Morphological and molecular characterization of Kareniaceae (Dinophyceae, Gymnodiniales) in Kuwait’s waters

Abstract Kuwait’s waters were first faced with a bloom of ichthyotoxic dinoflagellate Karenia and fish kill in 1999. Since then, there have been sporadic blooms and records of various kareniacean taxa, but accurate species identification has been challenging due to the high morphological similarity among morphotypes and the lack of molecular studies. Ten clonal kareniacean strains isolated from Kuwait’s coastal waters were characterized based on light and fluorescence microscopy and the LSU rDNA gene sequencing. Seven strains represented the distinctive morphology of Karenia papilionacea and showed LSU rDNA sequences with > 99 % similarity to the type material of this species. One Karenia strain represented the typical morphology of Karenia selliformis and the LSU rDNA sequence fell within a well-supported K. selliformis clade. Two other strains showed the typical morphology of Karlodinium ballantinum and phylogenetic analysis supported the morphological results. Consequently, a combination of morphological and molecular analyses confirmed the presence of K. papilionacea and K. selliformis in Kuwait’s waters, thereby resolving the previous regional taxonomic uncertainty regarding these species. The identification of K. ballantinum represents the first regional record. Investigating the morphology and phylogeny of commonly occurring Kareniaceae enhances the monitoring and risk assessment of harmful algal blooms in Kuwait’s marine environment.