Caligus pelamydis Krøyer, 1863

(Fig. 48)

Material examined. 1♀ from Pomatomus saltatrix (Linnaeus, 1766) (TC17537) 24 June 2016, QM Reg. No. W53093.

Site on host. Unknown (in body wash).

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes; frontal plates with small lunules. Genital complex about 1.1 times longer than wide (Fig. 48A); abdomen elongate, about 3.0 times longer than wide, indistinctly 2-segmented, with anterior somite about 3.1 times longer than short anal somite; genital complex shorter than abdomen, with convex lateral margins narrowing anteriorly. Antenna without posterior process on proximal segment (Fig. 48B). Post-antennal process reduced, with vestigial tine; associated papillae multisensillate. Maxilliped of female with smooth myxal margin. Sternal furca with slightly incurved blunt-tipped tines. Distal exopodal segment of leg 1 with 3 plumose setae on posterior margin; distal margin spine 1 shorter than other spines; spines 2 and 3 with tapering tips without accessory processes (Fig. 48D); seta 4 shorter than spine 3. Leg 2 with patches of fine setules extending onto ventral surface of endopodal segments 2 and 3 (Fig. 48E); outer margin of first endopodal segment unornamented; outer spines on exopodal segments 1 and 2 aligned close to longitudinal axis of ramus (Fig. 48F); proximal spine on third exopodal segment naked, about 65% length of distal spine. Leg 3 with 3-segmented exopod; first segment bearing small straight spine with cuticular flange at base (Fig. 48G); second segment with small outer spine plus long inner seta; third segment with 3 spines increasing in length distally, plus 4 plumose setae. Leg 4 uniramous, 4-segmented (Fig. 48H); exopodal segments armed with I; I; III spines; each spine with elongate strip of membrane (modified pecten) on surface of segment adjacent to base. Body length of female 3.92 mm.

Remarks. This is a distinctive species characterized by its unusually long abdomen. It is a core member of the C. diaphanus -group. Caligus pelamydis is most frequently reported from scombrid hosts and has an almost cosmopolitan distribution (Cressey & Cressey, 1980) in the North and South Atlantic, Indian, and North and South Pacific Oceans. It has been recorded in Australian waters off New South Wales, on Euthynnus affinis, Sarda australis and Auxis sp. (Cressey & Cressey, 1980), and on Arripis trutta by Hutson et al. (2011). In Moreton Bay it was found on P. saltatrix; it has been reported previously from this host taken off the African coast in the South Atlantic (Capart, 1959).