Gambierdiscus larsenii sp. nov. Nguyen-Ngoc & Doan-Nhu – New toxic microalgal species capable of causing ciguatera poisoning identified in Vietnamese waters

18/08/2026

As part of an international collaborative research project (code QTRU06.05/24-26), Prof. Dr Doan Nhu Hai and colleagues at the Institute of Oceanography under the Vietnam Academy of Science and Technology (VAST) have announced the discovery of a new microalgal species in the genus Gambierdiscus that is capable of producing toxins associated with ciguatera poisoning in the central waters of Vietnam.

Cell morphology and composition of thecal plates of Gambierdiscus larsenii sp. nov. Nguyen-Ngoc & Doan-Nhu under scanning electron microscopy (SEM)

In the study recently published in the journal Harmful Algae (https://doi.org/10.1016/j.hal.2026.103174), the authors described Gambierdiscus larsenii sp. nov., a new species isolated from the central waters of Vietnam. The findings showed that the species shares many morphological characteristics with closely related species such as G. caribaeus, G. carpenteri, G. jejuensis and G. toxicus. No single morphological characteristic is sufficient to clearly distinguish G. larsenii from these species. The research team therefore applied an integrative taxonomy approach, combining morphological characteristics (Figure 1) with molecular data (Figure 2), to establish and describe the new species.

Phylogenetic tree based on LSU rDNA (D1–D3) sequences of Gambierdiscus species. Values at the nodes represent PP and BS (1,000 bootstrap); only PP ≥ 0.70 and BS ≥ 50 are shown. Sequences of G. larsenii sp. nov. are shown in bold. Rectangles indicate species groups supported by four species delimitation methods: ABGD, bPTP, mlPTP and ASAP

The discovery and description of Gambierdiscus larsenii sp. nov. not only contributes to a better understanding of the biodiversity of the genus Gambierdiscus in the Western Pacific, but also provides an important scientific basis for monitoring toxin-producing microalgal species, assessing the risk of ciguatera poisoning, and supporting food safety management and coral reef ecosystem conservation amid climate change in Vietnam.

Translated by Phuong Huyen
Link to Vietnamese version