Rhabdochona zacconis Yamaguti, 1935

Moravec, František & Nagasawa, and Kazuya, 2018, Rhabdochona angusticaudata sp. n. (Nematoda: Rhabdochonidae) from the Japanese eel Anguilla japonica, and new records of some other nematodes from inland fishes in Japan, Folia Parasitologica (016) 65, pp. 1-22 : 14-15

Rhabdochona zacconis Yamaguti, 1935 Fig. 11

Syn.: Rhabdochona marinum Roytman, 1963 .

Host: Big-scaled redfin, Tribolodon hakonensis ( Cyprinidae , Cypriniformes ).

Site of infection: Intestine.

Locality : Takahara River (a tributary of the Jinzu River ), Hida, Gifu Prefecture, Honshu, Japan (collected 1 June 2009) .

Prevalence and intensity: 13% (3 fish infected, 16.0– 19.4 cm TL/23 fish examined, 14.0– 21.8 cm TL); 1–5 (mean 2) nematodes per fish.

Deposition of voucher specimens: IPCAS N-38.

Remarks. The morphology of the present specimens is in full agreement with the redescription of R. zacconis provided by Moravec (1975) and Moravec et al. (1981), based on LM examination of specimens from the same host species ( T. hakonensis ) in Japan. Therefore, we refrain from describing these nematodes. However, the SEM study, used for the first time in this species, made it possible to confirm some features (e.g. cephalic papillae, amphids, arrangement of anterior prostomal teeth, presence of sublabia, shape of deirids, distribution of genital papillae) that are not easily visible using LM ( Fig. 11 ).

Rhabdochona zacconis is known to be distributed in Japan, eastern Russia and western Canada, parasitising cypriniform fishes of the genera Catostomus Lesueur (Catostomidae) , Tribolodon Sauvage and Zacco Jordan et Evermann (both Cyprinidae ) ( Moravec 1975, Moravec et al. 1981, Arai and Mudry 1983, Arai and Smith 2016). In Japan, this parasite was previously recorded by Yamaguti (1935) from Zacco platypus (Temminck et Schlegel) in Nagano Prefecture, Honshu, by Moravec et al. (1981) from T. hakonensis and Z. platypus in Hokkaido (Lakes Akan and Shikotsu [reported erroneously as Chitose, see Nagasawa 2017] and Chihase River) and Honshu (Lake Biwa) (see also Moravec 1975), by Moravec and Nagasawa (1989) from T. hakonensis from several localities in Hokkaido and Honshu, and by Moravec et al. (1998) from T. hakonensis in the Okitsu River, Shizuoka Prefecture, Honshu, where they studied the seasonal maturation cycle of R. zacconis in this host. This parasite was recorded from eastern Russia (Sea of Japan, Putiyatin Island) and reported by Russian authors as Rhabdochona denudata (Dujardin, 1845) or as R. marinum from Tribolodon brandtii (Dybowski) (see Moravec 1975). Rhabdochona zacconis was also reported from Catostomus macrocheilus Girard in British Columbia, western Canada ( Arai and Mudry 1983, Arai and Smith 2016).

Figures

Fig. 11. Rhabdochona zacconis Yamaguti, 1935 from Tribolodon hakonensis (Günther), scanning electron micrographs. A, B – cephalic end of male, subapical and apical views, respectively (arrows indicate sublabia); C – deirid; D – tail of male, lateral view (arrow indicates cloaca); E – eggs dissected out from uterus; F – eggs with polar filaments. Abbreviations: a – cephalic papilla; b – amphid.