Morphology, molecular phylogeny and toxicity of Fukuyoa paulensis (Dinophyceae) from the Bay of Bengal, North Indian Ocean

Fukuyoa species are potential producers of polyether neurotoxins that are toxic to aquatic biota and humans. A strain of Fukuyoa (CSIRCSMCRI 004) was isolated from India’s Bay of Bengal coast. The clonal culture was identified using light and scanning electron microscopy and molecular phylogenetic analysis of the LSU rRNA gene and ITS (ITS1-5.8S gene-ITS2) sequences. Its toxicity was assessed using a 48 h Artemia bioassay. The morphological features observed included globular shape, descending cingular displacement, broad pentagonal 1′ plate, and large second apical plate (2′). The identity of the strain was confirmed to be F. paulensis based on the LSU rRNA gene and ITS sequences phylogenies. Strain CSIRCSMCRI 004 shared an identical sequence with the type strain of F. paulensis and other strains reported from different locations, based on the LSU rRNA gene and ITS sequences phylogenies. Exposure of brine shrimp larvae to its cellular lysate resulted in lethality (48 h LC50 = 0.256 mg ml−1) and behavioral abnormalities. The current study provides the first evidence of F. paulensis in the Bay of Bengal. It also reveals that CSIRCSMCRI 004 is toxic to susceptible biota like the brine shrimp and could produce ciguatera-associated toxins. The findings of this study highlight the need for sampling and screening of ciguatera-related species in the Bay of Bengal region to understand the associated public and environmental health risks.