Exploration of Overlooked Aduncodinium-Like (Pfiesteriaceae, Dinophyceae) Diversity.

The dinoflagellate genus Aduncodinium was erected to encompass Katodinium glandula, belonging to the family Pfiesteriaceae. Other described species, like K. asymmetricum, show Aduncodinium-like characters and probably belong to this genus. These two species are commonly reported in the literature. However, detailed morphological characterization of observed specimens is rarely provided mostly due to difficulties in culturing and studying these thin-walled dinoflagellates. Likewise, molecular information for Aduncodinium-like species is scarce. In this study, we provide a morpho-molecular characterization of Aduncodinium-like morphospecies mostly detected in coastal sediments from Spain, Germany, Japan, and Canada. The information collected and the detections reported in the literature, mostly referring to K. glandula or K. asymmetricum, highlight the existence of a largely overlooked diversity of Aduncodinium-like taxa, and the existence of cryptic diversity in some morphospecies. In fact, up to 16 different morphospecies are reported in this study, some of them supported by their molecular information, which can be assigned to different morphogroups. The information collected results in the description of the new species Aduncodinium robustum sp. nov.