A review of the Caligus productus species group, with the description of a new species, new synonymies and supplementary descriptions

Abstract

The productus-group within the sea lice genus Caligus Müller, 1785 is characterised by the loss of two and the reduction or loss of the third of the three plumose setae normally carried on the posterior margin of the distal exopodal segment of the first swimming leg. We describe a new species, Caligus lethrinicola n.sp., from a lethrinid host collected in New Caledonia. We review the group and recognize 15 species as valid, including the new species. The type material of the three varieties of Caligus mauritanicus Brian, 1924 is re-examined and the var. temnodontis is here recognized as a distinct species, Caligus temnodontis Brian, 1924. The typical and miniscula varieties are recognised as synonyms of Caligus dakari van Beneden, 1892 and C. haemulonis Krøyer, 1863 respectively. Additional synonymies are proposed within the group. Supplementary observations are presented on the morphology of C. dakari, C. haemulonis and C. temnodontis. A brief differential diagnosis is presented for each of the 14 previously described valid species and a key to species has been constructed.

Discovery of the fish host of the ‘planktonic’ caligid Caligus undulatus Shen & Li, 1959 (Crustacea: Copepoda: Siphonostomatoida)

“…In the speciose genus Caligus, six species groups have been previously recognised (Cressey 1991, Boxshall and El-Rashidy 2009, Özak et al 2017, Boxshall 2018, Ohtsuka and Boxshall 2019. Following Cressey's criteria separating three species groups, with a 2segmented exopod of leg 4 defining one species group (Cressey 1991), we propose a newly-recognised species group, the C. undulatus group, defined by the following combination of characters (in line with Boxshall 2018): (1) leg 4 3-segmented, with IV spines on the compound distal exopodal segment; (2) three plumose setae on posterior margin of distal exopodal segment of leg 1; (3) outer spines on distal exopodal segment of leg 2 small or reduced; and (4) antenna with weak or well-developed process on proximal segment.…”

Two new species of the genus Caligus (Crustacea, Copepoda, Siphonostomatoida) from the Sea of Japan, with a note on the establishment of a new species group

“…Five distinct species groups within the genus Caligus were defined by Boxshall and El-Rashidy (2009) and Boxshall (2018), namely: C. bonito Wilson, 1905 (12 spp. based on Boxshall 2018), C. confusus Pillai, 1961 (15 spp.…”

Discovery of the male of the rare caligiform copepod Kabataia Kazachenko, Korotaeva & Kurochkin, 1972 (Copepoda: Siphonostomatoida), with a reconsideration of its phylogenetic affinities

“…In the caligiform families it is common to find sexual dimorphism in the form of the genital complex plus legs 5 and 6 which it bears, in abdominal segmentation, in the form of the antenna and the maxilliped. Sexual dimorphism also occurs, but less commonly, in the postantennal process (e.g., Boxshall & El-Rashidy 2009) and in the maxillule (e.g., Lepeophtheirus von Nordmann, 1832, see Dojiri & Ho 2013). However, the form of the dimorphism exhibited in the maxillule of Kabataia is unusual.…”