A revision of the Atlantic and Pacific species of Ligophorus Euzet et Suriano, 1977 based on abundant newly sampled material from mugilids of the Mediterranean Sea, Sea of Japan and South China Sea, as well as available type and voucher specimens, is presented. All 35 nominal species of Ligophorus known from the Atlantic and the Pacific waters are treated. Of them, 30 are considered valid, one incertae sedis (L. leporinus), one species inquirendae (L. chongmingensis), two junior synonyms (L. euzeti and L. gussevi) and one is transferred to another genus. Three new species of Ligophorus are described: L. triangularis, L. miroshnichenki, and L. rectus. An amended diagnosis of Ligophorus is given with critical comments on previous definition of key features of the genus. Description of the main morphological types for the copulatory organ, the accessory piece of the copulatory complex, the distal end of the vagina, the ventral bar and anchors are provided. The taxonomic importance of sclerotized parts is discussed in relation with their functional morphology. For each species, previous and present records on host and geographic distribution were compiled. A new genus of Dactylogyridae Kriboetrema is proposed for species morphologically similar to Ligophorus spp., but which differ from the latter in having a large dorsoventrally flattened body, a coiled copulatory organ with a bulbous base, two prostatic reservoirs, a subovate or piryform ovary and inconspicuous or poorly developed lateral flaps of the haptor. Two species are proposed for allocation within the new genus, K. ellochelon comb. n. and K. rectangulus sp. n., from Liza vaigiensis and Valamugil cunnesius, respectively, in the Pacific. A key to genera and valid species in the surveyed regions is provided.