First-stage larvae of camallanid nematodes Procamallanus (Procamallanus) laeviconchus (Wedl, 1862) and Procamallanus (Procamallanus) sp. from naturally infected Distichodus niloticus (Hasselquist) and Clarias gariepinus (Burchell), respectively, from Lake Turkana, Kenya (new geographical records) are described, being for the first time studied by scanning electron microscopy. Larvae of both species are characterised by the presence of a dorsal cephalic tooth, four submedian cephalic papillae and a pair of amphids, and by the elongate tail with several terminal digit-like processes. The latter formations probably serve for the attachment of larvae to the substrate in water when the larvae attract copepod intermediate hosts by their movements; these structures, especially their numbers, may be of taxonomic importance in camallanid nematodes. The nematode genus Procamallanus Baylis, 1923 contains many species parasitizing freshwater, brackish-water and marine fishes and, less often, amphibians. The following five subgenera of Procamallanus were recognised by Moravec and Thatcher (1997) (see also Gibbons 2010): Procamallanus Baylis, 1923, Spirocamallanus Olsen, 1952, Spirocamallanoides Moravec et Sey, 1988, Punctocamallanus Moravec et Scholz, 1991 and Denticamallanus Moravec et Thatcher, 1997. Of them, only representatives of Procamallanus and Spirocamallanus are known from the African continent (totally 7 species), whereby P. (P.) laeviconchus (Wedl, 1862) (the type species of the genus) has so far been the only species of the former subgenus reported from freshwater fishes in Africa. This is also the only African Procamallanus species in which the life cycle has hitherto been studied and the first-stage larvae described (Moravec 1975). While redescribing P. laeviconchus from Synodontis spp. (congeneric with its type host) in Botswana (including SEM study), Moravec and Van As (2004) drew attention to the fact that this species was reported from about 30 fish species belonging to seven families and the specimens often exhibited morphological differences; they considered the presence of an unusually lobed circumoral flange a characteristic feature of P. laeviconchus, already illustrated by Wedl (1862) in the original description.

Department of Botany and Zoology Faculty of Science Masaryk University Brno

Institute of Parasitology Biology Centre of the Academy of Sciences of the Czech Republic České Budějovice

Institute of Vertebrate Biology Academy of Sciences of the Czech Republic Brno

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