Machimosaurus is a large teleosaurid thalattosuchian, a marine crocodylomorph historically recovered from Upper Jurassic strata of Europe. Several fragmentary remains are assignable to this genus but only four complete skulls have been reported, two of which are currently unavailable for study. A recent revision of the material assigned to Machimosaurus recognizes four valid species in this genus. Following a critical review of the diagnostic features of the various species, we confirm that the genus Machimosaurus is monospecific with Machimosaurus hugii as the sole and unique representative.