Caligus pelamydis Krøyer, 1863

Boxshall, Geoff, 2018, The sea lice (Copepoda: Caligidae) of Moreton Bay (Queensland, Australia), with descriptions of thirteen new species, Zootaxa 4398 (1), pp. 1-172 : 107-109

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).

Figures

FIGURE 48. Caligus pelamydis Krøyer, 1863, female. A, habitus, dorsal; B, antenna, post-antennal process and maxillule drawn in situ; C, sternal furca; D, distal armature on exopod of leg 1; E, endopod of leg 2; F, exopod of leg 2; G, exopod of leg 3; H, leg 4. Scale bars:1.0 mm on A, 100 µm on B, E–G, 50 µm on C, D, 200 µm on H.