Does the pinnatoxin-producing dinoflagellate, Vulcanodinium rugosum, comprise a species complex?

Pinnatoxins are members of the toxic cyclic imine group and were first characterized over two decades ago. However, the dinoflagellate producer of pinnatoxins was not known until 2011 when cultured from sediment samples in New Zealand. The causative species, Vulcanodinium rugosum Nezan & Chomerat, was described in 2011 from a bloom sample from a Mediterranean lagoon. V. rugosum has now been recorded around the world including Australia, New Zealand, Japan, China, Hawaii and Europe. V. rugosum strains of various origins produce different pinnatoxins and also differ from each other in partial large subunit rDNA and internal transcribed spacer regions suggesting the existence of a species complex. This study sought to determine the status of this species by combining DNA sequence data, morphological characteristics, mating experiments and toxin profiles from strains originating from five geographical locations.