Caligus truttae Giard, 1890

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 : 564

Caligus truttae Giard, 1890

This species name was proposed for a Caligus specimen collected on sea trout (as Salmo trutta Linnaeus, 1758 ) caught in the estuary of the river Wimereux on the channel coast of northwestern France ( Giard, 1890). Giard (1890) noted that sea trout were frequently infected by “ Caligus rapax Milne Edwards, 1840 ” but commented that this caligid species has been recorded from a “large diversity of fishes including elasmobranchs”. He considered that it was inadequately described and suggested that the parasite found on this salmonid at Wimereux was a distinct species which he named Caligus truttae .

The bulk of Giard’s (1890) short paper was devoted to discussion of the application of the study of algae to the understanding of the behaviour of the sea trout. He outlined the timing of the life cycle of S. trutta and noted the seasonality of infection by “ Caligus truttae ” and the presence of settlement stages of Laminaria species, as well as attached diatoms and the monogenean Udonella Johnston, 1835 and its egg capsules. However, nowhere does Giard (1890) provide any descriptive morphological data or illustration associated with the name of his proposed new species. We therefore consider Caligus truttae Giard, 1890 to be a nomen nudum.