Caligus undefined-1

Caligus sp. 1 (Figs 16A – 17E) Host: Galeorhinus galeus (Linnaeus) (Carcharhiniformes: Triakidae) Locality: Off west coast South Africa (Atlantic Ocean) Material examined: 1♀ Material collected: 1♀ from G. galeus Adult female (Fig. 16A) 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, posterior margin protruded with slit-like anus (Fig. 16B); antenna (a2) with small proximal process (arrowed) (Fig. 16C), claw strongly curved (Figs 16C, D); post-antennal process (pap) tine weakly curved, blunt-ending (Figs 16C, D); maxillule with dentiform posterior process (mpp) slightly curved, blunt tip (Figs 16C, D); sternal furca with short, divergent, blunt-ended tines curved inwards distally (Figs 16D, E); leg 1 last exopodal segment with 3 posterior pinnate setae, terminal seta 4 (4) distinctly longer than terminal spines (ts) 1–3, almost as long as segment, spines 2 and 3 with accessory processes (ap) (Fig. 16F) longer than spine 1; leg 2 exopod segments 1 and 2 distolateral spines (arrowed) lying obliquely over surface of ramus, not reaching the inner setae (Fig. 17A), endopodal segment 2 with setules (s) along outer margin, endopodal segment 3 with patch of denticles (d) proximally on outer margin (Fig. 17B); leg 3 exopodal segment 1 distolateral spine (ds) slightly curved, not reaching articulation between segments 2 and 3 (Fig. 17C); leg 4 3-segmented with I, III spines (arrowed) respectively, increasing in length from outer to inner (Fig. 17D). Remarks: This specimen exhibits all the distinguishing features of the C. macarovi -group except the marginal serrations on the distal margin of the maxilla brachium (cf. Fig. 63G in Boxshall (2018)) that was not observed (arrowed) (Fig. 17E) and leg 1 exopod spines 1 to 3 that is not of similar length, but with spine 1 about half the length of spines 2 and 3 (see Fig. 16F). Thus, it was compared with the descriptions and/or illustrations of all 42 species currently in this group (see Table 5 in Boxshall 2018). Although the habitus is the closest to that of C. pseudokalumai Lewis it differs in many other aspects from this species i.e. the total length of the current specimen (3.43 mm vs 2.89 mm) the size of the proximal process on the antenna, the structure of the maxillule dentiform posterior process, the shape of the sternal furca tines, the length of the leg 1 last exopod terminal spine 1 and also the length of the spines on leg 4 (cf. Lewis 1968). Additionally, the only species reported from an elasmobranch that forms part of the C. macarovi -group is C. punctatus Shiino (Tang & Newbound 2004). The current specimen differs in the structure of the habitus (see Fig. 1 in Shiino (1955)) as well as in total length (3.43 mm vs 2.49 mm) from C. punctatus as well as in the morphology of the antenna proximal process, maxilliped, length of leg 1 last expodal terminal spines, leg 2 length of exopodal spines, leg 4 length of spines (cf. Shiino 1955). The structure of legs 1 and 4 is similar to that of C. tumulus Hayes, Christison, Vaughan, Smit & Boxshall, 2021 (see Fig. 6G in Hayes et al. (2021)), but the current specimen clearly differs from C. tumulus in many other aspects of the morphology (e.g. habitus, antenna proximal process, maxillule posterior process, maxilliped, sternal furca) (cf. Hayes et al. 2021). Therefore, this may be a new species, but with only one available specimen it will remain as Caligus sp.