Liesl L. Van As

A new species of Chonopeltis (Crustacea: Branchiura) from the southern Rift Valley, with notes on larval development

A new branchiurian, Chonopeltis lisikili n. sp., is described from material collected on squeakers (Synodontis spp.) in the Eastern Caprivi, Namibia and Okavango Delta, Botswana. The description is based on investigations of larval stages, ranging from the first instar to sub-adults females with eggs in the uteri, sub-adults and a young male.

Procamallanus (Procamallanus) spp. (Nematoda: Camallanidae) in fishes of the Okavango River, Botswana, including the description of P. (P.) pseudolaeviconchus n. sp. parasitic in Clarias spp. (Clariidae) from Botswana and Egypt

Parasitological dissections of fishes from the Okavango River, Botswana, revealed the presence of nematodes of the subgenus Procamallanus (Procamallanus) Baylis, 1923 in five fish species belonging to three different families. Based on light and scanning electron microscopical examinations, they proved to represent one previously known and one new species, i.e. P. (P.) laeviconchus (Wedl, 1861) from Synodontis nigromaculatus Boulenger, S. thamalakanensis Fowler (new host) (both Mochokidae) and Schilbe intermedius Rüppel (new host) (Schilbeidae), and P. (P.) pseudolaeviconchus n. sp. from Clarias stappersi Boulenger and C. theodorae Weber (both Clariidae). Specimens of the new species previously collected from Clarias gariepinus (Burchell) (type-host) in Egypt were also examined. Both of these nematode species are very similar, differing from each other mainly in the shape of the circumoral flange, which is conspicuously lobed in P. laeviconchus and unlobed in P. pseudolaeviconchus. Previously, these two species have been confused in the literature under the name P. laeviconchus. A key to Procamallanus (Procamallanus) spp. parasitising freshwater fishes in Africa, including Madagascar, is provided.

Procamallanus (Spirocamallanus) spp. (Nematoda: Camallanidae) from fishes of the Okavango River, Botswana, including P. (S.) serranochromis n. sp. parasitic in Serranochromis spp. (Cichlidae).

Three species of Procamallanus (Spirocamallanus) Baylis, 1923 (Camallanidae) (Nematoda: Camallanidae) were found in the digestive tract of freshwater fishes from the Okavango River, Botswana, i.e. P. (S.) daleneae (Boomker, 1993) from Synodontisvanderwaali Skelton & White (Mochokidae), P. (S.) spiralis Baylis, 1923 from Clariasstappersi Boulenger, C. theodorae Weber (both Clariidae) and Hepsetus odoe (Bloch) (Hepsetidae), and P. (S.) serranochromis n. sp. from Serranochromis macrocephalus (Boulenger) (type-host), S. angusticeps (Boulenger) and S. robustus (Günther) (all Cichlidae). All findings of the two previously known species represent new host records. The specimens were studied using both light and scanning electron microscopy. Spirocamallanus mazabukae Yeh, 1957 is considered a junior synonym of P. (S.) spiralis. A key to the species of Procamallanus (Spirocamallanus) parasitising fishes of continental Africa is provided.

Studies on ascaridid, oxyurid and enoplid nematodes (Nematoda) from fishes of the Okavango River, Botswana

Based on light and scanning electron microscopical studies, eight species (five adult and three larval) of nematodes belonging to the Ascaridida, Oxyurida and Enoplida were collected from fishes of the Okavango River, Botswana, namely Falcaustra similis Moravec et Van As, 2004, Atractidae gen. sp. (only female) (both Cosmocercoidea), Cucullanus sp. (only female) (Seuratoidea), Cithariniella longicaudata sp. n., Synodontisia annulata sp. n. (both Oxyuroidea), Contracaecum sp. third-stage larvae, third-stage larvae of Galeiceps sp. (both Ascaridoidea) and Eustrongylides sp. fourth-stage larvae (Dioctophymatoidea). The new species Citharinella longicaudata (type host Schilbe intermedius Rüppel) is mainly characterised by the shape and size of cephalic papillae and the spicule 108 µm long, and Synodontisia annulata (type host S. intermedius) by the shape of cephalic papillae, body length of gravid females (4.88-5.33 mm) and a short spicule (66 µm long). The female specimen of Cucullanus sp. from Tilapia sparmanni Smith markedly differs from congeners parasitising inland fishes in Africa by the elongate pseudobuccal capsule and by the excretory pore far posterior to the oesophago-intestinal junction; apparently, it belongs to an undescribed species. Galeiceps larvae parasitising fishes are described for the first time. Cithariniella gonzalezi Van Waerebeke, Chabaud, Bain et Georges, 1988 is considered a junior synonym of C. khalili Petter, Vassiliadès et Troncy, 1972, and the previous records of Cithariniella citharini Khalil, 1964 from Synodontis spp. in Egypt concern, in fact, Cithariniella khalili Petter, Vassiliadès et Troncy, 1972. The specimens of Cithariniella reported by Koubková et al. (2010) from Paradistichodus dimidiatus (Pellegrin) in Senegal and misidentified as C. gonzalesi Van Waerebeke, Chabaud, Bain et Georges, 1988 are considered to represent a new species, C. koubkovae sp. n.; this is established by reference to the description and drawings provided by Koubková et al. (2010).

