The largely neglected Lesser Antillean scorpion Tityus atriventer Pocock, 1897 is herein redescribed, after study of the two syntypes and one additional adult male. The latter was recently collected from Union Island (about 55 km northeast of Grenada), and it implies the first published finding of this species after its original description, and the first record of the species both outside the type-locality and from the Grenadines islands. The taxonomic position of T. atriventer is clarified (including designation of a lectotype and a paralectotype), its diagnosis is updated, a fully illustrated redescription is presented according to the current taxonomy of the genus, and a comparison to its morphologically closest relatives is also provided.