A review of the genus Caligus (Copepoda: Caligidae) from South Africa

[摘要] English: The ichthyoparasitic and fish louse copepod genus, Caligus Müller, 1785, is the most abundantcopepod genus, found in almost any part of the world's oceans, with the exception of onefreshwater species. More than 315 nominal species have been described, of which only 26 specieshave been recorded off the coast of South Africa. Most of the information on this genus fromSouth Africa is limited to very old and often incomplete taxonomic descriptions. Of the 26 knownspecies of Caligus recorded from South Africa, only 15 species have reference material, either inthe collection of the South African Museum, or in the collection of the Aquatic ParasitologyResearch Group, University of the Free State, Bloemfontein. These 15 species are redescribed, andthe validity of each species is discussed. Additional morphological features for six species aregiven, based on studies with the aid of scanning electron microscopy. In addition to the speciesdescriptions, a synopsis of host/parasite and parasite/host is given. A key to all 15 species reviewedin the present study is included. The reference material of 15 species has disappeared, mainly dueto material on loan that got lost. These species will, however, remain as species recorded fromSouth Africa, until such time that their status can be validated. However, for the purpose of thisstudy, they are included as part of the South African fauna. Three of these 15 species, Caligusaffinis Heller, 1866, C. africanus Oldewage & Van As, 1989 and C. labracis Scott, 1902, have beenmisidentified. Specimens of the misidentified C. affinis were subsequently collected from the samehost, Pomatomus saltatrix (Linnaeus, 1766), in the present study, and a detailed description isincluded for this species (Caligus sp. B), but it is still uncertain whether this species is new.Caligus africanus is not a valid species and is therefore synonymised with Caligus tetrodontisBarnard, 1948. One new species (Caligus sp. A) has been collected from the Kob, Argyrosomusjaponicus (Temminck & Schlegel, 1843), and a fully illustrated description is supplied. With thedescription of this new species, as well as the inclusion of Caligus sp. B, the total number ofspecies recorded from the South African coast is 28. The genus Caligus can traditionally bedivided into four major species groups based on the segmentation and armature of the exopod of thefourth leg. In this study, a fifth group is proposed to include eight species (two species from thepresent study) with the same characteristic features of the exopod of the fourth leg. In this groupthe exopod of leg 4 is either one- or two-segmented, the first segment bearing a terminal spine andthe last segment bearing only two terminal spines. Future studies on the caligid copepods of SouthAfrica should involve molecular work, as this trend may be useful when species are found whichare close to each other, as was found in the present study with Caligus epinepheli Yamaguti, 1936,and C. rotundigenitalis Yu, 1933, or to explore phylogenetic relationships within the family to see whether a species belongs to another genus or not. During the course of the present study, whichstarted as an Honours project in 1997, four papers have been published in international journals.Various conference proceedings have also been published during the course of this study. Thispresent study forms a well-outlined reference for future studies on species of Caligus from SouthAfrica.

[发布机构] University of the Free State