A new dinoflagellate from the Indian Ocean: a link between the genera Amphisolenia and Triposolenia (Dinophyceae)?

An interesting dinoflagellate belonging to the Order Dinophysiales was found in a phytoplankton sample collected by net from the Indian Ocean (13°35.8′N, 70°50.0′E) on the cruise IOE ‘Meteor’. The specimen was isolated and studied by light and scanning electron microscopy. The species has a large cell size (340 μm length and 55 μm width) with some characters typical of the genus Amphisolenia Stein: compressed head, short neck, and an elongated, wide midbody. However, it lacks a posterior narrowing and develops two nearly straight and symmetrical posterior processes, each with two spines at the end, which are features of the genus Triposolenia Kofoid. Therefore, we are dealing with a new species, Triposolenia fallax Hernández-Becerril et Meave, which has unique characteristics. We consider this species to be a link between the two genera of the Family Amphisoleniaceae. The adaptive morphology of the species and possible evolutionary trends of the genera are discussed.