Resolving taxonomic and nomenclatural problems in the genus Caligus O. F. Müller, 1785 (Copepoda: Caligidae) Author Boxshall, Geoffrey A. Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW 7 5 BD, UK Author Bernot, James P. Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC, 20560, USA Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA text Zootaxa 2023 2023-10-30 5360 4 545 567 https://www.mapress.com/zt/article/download/zootaxa.5360.4.5/52133 journal article 10.11646/zootaxa.5360.4.5 1175-5326 10084656 EA1BE6F9-88E2-4357-895E-8ED415206592 Caligus raniceps Heegaard, 1943 and Caligus curtus Müller, 1785 The description of Caligus raniceps was based on three male specimens stored in the collections of the Swedish Museum of Natural History ( Heegaard, 1943 ). Heegaard’s paper states that these males were collected in the “ Bay of Bengal” by Captain Sundevalle and “host unknown” but it does not specify whether the specimens were taken from the plankton or from an unidentified fish. The description lacks detail but in the features that are mentioned or illustrated, C. raniceps appears identical to the male of C. curtus as redescribed by Parker et al. (1968) , as already commented by Pillai (1985) . The maxilliped of the male bears distinctive myxal processes opposing the tip of the subchela, one proximal to and one distal to the tip of the subchela when adducted. This configuration is the same in both species. In addition, leg 4 is 3-segmented and bears 3 distal margin spines, the innermost of which is more than twice as long as the other 2 spines and longer than the segment, the sternal furca has short divergent tines, and the body length (given as 9 to 12 mm ) is unusually large. With our current state of knowledge, the syntype males of C. raniceps are identifiable as C. curtus and we consider that Caligus raniceps Heegaard, 1943 should be treated as a junior subjective synonym of Caligus curtus Müller, 1785 . Caligus curtus is widely distributed in the northern Atlantic region ( Parker et al. , 1968 ; Dojiri & Ho, 2013 ) but has never been reported from the Pacific or Indian Oceans except for Heegaard’s (1943) paper. We consider it extremely unlikely that this cold-water Atlantic species occurs in Indian waters. Heegaard’s (1943) paper was based on material collected from numerous localities around the world and stored in the Riksmuseum, Stockholm , and we agree with Pillai (1985) who commented “probably there has been some confusion in the labels regarding the collection locality”.