Caligus undefined-2

Caligus sp. 2 (Figs 31A – 32E) Host: Coryphaena hippurus Linnaeus (Coryphaenidae: Carangiformes) Locality: Off west coast South Africa (Atlantic Ocean) Material examined: 1♀ Material collected: 1♀ from C. hippurus Adult female (Fig. 31A) cephalothorax more than half of total length; genital complex slightly longer than wide, posterolateral corners lobate; abdomen small, 1-segmented, about ⅓ length of genital complex; antenna (a2) with tapering proximal process (arrowed), claw strongly curved (Figs 31B, C); post-antennal process (pap) tine weakly curved, blunt-ending (Figs 31B, C); maxillule with dentiform posterior process (mpp) slightly curved, blunt tip surrounded by marginal flange (Figs 31B, C, D); sternal furca (sf) with divergent, blunt-ended tines slightly curved inwards distally, surrounded by marginal flange (Fig. 31E); leg 1 last exopodal segment with 3 posterior pinnate setae (ps), terminal seta 4 (4) longer than terminal spines 1–3 (Figs 31F, 32A), spine 2 (t2) and 3 (t3) with accessory processes (Fig. 32A); leg 2 exopodal segment 1 and 2 distolateral spines (arrowed) lying obliquely over surface of ramus (Fig. 32B), endopodal segments with setules (arrowed) along outer margins (Fig. 32C); leg 3 exopodal segment 1 distolateral spine (ds) curved, slightly shorter than segment 2 (Fig. 32D); leg 4 3-segmented with I, IV spines, medial terminal spine (IV) about twice as long as distolateral spine (II) (Fig. 32E). Remarks: This specimen is slightly smaller (3.6 mm) than C. mulli reported before (4.2 mm) with the genital complex of this specimen about 1.1 mm long and slightly longer than wide while that of C. mulli is about 1.7 mm long and about 1.5 times longer than wide. The post-antennal process tine is not conspicuously surrounded by a marginal flange (see Fig. 31C) while in C. mulli it is (see Fig. 29B). Leg 2 exopod distolateral spines on the first and second segments are lying slightly obliquely over the surface of the rami with the spine on the first segment almost reaching the middle of the last segment and the spine on the second segment also reaching about the middle of the last segment (see Fig. 32B) while in C. mulli the spines are lying obliquely over the surface of the rami with the spine on the first segment barely reaching into the next segment (see Fig. 29F). Leg 3 first exopodal segment distolateral spine in the current specimen is curved, almost reaching the articulation between segments 2 and 3 (see Fig. 32D) while in C. mulli it is less curved and slightly shorter (see Fig. 30B). Spines on leg 4 are very similar with the lateral spines in the current specimen maybe slightly longer (see Fig. 32E) than those in C. mulli (see Fig. 30C). Caligus sp. 2 does not fall within one of the eight established Caligus groups. Comparing it with the remaining species, it does not seem like any of the described species has the combined suit of features. Firstly, the posterolateral lobes of the genital complex together with the small abdomen are features not often encountered. Secondly, the combined features of legs 1–4 are also rarely encountered amongst the compared species. The shape of the genital complex almost resembles that of C. deformis Brian (Özak pers. comm.) as do the structure of leg 4, but the body proportions are different and the original description somewhat vague (Brian 1924). Therefore, this may be a new species, but with only one available specimen it will remain as Caligus sp.