Caligus malabaricus Pillai, 1961

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 : 84

Caligus malabaricus Pillai, 1961

( Fig. 36 )

Material examined. 1♀ from Hyporhamphus regularis ardelio (Whitley, 1931) (TC 17757), 30 June 2016, QM Reg. No. W53081.

Site on host. Floor of mouth.

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes along lateral zones of dorsal cephalothoracic shield; frontal plates with large lunules. Genital complex with constricted anterior region ( Fig. 36A ); about 1.1 times longer than wide, and about 1.4 times longer than abdomen. Abdomen about 2.7 times longer than wide, indistinctly 2-segmented, first segment about 3.5 times longer than second. Genital complex and abdomen together about 1.4 times longer than cephalothorax. Antenna with posterior process on proximal segment ( Fig. 36B ). Post-antennal process with curved tine; associated papillae bisensillate, papilla on ventral cephalothoracic surface trisensillate. Posterior process of maxillule simple ( Fig. 36B ). Maxilliped of female with 2 small processes on myxal surface. Sternal furca with divergent tines with truncated tips ( Fig. 36C ). Distal exopodal segment of leg 1 ( Fig. 36D ) with 3 plumose setae on posterior margin; distal spine 1 markedly longer than other spines; spines 2 and 3 each with accessory process; seta 4 unilaterally plumose, longer than spine 1 and longer than segment. Leg 2 ornamented with strong spinules along outer margins of endopodal segments 1 and 2 ( Fig. 36E ); outer spines on exopodal segments 1 and 2 aligned obliquely across surface of ramus ( Fig. 36F ); proximal outer spine on third segment small, bilaterally serrate, distal spine twice as long and with membranes bilaterally. Leg 3 apron with ornamentation of fine spinules laterally and area of spinules medially; exopod 3-segmented ( Fig. 36G ); first exopodal segment with slightly curved outer spine, without inner seta; second with outer spine and inner plumose seta; third with 3 outer spines and 4 plumose setae. Leg 4 uniramous, 3-segmented ( Fig. 36H ); first and second exopodal segments armed with I and IV spines, respectively. Body length of female 3.71 mm.

Remarks. This species was established by Pillai (1961) based on two females collected from the buccal cavity of Tylosurus crocodilus caught off Trivandrum, India. It was next reported from Ablennes hians (Valenciennes, 1846) caught in the Torres Strait, off Northern Australia, by Cressey & Collette (1970) who noted that the female was ornamented with paired patches of fine spinules posterolaterally on the anal somite. The Indian females were 4.4 mm in length ( Pillai, 1961), whereas the Australian females were smaller, ranging in length from 3.60 mm to 4.13 mm. These are the only published records of C. malabaricus and both are from belonid hosts.

The Moreton Bay female from Hyporhamphus regularis ardelio was dark brown in colour and it retained this coloration even after preservation in ethanol. It was 3.71 mm in length and agreed with the description of Pillai (1961) in detailed features of the paired appendages, such as the configuration and ornamentation of the setal elements on the distal exopodal segment of leg 1, the size and alignment of the spines on the exopods of legs 2 and 4, and the shape and ornamentation of the antenna, post-antennal process and maxilla. The denticles along the margin of the second endopodal segment of leg 2 are shown by Pillai (1961: Fig. 13L ) as stouter than in the Moreton Bay female, but this difference may be due to the style of illustration. The genital complex and abdomen illustrated by Pillai (1961) are both broader than in the Moreton Bay female, generating some uncertainty about this identification. The only supplementary illustration of C. malabaricus , provided by Cressey & Collete (1970: Fig. 118), confirms that the 2-segmented abdomen has a broad anterior somite, more than twice as wide as the small anal somite. In the Moreton Bay female the anterior somite is relatively narrower ( Fig. 36A ), only 1.4 times wider than the anal somite, however, close examination reveals that its surface is unusually wrinkled which I interpret as evidence that the abdomen in this species, as well as the genital complex, might vary according to the reproductive state of the female. Because of this, the identification of this female as C. malabaricus is tentative, and any future revision should take into consideration the additional, similar-looking material from belonids, reported by Cressey & Collette (1970) as Caligus species A, C and D.

Figures

FIGURE 36. Caligus malabaricus Pillai, 1961, female. A, habitus, dorsal; B, antenna, post-antennal process and maxillule drawn insitu; C, sternalfurca;D, distalsegment of exopodof leg 1; E, endopod of leg 2;F, exopodof leg 2;G, exopodof leg 3; H, leg 4. Scale bars: 1.0 mm on A, 100 µm on B, E–H, 50 µm on C, D.

FIGURE13.Caligus abigailaesp. nov., paratype female.A, habitus,dorsal; B,rightfifth legat posterolateral cornerof genital complex, ventral; C, antenna and post-antennal process, drawn in situ; D, maxillule; E, sternal furca; F, leg 1; G, exopod of leg 2; H, endopod of leg 2. Scale bars: 0.5 mm on A, 50 µm on B, E, 100 µm on C, D, F–H.