Based on light and scanning electron microscopical studies, two new species of nematode parasites are described from freshwater fishes in Thailand: Orientatractis mekongensis n. sp. (Atractidae) from the intestine of Pangasius bocourti Sauvage (type-host) and Helicophagus leptorhynchus Ng & Kottelat (both Pangasiidae, Siluriformes), and Neosynodontisia suratthaniensis n. sp. (Pharyngodonidae) from the intestine of Labiobarbus siamensis (Sauvage) (Cyprinidae, Cypriniformes), for which a new genus Neosynodontisia n. g. is established. Orientatractis mekongensis is mainly characterised by the number and distribution of caudal papillae (2 preanal, 1 adanal and 5 postanal pairs), the length of the left spicule (306-384 µm) and large body sizes (length of males and gravid females 5.4-6.7 mm and 7.8-9.0 mm, respectively). Neosynodontisia differs from other pharyngodonid genera with representatives parasitic in fishes not only by some morphological features (mouth withdrawn into the cephalic end with inflated cuticle, structure of the male caudal end, filamented eggs), but mainly by the occurrence of males inside the body of females. A key to the genera of the Pharyngodonidae with representatives parasitising fishes is provided.

• MeSH
• Species Specificity MeSH
• Nematoda anatomy & histology   classification   ultrastructure   MeSH
• Microscopy, Electron, Scanning MeSH
• Fresh Water MeSH
• Catfishes parasitology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Thailand MeSH

The oxyuroid nematode Ichthyouris bursata Moravec & Prouza, 1995 (Pharyngodonidae) was recorded from the intestine of discus (Symphysodon spp. and hybrids) cultured in discus farms in Bangkok and Nonthaburi, central Thailand, during 2006 and 2007. This material made it possible to study in detail the morphology of this little known parasite species, using both light and scanning electron microscopy (the latter not previously used for the male). The SEM examination showed taxonomically important morphological features not previously reported or erroneously described, including the presence of three bilobed lips, a pair of sclerotised plate-like structures and a median cone-shaped outgrowth on the posterior cloacal lip, short 'hairs' on the cloacal lips, digital phasmids in the male and, sometimes, up to two filaments on the egg poles. This species is of South American origin, which was confirmed by its recent record from a free-living blue discus S. aequifasciatus Pellegrin in Brazil. The reproduction and transmission of I. bursata in the conditions of aquarium tanks is probably permitted by the direct (homoxenous) life-cycle of this parasite.

• MeSH
• Cichlids parasitology   MeSH
• Animals, Wild MeSH
• Oxyurida Infections parasitology   veterinary   MeSH
• Fish Diseases parasitology   MeSH
• Oxyurida classification   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Five nematode species were recorded from the stomach and rectum of the spotted squeaker Synodontis nigromaculatus Boulenger or the finetooth squeaker S. vanderwaali Skelton & White (Mochokidae, Siluriformes) from the Okavango River, Botswana: Falcaustra similis n. sp. (Kathlaniidae), Labeonema africanum n. sp. (Cosmocercidae), Synodontisia okavangoensis n. sp. (Pharyngodonidae), Procamallanus ( Procamallanus ) laeviconchus (Wedl, 1861) (Camallanidae) and Spinitectus sp. (Cystidicolidae) (only a single female). F. similis (type-host Synodontis nigromaculatus ) differs from the similar species F. straeleni Campana-Rouget, 1961 mainly by the number and disposition of the male caudal papillae and the structure of the mouth; L. africanum (type-host S. nigromaculatus ) differs from its congeners in having distinctly longer spicules (105-120 microm), a relatively shorter gubernaculum (30-36 microm) and in the number and arrangement of the male caudal papillae; Synodontisia okavangoensis (type-host Synodontis nigromaculatus ) is characterised principally by crescent-shaped cephalic papillae, length (87 microm) and shape of the spicule as well as large eggs (0.156-0.180x69-102 microm). Synodontisia moraveci Anderson & Lim, 1996 is transferred to a newly established genus, Royandersonia n. g., (as its type-species) as R. moraveci (Anderson & Lim, 1996) n. comb. Some taxonomic problems concerning Procamallanus ( P .) laeviconchus are discussed. All species were studied by scanning electron microscopy for the first time.

• MeSH
• Species Specificity MeSH
• Nematoda anatomy & histology   classification   MeSH
• Microscopy, Electron, Scanning MeSH
• Fishes parasitology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Botswana MeSH