Re-examination of the syntypes of the capillariid nematode Neocapillaria phoxini Yu et Wang, 1994, the type species of Neocapillaria Yu et Wang, 1994, described from the intestine of the freshwater fish Phoxinus lagowskii variegatus Günther (Cyprinidae) from China, confirmed its morphological similarity with species of Freitascapillaria Moravec, 1987, to which it is transferred as Freitascapillaria phoxini (Yu et Wang, 1994) comb. n. Consequently, Neocapillaria Yu et Wang, 1994 (a homonym to Neocapillaria Moravec, 1987) and Sinocapillaria Moravec et Spratt, 1998 become junior synonyms of Freitascapillaria. Skrjabinocapillaria gigantea is transferred to Freitascapillaria as F. gigantea (Wang, 1984) comb. n.
Dracunculus globocephalus Mackin, 1927 (Nematoda: Dracunculoidea) is redescribed from specimens collected from the mesentery of the snapping turtle, Chelydra serpentina (L.), in Louisiana, USA. The use of scanning electron microscopy, applied for the first time in this species, made it possible to study details in the structure of the cephalic end and the arrangement of male caudal papillae that are difficult to observe under the light microscope. This species markedly differs from all other species of Dracunculus in having the spicules greatly unequal in size and shape, in the absence of a gubernaculum, and in the disposition of male caudal papillae. The validity of D. globocephalus is confirmed, but the above mentioned morphological differences are not sufficient for listing it in a separate genus. This is the first record of D. globocephalus in Louisiana.
The cystidicolid nematode Metabronema magnum (Taylor, 1925) is redescribed from specimens collected from the swimbladder of the fish (golden trevally) Gnathanodon speciosus (Forsskål) (Carangidae, Perciformes) off New Caledonia, South Pacific (a new geographical record). The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species. Its pseudolabia were found to possess distinct anterior protrusions (protuberances), sublabia are absent, only four cephalic papillae are present, deirids are bifurcated, and the male possesses six pairs of postanal papillae. By its morphology, M. magnum seems to be most similar to species of Salvelinema Trofimenko, 1962, also from the swimbladder of fishes, differing from them mainly in the presence of median wedge-shaped outgrowths in the mouth, lateral alae, the longer spicule on the right side, and a fewer number of pairs of preanal papillae in the male. Since the morphology of M. magnum considerably differs from that of other representatives of the Cystidicolidae, Metabronema in Rasheed's (1966) conception is considered a valid genus.
The nematode Rhabdochona anguillae Spaul, 1927, a specific intestinal parasite of the European eel, Anguilla anguilla (L.), is redescribed and illustrated from specimens collected from eels of the Sousa River, northern Portugal (prevalence 20%, intensity 2-13). The species is characterized by the presence of 14 anterior teeth in the prostom, small non-bifurcate deirids, absence of lateral preanal papillae, by the length (0.460-0.660 and 0.130-0.150 mm) and the shape of spicules, fairly large (0.041-0.054 x 0.025-0.030 mm) mature eggs without filaments, and by the bluntly pointed to rounded tip of the tail. Its morphological features are discussed in relation to other congeneric species. This nematode has hitherto been recorded only from eels in southern Europe (Portugal, Spain, Bulgaria).
Two little-known species of Spinitectus (Nematoda: Cystidicolidae) were, for the first time, recorded from fishes of the Lacantún River (Usumacinta River basin) in the Lacandon rain forest, Chiapas, southern Mexico: S. tabascoensis Moravec, García-Magaña et Salgado-Maldonado, 2002 in intestines of Ictalurus furcatus (Valenciennes) (Ictaluridae) (adults and juveniles), Cathorops aguadulce (Meek) and Potamarius nelsoni (Evermann et Goldsborough) (both Ariidae) (in both only juveniles), and S. osorioi Choudhury et Pérez-Ponce de León, 2001 in Atherinella alvarezi (Díaz-Pardo) (Atherinopsidae) (adults in intestine) and Eugerres mexicanus (Steindachner) (Gerreidae) (adults and juveniles in stomach). Eugerres mexicanus, C. aguadulce and P. nelsoni represent new host records. Detailed light and electron microscopical studies of S. tabascoensis revealed some taxonomically important, previously not observed features, such as cuticular spines arranged in four sectors, the cephalic structure, the number (2) of ventral precloacal ridges or the structure of the male caudal end. Therefore, Spinitectus tabascoensis is redescribed. Spinitectus macrospinosus Choudhury et Perryman, 2003, described from ictalurids in Canada and the USA, is considered its junior synonym. Spinitectus tabascoensis seems to be a specific parasite of Ictalurus spp., whereas C. aguadulce and P. nelsoni, as well as some other fishes, serve only as its paratenic hosts. The definitive hosts of S. osorioi are atherinopsid fish (A. alvarezi, Chirostoma spp.), whereas the gerreid E. mexicanus probably serves only as its postcyclic host.
