[In progress citation].

During a study of the gill parasites (Monogenea) of two species of Diplodus Rafinesque (Sparidae), D. sargus (Linnaeus) and D. vulgaris (Geoffroy Saint-Hilaire) from off the Algerian coast, several species of the family Diplectanidae Bychowsky, 1957 and genus Lamellodiscus Johnston & Tiegs, 1922 were collected. We present a redescription of L. ergensi Euzet & Oliver, 1966 and describe two new species, L. kechemirae n. sp. and L. tomentosus n. sp. These new species are close to L. ergensi but differ in the morphology and size of both the haptoral sclerites and the male genital system. On the basis of the dorsal lateral bars of the haptor, we suggest the recognition within the group 'ignoratus' of Oliver (1987) of two subgroups, 'ignoratus' (sensu stricto), with simple dorsal bars, and 'ergensi', with complex bars which are more or less divided in two parts. We also present a redescription of L. baeri Oliver, 1974, collected from the sparid Pagrus pagrus (Linnaeus) (the type-host) and allocate it to the 'ergensi' subgroup. All of these species of Lamellodiscus are reported from sparids off the Algerian coasts for the first time.