Microncocotyle bicoccae n. sp. (Monogenoidea; Dactylogyridae) is described from the gill filaments of the longtail silverbiddy, Gerres longirostris (Teleostei: Gerreidae), collected from Ras Mohammed National Park near Sharm El-Sheikh, Egypt. The monotypic Microncocotyle gen. n. is proposed for this species and is characterized, in part, by its members possessing a cup-shaped haptor armed with a ventral anchor/bar complex (dorsal complex absent); 14 hooks with pairs 2–4, 6 and 7 marginal and pairs 1 and 5 central in the haptor; one pair of eyespots; confluent intestinal ceca lacking diverticula; tandem gonads; a vas deferens looping the left intestinal cecum; articulated male copulatory organ and accessory piece; and a dextromarginal vaginal pore. Maximum parsimony and Bayesian interference analyses of the 18S rDNA gene suggest that Microncocotyle originated independently of two other dactylogyrid genera, Dactylogyrus and Pseudodactylogyrus, in which species possess a single anchor/bar complex.