Morphological and Molecular Characterization of Potential Toxic Benthic Dinoflagellate, Gambierdiscus belizeanus (Dinophyceae) from Malaysia

Species in the genus Gambierdiscus, particularly Gambierdiscus toxicus have been known to produce a potent neurotoxin, ciguatoxin that cause ciguatera fish poisoning (CFP), the most common illness that associated with fish consumption worldwide. The dinoflagellate is commonly found in the coral reefs of ciguatera endemic area. In this study, a detailed morphological investigation by using Scanning Electron Microscopy (SEM) was conducted to characterize the Gambierdiscus species found in the Malaysian waters. A strain of Gambierdiscus sp. from Kota Kinabalu, Sabah was cultured and maintained in SWII medium at 26oC under 12:12 hr light:dark photocycle. The SEM observation of the strain showed that the cells are areolated, ellipsoid in apical view and compressed anterioposteriorly. The plate formula observed was Po, 3´, 7´´, 5´´´,1p and 2´´´´. Dimensions of the cells were 56.7 μm to 59.4 μm in depth and 57.8 μm to 64.4 μm in width. Detailed examination of important morphological features used to distinguish Gambierdiscus morphospecies such as thecal surface morphology, shape of apical pore plate (Po) and 1p plate as well as the morphometric information obtained in this study revealed similar morphological characteristics of G. belizeanus. Thus, the strain was identified as G. belizeanus. This represents the first report on the occurrence of G. belizeanus in the Pacific region