Heterocapsa busanensis sp. nov. (Peridiniales, Dinophyceae): A new marine thecate dinoflagellate from Korean coastal waters

During daily monitoring in Yongho Bay off Busan, Korea in 2019, an isolate of the dinoflagellate genus Heterocapsa was established in clonal culture. Light and electron microscopic examination revealed that the isolate was ellipsoid in shape, exhibiting a thecal plate arrangement (Po, cp, X, 5', 3a, 7 '', 6c, 5s, 5''', 2'''') consistent with most other Heterocapsa species. A large, elongated nucleus was positioned on the left side of the cell, a single reticulate chloroplast was located peripherally, and a single, starch-sheathed, spherical pyrenoid was present in the episome or near the cingulum. Morphologically, the isolate most closely resembles H. circularisquama and H. illdefina. Transmission electron microscopic examination of whole mounts revealed that the isolate had two body scale types, one of which was a complex, three-dimensional, fine structure distinct from other Heterocapsa species, whereas the other simpler type was structurally similar to the scales of H. horiguchii. Molecular phylogeny based on rRNA sequences revealed that the isolate was distantly related to morphologically similar species, but formed a sister lineage to H. horiguchii, a species characterized by a similar body scale morphology. Based on morphological, ultrastructural, and molecular data, we proposed it as a new species, Heterocapsa busanensis sp. nov. (C) 2021 Elsevier GmbH. All rights reserved.

Automated summary

During monitoring in Yongho Bay off Busan, Korea in 2019, a new species of the dinoflagellate genus Heterocapsa, named Heterocapsa busanensis, was identified. This species displayed unique characteristics in cell morphology, body scale structure, and molecular phylogeny compared to other known Heterocapsa species.