Taxonomy of Gambierdiscus including four new species, Gambierdiscus caribaeus, Gambierdiscus carolinianus, Gambierdiscus carpenteri and Gambierdiscus ruetzleri (Gonyaulacales, Dinophyceae)

Abstract

Gambierdiscus species produce toxins that cause ciguatera fish poisoning (CFP), the most common nonbacterial illness associated with fish consumption worldwide. Understanding the role that individual Gambierdiscus species play in causing CFP is hampered because the morphologically similar species in the genus are difficult to distinguish. Ambiguities in the description of the type species Gambierdiscus toxicus also exist. This paper presents detailed line drawings along with additional scanning electron microscopy (SEM) and light micrographs to more fully characterize the six known Gambierdiscus species in addition to describing four new species, Gambierdiscus caribaeus sp. nov Gambierdiscus carolinianus sp. nov., Gambierdiscus carpenteri sp. nov., and Gambierdiscus ruetzleri sp. nov. All four of the' new species are photosynthetic and epibenthic and have a Kofoidian plate formula of Po, 3', 7", 6C, 6 or 7S, 5'", Ip, and 2"". Establishment of these species is supported by both morphological differences and three independent phyloge'netic analyses utilizing small-subunit, as well as D1-D3 and D8-D10 large-subunit rDNA gene sequences. During the course of this study it became apparent that the description of the type species, G toxicus, included more than one species. Since no type material exists we propose that Fig. 1 in Adachi and Fukuyo (1979) be designated as the lectotype for this species and that the epithecal view of isolate GTT-91 shown in Fig. 1 from Chinain et al. (1999) be designated as the epitype. The GTT-91 isolate has been well characterized genetically and the original SEM stub of this isolate archived at the Smithsonian Institution has been re-examined to provide a more detailed morphological analysis of the epitype.