Species of the marine benthic dinoflagellate genus Gambierdiscus Adachi & Fukuyo are morphologically similar, and DNA based sequence analyses are necessary to complement morphological species determination. Gambierdiscus species may produce ciguatoxins, the causative agents of human illness ciguatera poisoning (CP). In this study, morphological descriptions, based on laboratory cultures, using light and scanning electron microscopy and DNA based characterisation of one strain (ISOG4) isolated from Petite Rivière Noire, Mauritius are provided. Our morphological observations coupled with DNA based sequence analyses indicate that the Mauritian strain is Gambierdiscus caribaeus Vandersea, Litaker, M.A.Faust, Kibler, W.C.Holland & P.A.Tester. Our strain bears close similarity (LSU 99% identity) to Gambierdiscus caribaeus (GenBank[KY448444]) isolated from Canary Islands, Spain, and phylogenetic results depict it as sister to G. jejuensis S.H.Jang & H.J.Jeong. Gambierdiscus caribaeus (ISOG4) is herein a first report from Mauritius Island and the Mascarene region.