Of the five species of Lepeophtheirus so far recorded from the ocean sunfish (Mola mola), L. ornatus Edwards has been previously synonymized with L. nordmanni Edwards. A comparison of specimens shows that L. insignis Wilson is also a synonym of L. nordmanni and that L. molae Heegaard is a synonym of L. hastatus Shiino. Lepeophtheirus nordmanni and L. hastatus are redescribed and compared. Lepeophtheirus hastatus can be distinguished from L. nordmanni by an accessory branch on its postantennary spine; in the female L. hastatus, the fifth legs are styliform whereas in female L. nordmanni they are lamelliform; the male of the latter species has a reduced sternal furca whereas male L. hastatus have a sternal furca extending beyond the interpodal bar.The great similarity between the two species casts doubts on most previous records of Lepeophtheirus from M. mola and the known distribution of these parasites is discussed.Since the fifth legs of L. hastatus are very similar to those found in Dentigryps Wilson, and these legs are the only distinguishing feature of this genus, the species previously placed in Dentigryps are transferred to Lepeophtheirus. The following new combinations are proposed: Lepeophtheirus curtus (Wilson, 1913) n. comb., L. litus (Lewis, 1964) n. comb., L. ulua (Lewis, 1964) n.comb., and L. longicauda (Cressey, 1966) n.comb. Lepeophtheirus lewisi nom.nov. is proposed for D. bifurcatus Lewis, 1964.