Lepeophtheirus lagocephali Pillai, 1963

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 : 144-146

Lepeophtheirus lagocephali Pillai, 1963

( Fig. 68 )

Material examined. 3♀♀ from Lagocephalus lunaris (Bloch & Schneider, 1801) (TC17899) 5 July, 2016, QM Reg. No. W53124; 1♀ (TC17897) 5 July 2016, 1 ovigerous ♀ (TC17905) 5 July 2016, 1 ovigerous ♀, 4♀♀ immature (TC 17944) 6 July 2016, NHMUK Reg. Nos 2017.343–345.

Site on host. Body surface.

Differential diagnosis. Cephalothorax dorsoventrally flattened with well-developed marginal membranes along lateral margins of dorsal cephalothoracic shield; frontal plates lacking lunules. Genital complex quadrangular ( Fig. 68A ), just (1.04 times) longer than wide; genital complex about 50% length of cephalothorax; abdomen small, less than 20% of length of genital complex, not clearly delimited from genital complex; caudal rami carried on posterior margin of abdomen, either side of anal slit. Antenna with small, weakly developed process on proximal segment ( Fig. 68B ). Tine of post-antennal process short and straight; associated papillae unisensillate. Posterior process of maxillule bifid, with tapering inner tine and slender outer tine ( Fig. 68B ). Sternal furca with straight, divergent, acutely tapering tines ( Fig. 68C ). Distal exopodal segment of leg 1 with 3 plumose setae on posterior margin; distal margin spines 1, 2 and 3 similar in length ( Fig. 68D ); spines 2 and 3 each with accessory process and ornamented with finely serrate membranes; seta 4 just longer than spine 3, ornamented with tiny spinules along one margin. Leg 2 with 3-segmented rami: exopodal segments 1 and 2 armed with straight, bilaterally serrate spines directed disto-laterally away from longitudinal axis of ramus; third exopodal segment with large proximal outer spine overlying larger distal outer spine ( Fig. 68E ). Leg 3 with well developed apron lacking distinctive ornamentation; rami originating closely together ( Fig. 68F ): endopod 2-segmented, first segment with very slight lateral expansion forming small velum, armed with inner plumose seta; compound distal segment with only 5 plumose setae: exopod 3-segmented; first segment armed with straight outer spine directed obliquely across surface, plus inner plumose seta; second segment with outer spine and inner seta; third with 3 outer spines and 4 plumose setae. Leg 4 uniramous, 4-segmented ( Fig. 68G ); exopodal segments bearing I; I; III spines: proximal spine on exopod very small, apical claw more than 3 times longer than adjacent distal spines. Mean body length of female 4.85 mm, range 4.39 to 5.10 mm (based on 4 specimens).

Remarks. The form of leg 4 in L. lagocephali is typical for the majority of Lepeophtheirus species, with a 3- segmented exopod and a I, I, III formula (with the proximal spine minute). The distinctive features of this species include the short abdomen in combination with the configuration of the distal spines on the exopod of leg 1 plus the reduced setation of leg 3. The compound distal endopodal segment of leg 3 bears only 5 plumose setae ( Fig. 68F ) rather than 6, as is typical for the majority of Lepeophtheirus species.

Pillai (1963) based his description of this species on material collected from Lagocephalus inermis caught off Kerala, India . In Moreton Bay, this copepod utilizes L. lunaris and this constitutes a new host record as well as a first record from Australian waters.

Figures

FIGURE 68. Lepeophtheirus lagocephali Pillai, 1963, female. A, habitus, dorsal; B, antenna, post-antennal process and maxillule drawn in situ; C, sternal furca; D, setation elements on distal margin 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, E, G, 100 µm on C, F, 50 µm on D.