Phylogeny, morphology and toxicity of benthic dinoflagellates of the genus Fukuyoa (Goniodomataceae, Dinophyceae) from a subtropical reef ecosystem in the South China Sea

• Published in: Harmful algae 2018-04, Vol.74, p.78-97
• Main Authors: Leung, Priscilla T.Y., Yan, Meng, Lam, Veronica T.T., Yiu, Sam K.F., Chen, Chia-Yun, Murray, J. Sam, Harwood, D. Tim, Rhodes, Lesley L., Lam, Paul K.S., Wai, Tak-Cheung
• Format: Article
• Language: English
• Subjects: Animals; Artemia - drug effects; Chromatography, Liquid; Ciguatera; Coral and rocky reefs; Coral Reefs; CTX and MTX; Dinoflagellida - chemistry; Dinoflagellida - classification; Dinoflagellida - cytology; Dinoflagellida - ultrastructure; DNA, Algal - analysis; Gambierdiscus; Hong Kong; Microscopy, Electron, Scanning; Oceans and Seas; Phylogeny; RNA, Ribosomal, 18S - analysis; RNA, Ribosomal, 28S - analysis; Tandem Mass Spectrometry; Toxic epiphytic algae; Toxicity Tests, Acute
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2018.03.003

•Benthic dinoflagellates Fukuyoa spp. were first time identified from South China Sea, coexisting with Coolia spp., Ostreopsis sp., Prorocentrum spp. and Amphidinium spp. in Hong Kong.•Phylogenetic and morphological analyses revealed a putative new species namely Fukuyoa sp. HK type I.•Multivariate analysis of epithecal plate parameters characterized the species of Fukuyoa.•Bioassay revealed that F. ruetzleri and Fukuyoa sp. HK Type I were toxic to biota.•All isolates of Fukuyoa produced neither P-CTXs nor MTX-1, but isolates of F. ruetzleri produced a putative MTX-3. Species of Fukuyoa, recently revised from the globular Gambierdiscus, are toxic benthic dinoflagellates associated with ciguatera. In this study, a total of ten strains of Fukuyoa collected from Hong Kong waters were characterized using morphological and phylogenetic analyses. Results from both analyses showed that one of the strains is a putative new species, namely Fukuyoa sp. HK Type 1 (plate formula Po, 3′, 7″, 6c, 7s, 5‴, 1p and 2′‴ with a distinctive small and narrow cell shape, narrow Po plate, high Po pore density, large and broad Plate 1′ but small and round Po pore size, small and narrow Plate 2′, long and narrow Plates 2′‴ and 1p), and the others were F. ruetzleri. This is the first report of these two species of Fukuyoa in the South China Sea and Asia-Pacific region. Phylogenies on 18S, 28S D1/D3 and D8/D10 ribosomal DNA sequences strongly support that Fukuyoa sp. HK Type 1 is currently the most divergent species in the genus Fukuyoa. The diagrammatic plots on the p-distance matrices of 18S, 28S D1/D3 and D8/D10 and ITS regions resolved that the species of Fukuyoa were separated into three main groups, i.e., Fukuyoa sp. HK Type 1, F. paulensis and a group consisting of F. ruetzleri, F. yasumotoi and F. cf. yasumotoi, while Fukuyoa sp. HK Type 1 was always the most distant from the other two groups. Additionally, the pairwise p-distance values calculated based on the ITS region have always been the highest for pairs between Fukuyoa sp. HK Type 1 and other Fukuyoa species, ranging from 0.142 to 0.150. Our molecular results suggested that Fukuyoa sp. HK Type 1 is a putative new species. Both morphological and molecular data of more strains from different localities should be, however, collected to address its intraspecific variability and further evaluate its taxonomic status. A bioassay analysis demonstrated that algal lysates extracted from F. ruetzleri and Fukuyoa sp. HK Type 1 we