Recent molecular phylogenetic studies of Gambierdiscus species flagged several new species and genotypes, thus leading to revitalizing its systematics. The inter-relationships of clades revealed by the primary sequence information of nuclear ribosomal genes (rDNA), however, can sometimes be equivocal, and therefore, in this study, the taxonomic status of a ribotype, Gambierdiscus sp. type 6, was evaluated using specimens collected from the original locality, Marakei Island, Republic of Kiribati; and specimens found in Rawa Island, Peninsular Malaysia, were further used for comparison. Morphologically, the ribotype cells resembled G. scabrosus, G. belizeanus, G. balechii, G. cheloniae and G. lapillus in thecal ornamentation, where the thecal surfaces are reticulate-foveated, but differed from G. scabrosus by its hatchet-shaped Plate 2′, and G. belizeanus by the asymmetrical Plate 3′. To identify the phylogenetic relationship of this ribotype, a large dataset of the large subunit (LSU) and small subunit (SSU) rDNAs were compiled, and performed comprehensive analyses, using Bayesian-inference, maximum-parsimony, and maximum-likelihood, for the latter two incorporating the sequence-structure information of the SSU rDNA. Both the LSU and SSU rDNA phylogenetic trees displayed an identical topology and supported the hypothesis that the relationship between Gambierdiscus sp. type 6 and G. balechii was monophyletic. As a result, the taxonomic status of Gambierdiscus sp. type 6 was revised, and assigned as Gambierdiscus balechii. Toxicity analysis using neuroblastoma N2A assay confirmed that the Central Pacific strains were toxic, ranging from 1.1 to 19.9 fg P-CTX-1 eq cell⁻¹, but no toxicity was detected in a Western Pacific strain. This suggested that the species might be one of the species contributing to the high incidence rate of ciguatera fish poisoning in Marakei Island.

最近的冈比亚种的分子系统发育研究标志着几种新的种和基因型，从而使它的系统学焕发了生命。然而，核核糖体基因（rDNA）的一级序列信息揭示的进化枝之间的相互关系有时可能是模棱两可的，因此，在本研究中，核糖体类型Gambierdiscus sp。的分类学地位。使用从基里巴斯共和国马拉基岛（Marakei Island）采集的标本对6型进行了评估；以及在马来西亚半岛拉瓦岛发现的标本被进一步用于比较。从形态上讲，核糖型细胞类似于G. scabrosus，G。belizeanus，ģ。ech鱼，G。cheloniae和G ^。峨螺在卵泡膜纹饰，其中鞘内表面是网纹-视网膜中央凹，但是从不同G. scabrosus由其斧形板2'，和G ^。伯利兹人通过非对称板3'。为了确定这种核型的系统发育关系，对大亚基（LSU）和小亚基（SSU）rDNA的大型数据集进行了编译，并使用贝叶斯推断，最大简约性和最大似然性进行了综合分析。后两个结合了SSU rDNA的序列结构信息。LSU和SSU rDNA系统发育树均显示相同的拓扑结构，并支持Gambierdiscus sp。之间的关系的假说。类型6和G ^。ech鱼是单系的。结果，Gambierdiscus sp。的分类学地位。修改了类型6，并指定为Gambierdiscus balechii。使用成神经细胞瘤N2A分析进行的毒性分析证实，Central Pacific菌株的毒性为1.1至19.9 fg P-CTX-1 eq细胞^-1，但在Western Pacific菌株中未检测到毒性。这表明该物种可能是导致马拉基岛中雪鱼中毒发生率较高的物种之一。