Harpacticus Milne Edwards, 1840 (Crustacea, Copepoda, Harpacticoida) from three Islands of Western Antarctica with description of a new species

The study of Antarctic harpacticoid copepods is essential for understanding the biodiversity of extreme environments yet remains unexplored. This research, conducted during the sixth Turkish Antarctic Expedition, addresses the knowledge gap by investigating the harpacticoid fauna from three islands in western Antarctica: Dismal, Horseshoe, and Nansen. Samples from various aquatic habitats were meticulously analysed, leading to the identification of Harpacticus furcatus and the discovery of a new species, Harpacticus tae n. sp. The new species is characterized by unique morphological features, such as the absence of the abexopodal seta on the male antenna, distinguishing it from related species. On the other hand, our detailed re-description of H. furcatus allowed us to review and discuss previous literature in the context of our findings, offering a comprehensive update on its taxonomy and ecological significance. This review also highlights the circum-Antarctic distribution and broad salinity tolerance of H. furcatus. The study utilized advanced imaging techniques, including Differential Interference Contrast microscopy and Scanning Electron Microscopy, to provide detailed descriptions of the species. These findings not only contribute to the taxonomy and biodiversity knowledge of Antarctic harpacticoids but also underscore the importance of further research on meiofaunal diversity in polar regions, highlighting its potential significance in understanding global biodiversity patterns.