[The oncomiricidium of Diplozoon nipponicum Goto, 1891. A new type of larval haptor for the genus Diplozoon (Monogenea, Discocotylidae)].

Diplozoon nipponicum Goto 1891, a branchial parasite of Cyprinus carpio is mentioned for the first time in France and Western Europe. Carps, along with their Monogenea, were introduced from Hungary. After being obtained experimentally, the oncomiracidium is thoroughly studied (excretory system, ciliated cells, chaetotaxy, haptor). A new haptor for the genus Diplozoon is described: two pairs of larval lateral hooklets are present. The taxonomic and phylogenic implications of these observations are discussed for Diplozoon and Discocotylidae. Mainly as a result of the study of the haptor and the egg structure, it appears that two groups occur, the taxonomic and evolutive significance of which are to be discussed in Diplozoon.