Gymnodinium catenatum has been responsible for the main paralytic shellfish poisoning (PSP) events reported along the Iberian coast, where much research effort has been put into understanding its bloom dynamics. Identification of a benthic resting stage in its life cycle raised questions regarding the implications of this life stage Cur bloom dynamics. When first described, the microreticulate cyst of G. catenatum was considered unique, but recently, two additional naked dinoflagellate species with different-sized microreticulate cyst, have been described. viz. G. nolleri and G. microreticulatum. Here, we report on the size distribution of microreticulate cysts from recent sediments along the Portuguese coast and describe the Occurrence of G. microreticulatum in European coastal waters. We also present field data on the distribution of G. catenatum cysts, which support the growing evidence for a planktonic origin for G. catenatum blooms in Iberian waters rather than in benthic cyst beds.