Metacaligus trichiuri ( Krøyer, 1863 ) Kroyer, 1863

Hayes, Polly, Justine, Jean-Lou & Boxshall, Geoffrey A., 2012, The genus Caligus Müller, 1785 (Copepoda: Siphonostomatoida): two new species from reef associated fishes in New Caledonia, and some nomenclatural problems resolved, Zootaxa 3534, pp. 21-39 : 37

Caligus trichiuri Krøyer, 1863

This species was originally described based on a male from Trichiurus lepturus Linnaeus, 1758 [as Trichiurus haumala ] collected in the Indian Ocean ( Krøyer, 1863). The illustrations provided by Krøyer (1863) include figures of the male genital complex and abdomen, the antennule and lunule, the mouth tube and maxillules in situ, the maxilliped, the distal exopodal segment of the first swimming leg, and the tip of the fourth leg (1863: plate IV, figs 2a–f).

The precise form of the armature of the distal segment of the exopod of leg 1 is very distinctive and is shared with the species of Metacaligus Thomsen, 1949 (cf. Ho & Bashirullah, 1977). The relative lengths of the male genital somite, free abdominal somites and caudal rami of C. trichiuri correspond exactly with those of Metacaligus uruguayensis Thomsen, 1949 . By comparison, the abdominal somites of Metacaligus latus Ho & Lin, 2002 are short, whereas those of M. unguidentatus (Rangnekar & Murti, 1950) are much more elongate. The male of Metacaligus rufus ( Wilson, 1908) is unknown but this species has been recorded only from the marine catfish Bagre marinus (Mitchill, 1815) [as Felichthys marinus ] on the Atlantic coast of the USA ( Wilson, 1908).

We recognise Caligus trichiuri and Metacaligus uruguayensis to be the same species, a parasite primarily of the cutlassfish Trichiurus lepturus , although it has also been reported from Lobotes surinamensis (Bloch, 1790) ( Ho & Lin, 2004) . Caligus trichiuri is the oldest available name for this taxon, so Caligus (Metacaligus) uruguayensis becomes a junior subjective synonym. The valid name for this taxon is Metacaligus trichiuri ( Krøyer, 1863) new combination, although we consider the validity of the genus Metacaligus to be doubtful and in need of reassessment.