Fine structure of sporogonic stages of Goussia clupearum (Apicomplexa : Eimeriidae) in the liver of infected fish (Belone belone L.), using light andelectron microscopy

A coccidian species, Goussia clupearum (L.) is reported to parasitize the l iver of a new host. Belone helone (Teleostei: Belonidae), caught on the Atl antic coast at the north of Portugal. The parasitophorous vacuole containin g oocysts was attached to the host's liver cells. Spherical oocysts (simila r to 21.2 mum diameter), each containing four ellipsoidal elongated sporocy sts (10.5 x 6.3 mum), were enclosed in the parasitophorous vacuole. Each sp orocyst contained two sporozoites. The micropyle was absent, but a polar gr anule (without Stieda body) was present. Each sporozoite possessed four ref ractile bodies. During sporoblastogenesis and sporogenesis, one or two dens e polar bodies were found within the oocysts. They were composed of a dense homogeneous core, surrounded by a ring of dense granular material. On occa sion, we observed some sporocysts in direct contact with host cells. This p aper describes the morphology and ultrastructural details of the oocysts, s porocysts and sporozoites of G. clupearum. This species seems to represent the only coccidium described in fish from this Atlantic coast.