The West Indian genus Diastolinus Mulsant and Rey, 1859 (type species: Blaps clathratus Fabricius) is revised. The genus now includes 18 species divided among three species-groups, eight of which are described as new species herein: Diastolinus chalumeaui Hart and Ivie, new species (Guadeloupe Archipelago); Diastolinus leewardensis Hart and Ivie, new species (Leeward Islands); Diastolinus shieli Hart and Ivie, new species (Redonda); Diastolinus azuaensis Hart and Ivie, new species (Hispaniola); Diastolinus desecheo Hart and Ivie, new species (Desecheo Island); Diastolinus doyeni Hart and Ivie, new species (Puerto Rico); Diastolinus vaderi Hart and Ivie, new species (Hispaniola); and Diastolinus hoppae Hart and Ivie, new species (St. Lucia). The following new synonymies are proposed: Diastolinus hummelincki Marcuzzi, 1962 = Diastolinus clavatus Mulsant and Rey, 1859, new synonymy; Diastolinus mulsanti Marcuzzi and D'Aguilar, 1971 = Diastolinus clavatus Mulsant and Rey, 1859, new synonymy; and Diastolinus estebani Garrido, 2004 = Diastolinus coarctatus (Mulsant and Rey, 1859), new synonymy. A lectotype and paralectotypes are designated for Diastolinus hummelincki Marcuzzi, 1962 (not Marcuzzi, 1949 nor 1950), Blaps clathrata Fabricius, 1792, Ctesicles insularis Champion, 1896, and Ctesicles maritimus Champion, 1896. All species are keyed, illustrated, and redescribed, and extensive corrections of misidentifications are reviewed. All 18 species are readily distinguished by both morphological and biogeographical attributes. Newly revised distributions demonstrate that most species distributions can be closely tied to Pleistocene eustastic minima