Caligus longipedis Bassett-Smith, 1898

(Fig. 35)

Syn: Caligus lucidus Heegaard, 1962

Material examined. 1♀ from Gerres sp. juveniles (caught by seine net from shore at Adams Beach, North Stradbroke Island) on 26 June 2016, QM Reg. No. W53080.

Site on host. Body surface.

Differential diagnosis. Cephalothorax dorsoventrally flattened with slightly irregular lateral margins (Fig. 35A) bearing well-developed marginal membranes; frontal plates with well-developed lunules. Genital complex about 1.6 times wider than long, produced into slight postero-lateral lobes; abdomen 1-segmented, about 1.3 times longer than wide; genital complex about 2.0 times longer than abdomen. Caudal rami about 2 times longer than wide. Antenna with posterior process (Fig. 35B) on proximal segment; distal subchela with striations on surface. Post-antennal process weakly curved; associated papillae unisensillate, sensillae long (Fig. 35C). Posterior process of maxillule simple, ornamented with surface striations (Fig. 35D). Maxilla with distal margin of brachium spinulate (Fig. 35E). Maxilliped of female with smooth myxal margin and short claw on subchela. Sternal furca with short, spatulate tines (Fig. 35F). Distal exopodal segment of leg 1 with 3 plumose setae on posterior margin; distal spine 1 simple and slightly shorter than other spines; spines 2 and 3 each with accessory process; seta 4 about 1.4 times longer than spines 2 and 3. Leg 2 with patches of setules extending onto surface of endopodal segment 2; segment 3 with raised patch of setules and 2 striated crescentic membranes on surface (Fig. 35G); outer spines on exopodal segments 1 and 2 aligned obliquely across surface of ramus. Leg 3 exopod 3-segmented; first segment with short almost straight spine ornamented with lateral strip of membrane and ornamented with membranous flange along outer margin, lacking inner seta. Leg 4 uniramous, 3-segmented (Fig. 35H); exopodal segments 1 and 2 with I and III long spines, respectively, each ornamented with narrow strips of smooth membrane. Body length of female 5.36 mm.

Remarks. This is a large and distinctive species of Caligus readily characterized by the possession of posterolateral lobes on the female genital complex, in combination with the elongate spines on the exopod of leg 4, the spatulate tines of the sternal furca, the ornamentation of the distal margin of the maxilla and the presence of crescentic membranes on the third segment of the endopod of leg 2. The male described by Ho & Lin (2004) is not conspecific with the female; the true male of C. longipedis was redescribed by Venmathi Maran et al. (2009).

Caligus longipedis is widely distributed: having been reported from across the Atlantic and the Indo-Pacific, including from Aden (Bassett-Smith, 1898a), Belize (Cressey, 1991), Mexico (Shiino, 1959, as C. amplifurcus Pearse, 1953; Morales-Serna et al., 2014), Florida (USA) (Pearse, 1953, as C. amplifurcus), Hawaii (Lewis, 1967), India (Gnanamuthu, 1950, as C. scabiei), Japan (Kubota & Takakuwa, 1963), Korea (Moon & Kim, 2012), Malaysia (Venmathi Maran et al., 2009), and Taiwan (Ho & Lin, 2004). This species has also been reported from Australian waters by Heegaard (1962), under the name Caligus lucidus (Table 1), and by Catalano & Hutson (2010) from Arripis truttaceus .

This copepod is most commonly reported as a parasite of carangids including Caranx melampygus, C. hippos, C. caninus, C. crysos (Mitchill, 1815), C. lugubris Poey, 1860, Carangoides chrysophrys (Cuvier, 1833), Megalaspis cordyla (Linnaeus, 1758), Pseudocaranx dentex (Bloch & Schneider, 1801), Selene vomer (Linnaeus, 1758) and Seriola sp. However, it has been reported from a range of other fish families including: Acanthuridae, Haemulidae, Ostraciidae, Paralichthyidae, Pomacanthidae, Scaridae and Serranidae (Cressey, 1991) . In Australian waters Heegaard (1962) recorded it from Nelusetta ayraud (Quoy & Gaimard, 1824) (as Cantherhines ayraud) ( Monacanthidae) at Cape Hawke (New South Wales); Catalano & Hutson (2010) reported it from Arripis truttaceus off the southeastern coast, and the new record from Moreton Bay was from juvenile Gerres (Gerreidae) . Caligus longipedis is known to be a pest of the carangid Pseudocaranx dentex cultured in Japanese waters (Ogawa, 1992).