First record of Chonopeltis inermis Thiele, 1900 (Crustacea: Branchiura) in the Limpopo River system with notes on its morphology.

Specimens of Chonopeltis collected from the gill chambers of the snake catfish Clarias theodorae in the Luphephe River, a tributary of the Limpopo in northern Transvaal, showed close resemblance to C. inermis Thiele, 1900 previously only recorded from Lake Malawi. Comparative scanning electron microscopical studies on this material and specimens of C. inermis on loan from The Natural History Museum, London showed beyond doubt that C. inermis also occurs in the Limpopo System. This implies that it dispersed across a watershed and successfully established in a different water system.

Studies on some spirurids (Nematoda: Spirurida) from fishes of the Okavango River, Botswana

Based on light and scanning electron microscopical studies, three adult spirurid nematode species, Camallanus (Zeylanema) ctenopomae Vassiliadès & Petter, 1972, Paracamallanus cyathopharynx (Baylis, 1923) (both Camallanidae) and Spinitectus polli Campana-Rouget, 1961 (Cystidicolidae), are redescribed from specimens collected in fishes of the Okavango River, Botswana: C. (Z.) ctenopomae from Ctenopoma sp. (Anabantidae), P. cyathopharynx from Clariasstappersi Boulenger, C. theodorae Weber (both new hosts, Clariidae) and C. gariepinus (Burchell), as well as S. polli from Synodontis nigromaculatus Boulenger (new host, Mochokidae). Moreover, spirurid larvae of an additional three species were found in fishes from the same locality: Rhabdochona paski Baylis, 1928 fourth-stage larva (Rhabdochonidae) in S. nigromaculatus (Mochokidae), Physalopteridae gen. sp. 1 third-stage larva in C. gariepinus (Clariidae) and Physalopteridae gen. sp. 2 third-stage larva in Serranochromis angusticeps (Boulenger) (Cichlidae), all representing new host and geographical records. Spinitectus zambezensis Boomker, 1993 is considered a junior synonym of S. polli.

Argulus izintwala n. sp. (Crustacea: Branchiura) from Lake St Lucia, South Africa.

During surveys of the fish parasites of Lake St Lucia on the coast of northern KwaZulu-Natal, specimens of an hitherto undescribed argulid were found on the skin of the kelee shad Hilsa kelee (Cuvier). This, only the fourth argulid species to be found in South African coastal waters, is here described as Argulus izintwala n. sp.During surveys of the fish parasites of Lake St Lucia on the coast of northern KwaZulu-Natal, specimens of an hitherto undescribed argulid were found on the skin of the kelee shad Hilsa kelee (Cuvier). This, only the fourth argulid species to be found in South African coastal waters, is here described as Argulus izintwala n. sp.

Redescription of Argulus multipocula Barnard, 1955 (Crustacea: Branchiura) collected on the west coast of SouthAfrica

Argulus multipocula Barnard, 1955 was originally described from a single female found in a littoral sample from the east coast of South Africa. We present a redescription of this species based on light and scanning electron microscope studies of 25 females collected from the southern mullet Liza richardsonii (Smith) on the west coast of South Africa.

Pathology of eyes and brain of fish infected with diplostomids, southern Africa

Only a few reports exist on diplostomid metacercariae found in southern African fish and even less information is available on the pathology associated with these infections. During surveys conducted in December 2008 and August 2010, different fish species were collected from the Okavango (Botswana) and Orange—Vaal (South Africa) River Systems. Histological sections were done from intact Tilapia sparrmanii A. Smith, 1840 and Coptodon rendalli (Boulenger, 1896) eyes and the brains of infected Brycinus lateralis (Boulenger, 1900) in order to determine the precise site of infection and the possible pathological effects. It was found that the encapsulated diplostomids from the eyes of the infected haplotilapiine species from the Okavango System caused localised retinal and/or choroid detachments. No pathological effects were observed in the histological sections of the brains of B. lateralis that were infected with diplostomids, except for the presence of red blood or rodlet cells. Tilapia sparrmanii collected from the Orange River were not infected with diplostomids.

Ecology of Diplostomid (Trematoda: Digenea) Infection in Freshwater Fish in Southern Africa

The complex life cycles of most trematode parasites include three hosts. The first intermediate host is a snail, the second is normally a teleost fish and a piscivorous bird serves as the definitive host. Lymnaeid snails are most likely to be responsible for cercarial shedding, which infect exposed fish and in turn are eaten by piscivorous birds. From 2008 to 2010 fish in the Okavango and Orange-Vaal River Systems were collected and dissected in order to determine the prevalence and intensity of larval trematode infections in the eyes and brains. This paper discusses the possible ecological factors which can influence the probability of certain fish species becoming infected with diplostomid cercariae and hence metacercariae. The feeding strategies and sizes of piscivorous birds, which could act as definitive hosts for the adult worms, are summarized and discussed. Information on the snail species responsible for furcocercous cercarial shedding in the two study sites is also included.