The taxonomy of the rare Macrophthalmus leptophthalmus (H. Milne Edwards, 1852) is reviewed. On the basis of distinctive features of the carapace, eyes, and epistome, M. leptophthalmus is assigned to the subgenus, Euplax H. Milne Edwards, 1852, new status, a taxon that has been incorrectly synonymised under Macrophthalmus (Venitus) Barnes, 1967. A related species, Macrophthalmus (Euplax) dagohoyi, new species, is described from subtidal mangroves in Bohol, central Philippines. Macrophthalmus (Euplax) dagohoyi can easily be distinguished from M. (Euplax) leptophthalmus by different carapace, cheliped, walking leg and sternal characters. A key to the genera and subgenera of Macrophthalmidae is also presented.