Eustrongylides sp.

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 : 19

Eustrongylides sp. fourth-stage larvae Fig. 15

Hosts: Amur catfish, Silurus asotus ( Siluridae , Siluriformes ), and snakehead, Channa argus ( Channidae , Perciformes ).

Sites of infection: Mesentery ( S. asotus ), and body cavity and mouth cavity ( C. argus ).

Localities: Kurose River, Higashi-Hiroshima, Hiroshima Prefecture ( S. asotus ) (no data on sampling date), Kamo River (a tributary of the Ashida River), Fukuyama, Hiroshima Prefecture (collected 26 November 2008) and Lake Shinji, Mat- sue, Shimane Prefecture (collected 16 September 2009) (both C. argus ), all Honshu, Japan.

Prevalence and intensity: S. asotus : no data on prevalence; 17 nematodes. C. argus: Kamo R. : 1 fish infected, 61.5 cm TL/1 fish examined; 2 nematodes; and L. Shinji: 1 fish infect- ed, 90.0 cm TL/ 1 fish examined; 1 nematode.

Deposition of voucher specimens: IPCAS N–76.

Remarks. Larvae of Eustrongylides Jägerski ̂ld, 1909 from fishes and some other aquatic vertebrates, serving as paratenic hosts, are unidentifiable to species by morpho- logical features ( Measures 1988). Adults of this genus are parasites of the proventriculus of fish-eating birds. Eustrongylides larvae in Japan have already been reported from Rhinogobius similis Gill , Rhinogobius sp. (both Gobiidae ) and Channa argus ( Channidae ) ( Yamaguti 1941, Shimazu et al. 2000). Currently, based on molecular and morphological studies, a pinkish worm from the abdominal wall of the Japanese smelt Hypomesus nipponensis McAllister (reported as H. transpacificus nipponensis ) ( Osmeridae ) caught in Lake Biwa, Shiga Prefecture, Honshu, was identified as a larva of Eustrongylides ignotus Jägerski ̂ld, 1909 (see Abe 2011). In this study, one specimen of Eustrongylides sp. was found in the mouth cavity of C. argus , which probably resulted from the migration from the body cavity after the fish was dead.

Figures

Fig. 15. Eustrongylides sp. larva from Channa argus (Cantor), scanning electron micrographs of cephalic end. A – apical view; B – sublateral view. Abbreviations: a – cephalic papillae of inner circle; b – cephalic papillae of outer circle; c – mouth opening.