Dinoflagellates play a key ecological role in marine environments, contributing significantly to primary production and, in some cases, causing harmful algal blooms (HABs). They exhibit diverse morphologies and ecological strategies to colonize a wide range of habitats. Research has predominantly focused on HAB-forming species due to their associated health risks, potentially underrepresenting benthic diversity. In this study, we bring the first report of the unarmored benthic dinoflagellate Bispinodinium angelaceum from a sandy-bottom tide pool in Tenerife, Canary Islands. Morphological identification was based on the observation of live cells using light microscopy (LM) to identify diagnostic features such as dorsoventral cell flattening, a centrally located epicone with a circular apical groove, symmetrical cingulum, brownish-yellow lobular chloroplasts, and a U-shaped spinoid apparatus connecting two lateral pyrenoids. B. angelaceum specimens from Tenerife were slightly larger when compared to previous descriptions but exhibited consistent proportions and structural organization which likely reflected methodological rather than taxonomical differences. This new record extends the known geographic range of the species and provides valuable baseline data for future ecological and taxonomic studies of benthic dinoflagellates, emphasizing the need to better explore and document the hidden diversity of non-HAB taxa.

The occurrence of the dinoflagellates belonging to the ciguatera-related genus Gambierdiscus is reported for the first time from the north-western Arabian Gulf and northern Red Sea in the Indian Ocean basin. Gambierdiscus yasumotoi was recorded from two sampling sites on the southern Kuwait coast, and co-occurrence of G. cf. belizeanus and G. yasumotoi was found also in the Gulf of Aqaba in Jordan. The morphology of cells is described on the basis of light microscopy and scanning electron microscopy examination.