As an adult, Eustrongylides ignotus, recognized as a zoonotic parasite, is a parasitic nematode f... more As an adult, Eustrongylides ignotus, recognized as a zoonotic parasite, is a parasitic nematode found in the gastrointestinal tract of fish-eating birds. As larvae, they are found in the connective tissue or body cavities of freshwater fish. In Japan, E. ignotus and E. tubifex have been found in three avian species, but their distribution in intermediate and paratenic hosts remains unclear. For this study, 16 commercial raw Japanese smelts, Hypomesus transpacificus nipponensis, were used for parasitological examination. A pinkish red worm collected from the abdominal wall of one smelt (6.3%) was identified as E. ignotus based on the high sequence similarity (99.9%) of the partial 18S ribosomal RNA gene and the morphology of its cephalic and caudal ends. Furthermore, a Raphidascaris-like nematode was found in the intestines of five smelts examined (31.3%) and was identified as R. gigi in view of the absence of lateral cuticular alae. Eustrongylides ignotus and R. gigi have been reported in various freshwater fish, but not in smelts. Therefore, this finding of E. ignotus and R. gigi in H. transpacificus nipponensis represents a new host record.
A redescription is given of Raphidascaris gigi Fujita, 1928 based on newly collected specimens fr... more A redescription is given of Raphidascaris gigi Fujita, 1928 based on newly collected specimens from the intestine of masu salmon Oncorhynchus masou (Brevoort) in the Kinu River in Japan. The species is characterised by the absence of interlabia and lateral alae, by the presence of lips without lateral membranous flanges and by numerous pre-anal and postanal papillae in the male. Although the general morphology of this species resembles that of Ichthyascaris spp. as defined by Bruce (1990), who transferred R. biwakoensis (= R. gigi) to this genus, the absence of the alae uniting close the ventrolateral lips shows clearly that it belongs to Raphidascaris Railliet & Henry, 1915. Ichthyascaris Wu, 1949 is here considered a subgenus of Raphidascaris, and two species described in the former genus are transferred to the latter as R. gymnocraniae (Bruce, 1990) n. comb. and R. sillagoides (Bruce, 1990) n. comb. The finding of R. gigi in O. masou represents a new host record.
As an adult, Eustrongylides ignotus, recognized as a zoonotic parasite, is a parasitic nematode f... more As an adult, Eustrongylides ignotus, recognized as a zoonotic parasite, is a parasitic nematode found in the gastrointestinal tract of fish-eating birds. As larvae, they are found in the connective tissue or body cavities of freshwater fish. In Japan, E. ignotus and E. tubifex have been found in three avian species, but their distribution in intermediate and paratenic hosts remains unclear. For this study, 16 commercial raw Japanese smelts, Hypomesus transpacificus nipponensis, were used for parasitological examination. A pinkish red worm collected from the abdominal wall of one smelt (6.3%) was identified as E. ignotus based on the high sequence similarity (99.9%) of the partial 18S ribosomal RNA gene and the morphology of its cephalic and caudal ends. Furthermore, a Raphidascaris-like nematode was found in the intestines of five smelts examined (31.3%) and was identified as R. gigi in view of the absence of lateral cuticular alae. Eustrongylides ignotus and R. gigi have been reported in various freshwater fish, but not in smelts. Therefore, this finding of E. ignotus and R. gigi in H. transpacificus nipponensis represents a new host record.
A redescription is given of Raphidascaris gigi Fujita, 1928 based on newly collected specimens fr... more A redescription is given of Raphidascaris gigi Fujita, 1928 based on newly collected specimens from the intestine of masu salmon Oncorhynchus masou (Brevoort) in the Kinu River in Japan. The species is characterised by the absence of interlabia and lateral alae, by the presence of lips without lateral membranous flanges and by numerous pre-anal and postanal papillae in the male. Although the general morphology of this species resembles that of Ichthyascaris spp. as defined by Bruce (1990), who transferred R. biwakoensis (= R. gigi) to this genus, the absence of the alae uniting close the ventrolateral lips shows clearly that it belongs to Raphidascaris Railliet & Henry, 1915. Ichthyascaris Wu, 1949 is here considered a subgenus of Raphidascaris, and two species described in the former genus are transferred to the latter as R. gymnocraniae (Bruce, 1990) n. comb. and R. sillagoides (Bruce, 1990) n. comb. The finding of R. gigi in O. masou represents a new host record.
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