Four new Myxobolus species are described from cyprinid fishes of the M
esopotamian Fauna Region in Iran. Each species infects a specific site
of their fish hosts. Myxobolus iranicus sp. n. forms large plasmodia
in the spleen of Barbus sharpeyi and B. luteus. The plasmodia of M. me
sopotamiae sp. n. are located in the fins of B. grypus, B. luteus and
B. rajanorum. The plasmodia of M. shadgani sp. n. develop on the carti
lageous rays of the gill filament in a. rajanorum, while M. sharpeyi s
p. n. forms plasmodia inside the cartilageous gill arches of B. sharpe
yi.