Nine new species of Acanthomolgus are described, associated with octocorals from the Netherlands’ Antilles. In addition, notes on three species known already are provided. The species of the genus are subdivided into two groups, the mononyx-group which is exclusively West Indian, and the dionyx-gtoup which is predominantly, but not exclusively, Indo-West Pacific. A key to the West Indian species is presented. Host specificity is strongly pronounced in these associates.