• Chattonella verruculosa;
  • Dictyochophyceae;
  • flagellar apparatus;
  • harmful algal bloom;
  • phylogenetic analysis;
  • Pseudochattonella verruculosa;
  • Raphidophyceae


Chattonella verruculosa Y. Hara et Chihara was re-examined by molecular methods and microscopic examination. The 18S rDNA phylogenetic analysis clearly indicated that C. verruculosa is a member of the Dictyochophyceae, with a specific affinity to Florenciella parvula. The morphological features in C. verruculosa– namely the proximal helix with two gyres and many scattered DNA-containing areas in the chloroplasts – display the evolutionary link to the Dictyochophyceae, instead of the Raphidophyceae. Similarly, unique pyrenoid morphologies are shared between C. verruculosa and the dictyochophycean algae. Combining the molecular data and morphological characteristics, C. verruculosa is transferred to Pseudochattonella gen. nov. of the class Dictyochophyceae as Pseudochattonella verruculosa (Y. Hara et Chihara) Hosoi-Tanabe, Honda, Fukaya, Inagaki et Sako comb. nov.