Caligus curtus Müller, 1785

Boxshall, Geoffrey A. & Bernot, James P., 2023, Resolving taxonomic and nomenclatural problems in the genus Caligus O. F. Müller, 1785 (Copepoda: Caligidae), Zootaxa 5360 (4), pp. 545-567 : 556

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”.