A Checklist of the Parasites of Eels (Anguilla spp.) (Anguilliformes: Anguillidae) in Japan (1915-2007)

1915～2007年の93年間に出版された文献に基づき, 日本産ウナギ属魚類3種(ウナギAnguilla japonica, オオウナギAnguilla marmorata, ヨーロッパウナギAnguilla anguilla)の寄生虫に関する情報を2つのリスト(寄生虫-宿主リスト, 宿主-寄生虫リスト)に整理して目録を作成した。ウナギとオオウナギは在来種であり, ヨーロッパウナギは国外からの移入種である。本目録には, 44種の寄生虫(繊毛虫類6種, 微胞子虫類1種, ミクソゾア類6種, 吸虫類7種, 単生類7種, 条虫類3種, 線虫類7種, 鉤頭動物4種, ヒル類2種, カイアシ類1種)に加えて, 学名がまだ決定していない寄生虫の情報が含まれる。寄生虫-宿主リストでは, 各寄生虫は高位分類群ごとに配列され, 最新の学名, シノニム, 寄生部位, 地理的分布および報告者の情報が示されている。上記44種のうち, ウナギから43種, オオウナギから1種, ヨーロッパウナギから10種の寄生虫が報告されている。単生類のGyrodactylus anguillaeと線虫類のRaphidascaris acusはヨーロッパウナギとともにヨーロッパから, またGyrodactylus nipponensisもインド・西太平洋地域から持ち込まれたと推察されている。ウナギから報告された寄生虫のうち, 8種は海産または汽水産で, 2種(Tubulovesicula anguillae, Pseudodactylogyrus kamegaii)の成虫がウナギに特異的に寄生しているため, 海洋と汽水域において, ウナギはそれら寄生虫の固有宿主の役割を果たしていると言える。

Information on the protistan and metazoan parasites of three species of eels, the Japanese eel Anguilla japonica, the giant mottled eel A. marmorata and the European eel A. anguilla, in Japan is summarized in the Parasite-Host List and Host-Parasite lists, based on the literature published for 93 years between 1915 and 2007. Both A. japonica and A. marmorata are native to Japan, whereas A. anguilla is an introduced species from Europe. The parasites, including 44 named species and those not identified to species level, are listed by higher taxon as follows: Sarcomastigophora (no named species), Ciliophora (6), Microspora (1), Myxozoa (6), Trematoda (7), Monogenea (7), Cestoda (3), Nematoda (7), Acanthocephala (4), Hirudinida (2), and Copepoda (1). For each taxon of parasite, the following information is given: its currently recognized scientific name, any original combination, synonym(s), or other previous identification used for the parasite occurring in eels; habitat (freshwater, brackish, or marine); site(s) of infection within or on the host; known geographical distribution in Japanese waters; and the published source of each locality record. Of the 44 named species of parasites, 43 are from A. japonica, 1 from A. marmorata, and 10 from A. anguilla. Gyrodactylus anguillae (Monogenea) and Raphidascaris acus (Nematoda) are the exotic species that were probably introduced on A. anguilla from Europe, and it has also been suggested that G. nipponensis (Monogenea) was introduced on eels imported from somewhere in the Indo-western Pacific. Of the parasites recorded from A. japonica, eight species are marine and/or brackish-water species, of which two (i.e., Tubulovesicula anguillae, Pseudodactylogyrus kamegaii) are host-specific and occur as adults. This indicates that A. japonica serves as the definitive host for these parasites in marine and/or brackish waters where the host species constatntly remains.