Caligus furcisetifer Redkar, Rangnekar & Murti, 1949

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 : 66-67

Caligus furcisetifer Redkar, Rangnekar & Murti, 1949

( Fig. 29 )

Syn. Caligus lepeophtheiropsis Pillai, 1967

Material examined. 2♀♀ from Glaucostegus typus (Anonymous [Bennett], 1830) (TC17251) 18 January 2016; 1♀ QM Reg. No. W53072, 1♀ NHMUK 2017.272; 2♂♂ (TC17425) 22 January 2016; 1♂ QM Reg. No. W53073, 1♂ NHMUK 2017.273; 1♀ immature (TC 17360) 21 January 2016, 1♀ immature (TC 17416) 22 January 2016. Site on host. Body surface.

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes along margins of lateral zones of dorsal cephalothoracic shield; frontal plates with minute, inconspicuous lunules located laterally ( Fig. 29A ). Genital complex about as long as wide; abdomen small, 1-segmented, about 1.3 times longer than wide; genital complex about 2.7 times longer than abdomen. Antenna with tapering posterior process on proximal segment ( Fig. 29B ). Post-antennal process with large tapering tine; associated papillae multisensillate. Posterior process of maxillule simple; process on anterior sclerite extending over base of posterior process ( Fig. 29B ). Maxilliped of female with smooth myxal margin on proximal segment. Sternal furca with widely spaced, slightly divergent tines ( Fig. 29C ). Distal exopodal segment of leg 1 with 3 plumose setae on posterior margin; distal spine 1 stout, about as long as spine 2 ( Fig. 29D ); spine 3 shorter than spine 2, both with accessory process; seta 4 shorter than spine 3. Leg 2 with margin of endopodal segments 1 and 2 ornamented with setules; outer spine on exopodal segment 1 ( Fig. 29E ) directed obliquely over surface of ramus, spine on second segment aligned closer to longitudinal axis of ramus; proximal and distal outer spines on third segment well developed ( Fig. 29E ), with fine serrations along both margins. Leg 3 with well developed apron lacking distinctive ornamentation: rami located close together ( Fig. 29F ): exopod indistinctly 3-segmented; first segment with large tapering spine and inner plumose seta, second segment with outer spine and inner seta and incompletely separated from third segment, armed with 3 outer spines and 4 plumose setae. Endopod 2-segmented: first segment forming short velum and bearing inner seta; compound distal segment with 6 plumose setae. Leg 4 uniramous, 3-segmented; first exopodal segment with outer spine; second with 1 long and 2 short apical spines ( Fig 29G ); long spine more than 3 times longer than short spines. Mean body length of female 8.07 mm, range 7.63 to 8.50 mm (based on 2 specimens). Mean body length of male 6.68 mm, range 6.60 to 6.75 mm (based on 2 specimens).

Remarks. Caligus furcisetifer was originally described from India by Redkar et al. (1949), based on 3 females and 2 males collected from Eusphyra blochii (Cuvier, 1816) (as Sphyrna blochii ) caught off Bombay. However, it was poorly characterised so that Pillai (1967b, 1968) didn’t recognize it when he established a new species, C. lepeophtheiropsis Pillai, 1967 , to accommodate two females collected from an unidentified species of Pristis Linck, 1790 ( Pristidae ) caught at Trivandrum, India. Subsequently, in his monograph, Pillai (1985) placed C. lepeophtheiropsis in synonymy with C. furcisetifer .

The tiny size of the lunules on the frontal plates is a distinctive feature of this species. As Pillai (1968) commented, the lunules are inconspicuous and easily overlooked, and “the animal looks very much like a Lepeophtheirus ”. The species was discovered in Australian waters by Morgan et al. (2010) who found both sexes on the body surface and head of the critically endangered largetooth sawfish, Pristis microdon Latham, 1794, in the brackish reaches of the Fitzroy River (Western Australia) and the Leichhardt River opening into the Gulf of Carpentaria (Queensland). In Moreton Bay C. furcisetifer occurred only on Glaucostegus typus ( Rhinobatidae ). Although restricted to elasmobranch hosts, C. furcisetifer appears to exhibit relatively low host specificity having been recorded from three different orders, Carcharhiniformes , Pristiformes and Rajiformes .

Figures

FIGURE 29. Caligus furcisetifer Redkar, Rangnekar & Murti, 1949, female. A, habitus, dorsal; B, antenna, post-antennal process and maxillule drawn in situ; C, sternal furca; D, distal margin of exopod of leg 1; E, exopod of leg 2; F, rami of leg 3; G, leg 4. Scale bars: 1.0 mm on A, 200 µm on B, G, 100 µm onC, E, F, 50 µm onD.