The genus Vatacarus Southcott is revised to include the following subgenera: Vatacarus sens. str., infesting the tracheal sacs of amphibious sea snakes of the genus Laticauda; Babiangia Southcott 1957, infesting the skin of lizards; and Iguanacarus n. subg., infesting the nasal fossae of marine iguanas on the Galapagos Islands. The genus Vatacarus is clearly derived from the same stem as Eutrombicula Ewing. 2. A new subgenus, Iguanacarus, is described with two new species: V. (I.) amblyrhynchus (type species) and V. (I.) intranasalis, both from nasal fossae of marine iguanas, Amblyrhynchus cristatus (Bell.) from the Galapagos Islands (Ecuador). All five specimens of Amblyrhynchus cristatus autopsied were found heavily infested by an equal number of both species.