Four species of the genus

ABSTRACT. A new species of myxosporean of the genus Kudoa was found in the muscle tissues of Pamatoschistus minutus (Pallas, 1770), a migratory fish species from the Mediterranean Sea. Previously this Kudoa species had been observed in Pomatoschistus microps (Krøyer, 1838), a sedentary species of the Vaccarés lagoon system. the parasite caused rapid myoliquefaction of the affected muscles within one hour after host death. Using both light and electron microscopy, whitish, longitudinal, spindle‐shaped bodies, 2‐5 mm long and 1‐2 mm wide, were found in the caudal peduncle or in muscle tissues of the abdominal wall. Spore length, width, and thickness (n = 30) ranged between 4.4‐6.0 üm, 6.4‐8.0 üm, and 4.4‐6.0 üm, respectively, while the polar capsules averaged 2.5 times 1.5 üm (n = 30). Anatomic comparison with other myxosporean parasites enabled us to determine this to be a new species that we name Kudoa camarguensis n. sp.

Specimens and nests of Pomatoschistus pictus adriaticus have been caught for the ¢rst time along the French Mediterranean shore (Gulf of Lions). Six types of nests are found on sandy-gravelly bottom at 10 m depth and 25.3 to 27.5 g l 71 salinity, using in 84.7% of cases, a valve of Cardium edule (3.34weight g440.6; 5074surface mm 2 42490). Nest size, egg patch, surface area and nesting fecundity are positively correlated. Nesting fecundity varies between 669 and 4690 eggs. For a similar egg diameter, the egg height is less than that of P. minutus which spawns on the same bottom and localities. Larval length at hatching varies from 1.70 to 2.67 mm.

ABSTRACT. Ultrastructural studies on Eimeria (syn. Epieimeria) anguillae (Apicomplexa), parasite of the digestive tract of the eel, have shown that the development of this parasite takes place completely within the host cell. Merogony and gamogony are intracellular but in the epicytoplasmic position. Sporogony is also located within the epithelial cells, which agrees with assignment of this coccidian in the family Eimeriidae. However, depending on the intensity of infection and the physiopathological reaction of the host, the gamont may behave in two ways. 1) In massive infections, gamogony stages cause a genuine destruction of intestinal epithelium. Large numbers of gamonts form nodules and parts of the seriously destroyed epithelium peel off and are released into the lumen of the gut and quickly discharged into the outer environment. This discharged epithelium envelops cells containing immature oocysts that then sporulate outside the host. 2) In light infections, the host cells, which are necrotic due to the presence of a zygote, are pushed between the surrounding intact cells towards the base of the epithelium. Closely above its basal lamella, the oocyst then undergoes sporulation. These results show no taxonomically important biological features (e.g. special mode of implantation to the host cell or active movement of the zygote). Because the morphological characteristics of Epieimeria do not differ significantly from Eimeria, we propose to suppress the genus Epieimeria Dyková and Lom, 1981, and relegate its species into the genus Eimeria.

A Myxobolus heterospora (Baker, 1963) infection was found in 2 euryhaline tilapia species, Sarotherodon melanotheron melanotheron (Rüppel, 1853) and Tilapia zillii (Gervais, 1852), from a brackish water lake, Lake Nokoué (Benin, West Africa). The histology and ultrastructure of different levels of infection in intestinal connective tissues and wall tissues is described. A total of 391 S. melanotheron melanotheron and 222 T. zillii were examined from October 1987 to October 1989. M. heterospora was found throughout the study period, with a total prevalence of 42.19 and 26.57% for S. melanotheron melanotheron and T. zillii respectively. There was a statistically significant difference in occurrence as a function of season in S. melanotheron melanotheron but not in T. zillii, and there was a significant difference for size and sex in the former and for sex in the latter. M. heterospora induces total destruction of the intestine structure and probably leads to osmoregulatory disturbance. Further investigations of this myxosporean infection are necessary to determine its real effect on the host, since host survival and osmoregulatory rate have not yet been assessed.