The philometrid nematode, Philometra saltatrix Ramachandran, 1973, is redescribed from male and female specimens collected from the ovaries of the marine fish (bluefish) Pomatomus saltatrix (L.) (Pomatomidae, Perciformes) from the Tuscan Sea, Italy. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little known species. For the first time, the actual structure of the male cephalic and caudal ends is described. The male possesses 14 small cephalic papillae arranged in two circles, the spicules are 84-111 µm long and the gubernaculum, 75-84 µm long, has its distal portion provided with dorsal transverse lamella-like structures. The caudal end of subgravid females bears two very small, hardly visible lateral papilla-like projections. This is the first record of P. saltatrix, a species originally described from the West Atlantic, from the Tuscan Sea and the second one in the Mediterranean region.
Ascaridoid nematodes referable to Brevimulticaecum heterotis (Petter, Vassiliadès et Marchand, 1979) Khalil, 1984 were recorded from the intestine of the African bonytongue, Heterotis niloticus (Cuvier) (Arapaimidae, Osteoglossiformes), from the Mare Simenti in the Niokolo Koba National Park, East Senegal and from Kosti, Sudan. Their examination using light microscopy and for the first time both environmental scanning electron microscopy and scanning electron microscopy revealed some previously unreported morphological features and made possible a detailed redescription of this species. The most important finding is the presence of dentigerous ridges on the inner edges of the lips, which confirms the attribution of this species to Multicaecum Baylis, 1923, where it was originally placed, and not to Brevimulticaecum Mozgovoy in Skryabin, Shikhobalova et Mozgovoy, 1951 where it had subsequently been transferred. A key to Brevimulticaecum and Multicaecum species is provided. Multicaecum heterotis is the first species of the genus to be sequenced. Partial sequences of the small ribosomal subunit (18S) and internal transcribed spacer 2 region (ITS2) of nuclear ribosomal DNA (rDNA) have been analysed and compared with other nematode species.
A new nematode, Rhabdochona mexicana sp. n., is described based on specimens recovered from the intestine of two species of fishes, Astyanax mexicanus (De Filippi) (type host) and Astyanax J'asciatus (Cuvier) (Characidae: Characiformes) in central Mexico. This species is characterised by the following characters: 10 anteriorly directed teeth in the prostom, a larger (left) spicule which is slender in form with a small bifurcation at its distal tip covered by a culicular membrane, a smaller (right) spicule without a barb at its distal tip, eggs bearing an irregular flock-like coaling, and a conical tail without a cuticular spike (in both sexes).
Based on light and scanning electron microscopical studies, three new, one already known and one not identified species of the nematode genus Rhabdochona Railliet, 1916 are reported from the intestine of freshwater fishes in Dzanga-Sangha Protected Areas (Congo River basin), the Central African Republic: Rhabdochona (Rhabdochona) centroafricana sp. n. from Barbus miolepis Boulenger, R. (R.) marcusenii sp. n. from Marcusenius greshoffii (Schilthuis), R. (Globochona) paski Baylis, 1928 from Phenacogrammus aurantiacus (Pellegrin) (new host record), R. (G.) tricuspidata sp. n. from Raiamas christyi (Boulenger) and Rhabdochona (G.) sp. (only females) from Epiplatys multifasciatus (Boulenger). Rhabdochona centroafricana is mainly characterised by the length of the left spicule (333 µm) and the presence of the operculum bearing a conspicuous gelatinous formation on one of egg poles, R. marcusenii by the length of the left spicule (453-486 µm) and the presence of a single broad filament on one egg pole only and R. tricuspidata by the body with marked cuticular ornamentations and deirids branching into three prongs. A key to valid species of Rhabdochona parasitic in fishes of Africa is provided.