Gambierdiscus carpenteri (Dinophyceae) from Bahía de La Paz, Gulf of California: morphology, genetic affinities, and mouse toxicity

Abstract

Gambierdiscus is a marine benthic dinoflagellate genus that currently contains 19 species; some of them are toxigenic, producing ciguatoxins, maitotoxins, and other toxic compounds. The objective of this study was to document the morphological and molecular identification (ITS, 5.8S and 28S of the rDNA) of two strains of Gambierdiscus from La Gaviota Island, Gulf of California, Mexico, and a toxicity test. The shape of the 2′ plate varied between hatchet-shaped and rectangular, that complicated the differentiation between G. carpenteri and G. toxicus. Molecular markers of the three rDNA regions allowed confirmation of the taxonomic identity of G. carpenteri, separating this species from other congeners with high phylogenetic affinity, such as G. excentricus, G. toxicus and G. caribaeus. Studies of the morphological taxonomy of G. carpenteri are scarce; therefore, due to the similarity between species, the combination of morphological and molecular tools is recommended for the identification of species, such as G. carpenteri, G. excentricus, G. toxicus and G. caribaeus. The mouse bioassay showed that the examined isolate was toxic, and it is a potential etiology of ciguatera fish poisoning cases in the region. This study provides the first reliable report and ribosomal sequences of G. carpenteri for the Gulf of California, as well as data on mouse bioassay toxicity.