Two new species of Isodrusus Sharp are described herein: I. howdenae Cortés-Hernández and Anderson, new species, from Oaxaca, Mexico; and I. curacaoensis Cortés-Hernández and Anderson, new species, from Christoffel National Park, Curaçao, which represents the southernmost occurrence of any described species of the genus. Isodrusus howdenae can be separated from other Isodrusus by the presence of a tooth on the lateral prothoracic margin where the vibrissae are set, the sinuate inner edge of the mesotibiae with two or three small teeth, the lack of a median sulcus on the rostrum, and a small fovea present between the eyes. Isodrusus curacaoensis is distinct in having legs with only one tarsal claw, elytra in lateral view almost evenly arcuate without an abrupt apical declivity, no postocular vibrissae, the antennal scrobe visible in dorsal view, the bowed scape bowed, scales with ecarinate margins, and the anterior margin of the epistome emarginate. A revised key to the species of Isodrusus is provided.