The morphology and systematic status of Khawia rossittensis (Szidat, 1937) and K. parva (Zmeev, 1936) (Cestoda: Caryophyllidea), parasites of cyprinid fishes.

The morphology of the two little-known fish cestodes of the genus Khawia Hsü, 1935, K. rossittensis (Szidat, 1937) and K. parva (Zmeev, 1936) from cyprinid fishes, were studied on the basis of newly collected specimens from goldfish Carassius auratus auratus (L.) and museum specimens, respectively. This paper provides the first detailed species diagnosis for K. rossittensis from Slovakia, which is compared with specimens from different geographical regions and K. parva, a somewhat similar Far Eastern species from the same host. The two species differ in scolex morphology, anterior extent of the vitelline follicles, shape of the ovary and size of the eggs. Based on these differences, K. rossittensis and K. parva are considered to be separate taxa. K. parva, listed among the "species incertae sedis" by Mackiewicz (1972) and even within Caryophyllaeus Gmelin, 1790 by Schmidt (1986), should be considered a valid species of Khawia. The results support the previous conclusions of Kulakovskaya (1961), Dubinina (1971) and Protasova et al. (1990).