Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 27. (Budapest, 1994)

eastern territory of Iran, belongs to the Palaearctic. The myxosporean fauna of the latter region is well studied (Shulman 1984). At the same time, only scarce information is available on the myxosporean fauna of fishes in the Mesopotamian Fauna Region. From Iranian fishes, Ebrahimi and Kailani (1976) and Moghainemi and Abasi (in press) reported the occurrence of some Myxobolus spp. infecting the gills of fishes in River Karun. Another report came from Mokhayer (1981) who also described Myxobolus lobatus from Barbus brachycephalus. The occurrence of Myxobolus mulleri and M. oviformis in the neighbouring Iraqi freshwaters was first reported by Herzog (1969). Subsequently Al-Salim (1986) and Rashid et al. (1989) described the occurrence of Myxobolus pfeifferi in different barboid fishes. This paper describes two new Myxobolus species, M. karuni and M. persicus from the gills of Barbus grypus. MATERIALS AND METHODS The fishes involved in this study comprised 24 specimens of Barbus grypus (Heckel, 1843), 22-43 cm in length; 42 specimens of Barbus sharpeyi (Günther, 1874), 10-31 cm in length; and 14 Barbus luteus (Heckel, 1843), 12-24 cm in length. Fish were collected monthly in the period between June and November 1993 from seven different stations of River Karun in Khuzestan Province situated in Southwest Iran. Immediately after collection, the fish were transported in live condition to the laboratory where they were weighed and measured before being killed by transection of the spinal cord. They were then examined for myxosporean parasites under stereoand light microscope. Spores were obtained from mature cysts in each organ sample. On the average, 30 spores were measured using the parameters recommended by Lorn and Arthur (1989). Permanent preparations were made by placing a portion of the spores into glycerol-gelatin and mounting them on a coverslip. The structure of the polar capsules and the iodophilous vacuole was studied under Nomarski interference microscopy. For histological examination, infected organs were fixed in 10% buffered formalin, then embedded in paraffin wax, cut in 5 ^m thick sections, and stained with haematoxylin and eosin. RESULTS Eighteen specimens of & grypus (75%) were infected by Myxobolus cysts on the gills. Two types of cysts were differentiated. Some of the cysts were located in the tissues of the primary filaments forming plasmodia in the blood vessels, others were developing in the secondary lamellae, so that the cysts grew around the capillary of the lamellae. Spores obtained from the two types of cysts differed in both shape and size (Fig 1). Of the two other barboid fish species 7 specimens of B. sharpeyi (16%) and 2 specimens of B. luteus (14%) were infected by Myxobolus cysts. In these fishes all cysts developed in the secondary lamellae.