Phyllodistomum bavuri Boomker, 1984

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 : 436-438

Phyllodistomum bavuri Boomker, 1984

Figs 1C , 3A–C ; Table 1

Phyllodistomum bavuri: Boomker 1984: 129–130 , fig. 1.

Redescription:

Body aspinose, ampullate in shape ( Fig. 1C ). Anterior part subcylindrical, amounts to ⅓ total body length. Posterior part of body thin, flattened dorsoventally, various internal structures microscopically visible without staining ( Fig. 3A ). Oral sucker round, situated subventrally. Acetabulum circular, larger than oral sucker, situated just posterior to junction of anterior end of hind body ( Fig. 1C ). Pharynx absent. Oesophagus short. Caecal bifurcation nearer to oral sucker than to acetabulum. Intestinal caeca terminate almost at end of posterior body margin. Excretory vesicle, excretory pore indistinct. Genital pore lies in midline of body halfway between oral and ventral suckers beneath gut bifurcation, in some specimens slightly more towards oral sucker ( Fig. 3B ). Cirrus sac absent. Two fairly large testes, deeply and irregularly lobed lying in middle of body on either side of midline between intestinal caeca. In some specimens testes slightly displaced one in front of other but mostly opposed ( Fig. 3C ). Ovary trilobed, sometimes round; situated to right of body midline in three specimens, to left in five specimens, between vitellarium and testes. Vitellarium compact, roughly round to lobed, opposed, lies just posterior to rim of acetabulum, anterior to ovary. Uterus consists of numerous loops, runs between testes and vitellarium to reach genital pore, loops rarely extend laterally beyond caeca ( Fig. 3C ). Uterine loops full of eggs. Eggs rounded to oval.

Material examined: BOTSWANA: 8 adult specimens, Okavango Delta, Shakawe mainstream (18°26'05.0''S 21°54'23.0''E) .

Site of infection: Urinary bladder.

Prevalence of infection: 2.3%.

Remarks: According to Boomker (1984) and Brooks and MacDonald (1986), species in the genus can mainly be distinguished from each other by the position of the ovary relative to the vitellarium, i.e. lying anterior, opposite or posterior to the vitellarium.

The species from the present study resembles Ph. linguale occurring in the urinary bladder of G. niloticus from Sudan, in having similar body size, the ovary being irregularly lobed, uterine coils that seldom cross the intestinal caeca laterally and the ovary lies posterior to the vitellarium. It differs in that the caeca does not terminate a distance from the posterior margin and the intestinal bifurcation being closer to the oral sucker in this species. The genital pore in Ph. linguale lies between the gut bifurcation and rim of the ventral sucker, while in our specimens it is halfway between the bifurcation and the ventral sucker.

The studied material also resembles Ph. bavuri described by Boomker (1984) from the urinary bladder of C. gariepinus from the Bangu River, Transvaal (presently Gauteng), in having the same body size and shape, the ovary being round to weakly trilobed and the vitellarium also being weakly lobed. It differs in that the gut bifurcation occurs near to the oral sucker and not halfway between the oral and ventral suckers. It also differs in that the intestinal caeca terminate close to the posterior margin of the body. The general morphology and measurements of specimens from the present material correspond to a certain degree with those in Ph. bavuri as described by Boomker (1984). However, in contrast to data by Boomker (1984), the present specimens show more variation in ovary shape, and vitellarium being slightly more lobed and irregularly shaped.

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