig. 2; Boomker 1984: 131, fig. 7.

Redescription:

Body ampullaceous with subcylindrical forebody and leaf-like dorsoventrally flattened hindbody ( Figs 1D , 3E ). Forebody constitutes ¼ of total length, hindbody almost circular. Body surface unspined, papillae present on the lateral sides of body ( Fig. 3F ). Oral sucker terminal, almost round. Acetabulum circular, larger than oral sucker, situated at anterior level of hindbody ( Figs 1D , 3F ). Pharynx absent. Oesophagus short. Caecal bifurcation immediately posterior to oral sucker, terminating near posterior body margin. Excretory pore opens dorsally near posterior extremity of body. Genital pore opens halfway between gut bifurcation and acetabulum ( Fig. 3G, H ). No cirrus sac, terminal organs of male and female complexes lie free in parenchyma. Ejaculatory duct short, runs from genital pore to open into small pars prostatica, which is endowed with a large number of deeply staining gland-cells ( Fig. 3H ). Two indented, irregularly lobed testes situated on either side of median line of mid region of body in between intestinal caeca, may lie opposite each other or one slightly in front of other ( Fig. 3I ). Ovary lies to right of median line in six specimens; to left in other six specimens, but always in front of testes and posterior to vitellarium. Ovary irregularly round or lobed mass ( Fig. 3I ). Vitellarium compact diagonally opposed bodies, lie posterior to rim of acetabulum, anterior to ovary between intestinal caeca ( Fig. 3I ). Uterus consists of numerous loops that pass anteriorly along the median line between testes and vitelline bodies to reach genital pore, may extend beyond ends of caeca occasionally crossing caeca laterally ( Fig. 1D ). Uterus contains thin-shelled oval eggs. Eggs larger towards the distal end.

Material examined: BOTSWANA: 12 adult specimens, Okavango Delta, 7 Xaro mainstream (18°25'19.7''S 21°56'19.9''E); 5 Xaro lagoon (18°25'19.7''S 21°56'19.9''E) .

Site of infection: Numerous worms observed in urinary bladder ( Fig. 3D ).

Prevalence of infection: 4.7%.

Remarks: This species differs from Ph. spatula , Ph. symmetrorchis and Ph. ghanense in having the ovary not anterior or slightly posterior to the vitellarium. It also differs from Ph. ghanense in having the uterine coils not filling the entire posterior two-thirds of the body. In Ph. spatula the ovary is completely round, while in Ph. spatulaeforme the ovary is kidney-shaped and the testes are small in relation to the body size.

Ph. vanderwaali differs from Ph. linguale and Ph. bavuri in being much smaller and in having the vitellarium immediately posterior of the acetabulum and the intestine bifurcating almost immediately posterior of the oral sucker. It also differs from Ph. bavuri , as redescribed in this paper, in that the testes, ovary and vitellarium are different in shape and size, the ovary lies more adjacent to the vitellarium and the body size is far smaller. The general morphology and measurements of specimens of the present material also correspond to a certain degree with Ph. vanderwaali as described by Prudhoe and Hussey (1977) and redescribed by Boomker (1984). However, in contrast to data by Prudhoe and Hussey (1977) and Boomker (1984), the present specimens show more variation in the shape, size and position of the testes, which in different specimens may be directly diagonal or nearly at the same level and dissimilar in size. Generally, the testes are larger than the ovary but in some specimens they are smaller.

All the above mentioned morphological differences are considered to be within the intraspecific variability of Ph. vanderwaali and therefore the specimens of the present material are assigned to this species. This is the first record of Ph. vanderwaali 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.