Dinophysis diegensis Kofoid is a life history stage of Dinophysis caudata Kent (Dinophyceae, Dinophysiales)

Abstract

Several species of Dinophysis Ehrenb. have been observed to produce “small cells” that are different in size and shape from the vegetative cells, following a reductionary division under certain environmental conditions, as part of a polymorphic life cycle. Based on observations on fixed field samples, D. diegensis Kof. was hypothesized to be a small form of D. caudata Saville-Kent. In this study, this hypothesis was confirmed after incubations, in cell culture chambers, of groups of individually picked vegetative cells from natural populations of D. caudata. Eight to 10 d after inoculation, different life-cycle stages were observed in the wells. Illustrations of small and intermediate forms of D. caudata developed in vitro were contrasted with those observed during their proliferation in the northeast Atlantic (Galicia) and northwest Mediterranean (Catalonia) coasts of Iberia. It is proposed that Dinophysis diegensis–like specimens should be considered as a taxonomic (or heterotypic) synonym of Dinophysis caudata. A historical overview is provided (see Supplementary material) that revises the large list of taxa used to nominate different morphotypes of D. caudata, and its small and intermediate cells, since its original description by Saville-Kent in 1881.