Caligus laticaudus Shiino, 1960

Moon, S. - Y. & Kim, I. - H., 2012, Sea lice (Copepoda, Siphonostomatoida, Caligidae) new to Korea, including three new species, Journal of Species Research 1 (2), pp. 175-217 : 184-187

Caligus laticaudus Shiino, 1960

( Figs. 7, 8 )

Caligus laticaudus Shiino, 1960, p. 482 , figs. 5, 6; Pillai, 1961, p. 91, fig. 3; Lewis, 1968, p. 71, figs. 29, 30; Ho et al., 2000, p. 172, figs. 7-9; Ho and Lin, 2004, p. 194, figs. 101-103.

Material examined. 2¥¥, 2JJ from Evynnis japonica Tanaka , at Sagye in Jeju Island, M. K. Choe, 29 August 2009 ; 4¥¥, 1J from Evynnis japonica , at Aeweol in Jeju Island, M.-K. Choe, 22 October 2009 .

Female. Body ( Fig. 7A) 3.35 mm long. Cephalothoracic shield bcircular, 1.67× 1.67 mm; lunules relatively small; ventral rib of lateral zone bifucated distally; posterior sinus deep; posterolatyeral pit present. Fourth pedigerous somite, genital complex, and abdomen fused to form genitoabdomen. Region of Genital complex widest across distal two-thirds, wider than long, 706×894 µm. Abdominal region 529×424 µm, single-segmented but with rudimentary articulation line laterally near middle. Caudal ramus 158×129 µm, 1.22 times as long as wide, with 6 setae; inner margin with setules.

Antennule ( Fig. 7C) 317 µm long and 2-segmented; proximal segment occupying 68% length of antennule, with 25 setae; distal segment with 12 naked setae and 2 aesthetascs. Antenna ( Fig. 7D) 3-segmented; first segment lacking posterior process; second segment nearly quadrangular; third segment forming very long, weakly curved claw bearing 1 small seta proximally. Postantennal process small ( Fig. 7D) proximally bearing 2 papillae each tipped with 2 or 3 setules; another papilla located posterior to postantennal process tipped with 4 setules.

Mandible with 12 teeth distally. Maxillule consisting of anterior papilla bearing 3 small setae and posterior process bearing elongate distal tine. Maxilla ( Fig. 8A ) 2- segmented and rather broad; proximal segment (lacertus) unarmed; distal segment (brachium) with membrane (flabellum) at about 60% region of inner margin; calamus about 1.4 times longer than canna. Maxilliped ( Fig. 7E) 3- segmented; first segment (corpus) characteristically with large, tapering, inner proximal process; second segment (shaft) short, with 1 distal seta; third segment almost fused with second, forming strong claw. Sternal furca ( Fig. 7F) with moderately slender, slightly divergent tines bearing blunt tip.

Armature on rami of legs 1-4 as follows:

Leg 1: exopod 1-0; 3,1,3; endopod (vestigial)

Leg 2: exopod I-1; I-1; II,I,5; endopod 0-1; 0-2; 6

Leg 3: exopod I-0; I-1; III,4; endopod 0-1; 6

Leg 4: exopod I-0; I-0; III; endopod (lacking)

Leg 1 ( Fig. 7G) coxa with branched outer setule; basis with pinnate outer and inner setae; proximal exopodal segment with 1 small outer distal naked seta and row of setules on inner margin; distal segment with 4 naked distal setae and 3 inner pinnate setae; outermost distal seta much smaller than other distal setae; all of these 4 distal setae without setule (or not branched); endopod rudimentary, its tip slightly recurved and pointed. Leg 2 ( Fig. 7H) coxa with large seta on inner posterior margin; basis with small outer seta and 1 inner setule and membrane on inner part of posterior margin; second and third endopodal segments with patch of numerous minute spinules on outer surface. Leg 3 ( Fig. 8B ) protopod (apron) with several spinules on outer ventral surface; second exopodal segment with vestigial articulation line dividing regions of proximal 2 and distal 4 setae. Leg 4 ( Fig. 8C ) rather broad, protopod with small outer distal seta; exopod 3- segmented, with segments nearly similar in length; spines on first exopodal segment 135 µm; that of second segment 154 µm; 3 spines on third segment 169, 192, and 213 µm, respectively, from outer to inner; exopodal segments with row of minute spinues near base of spines; spines of exopodal segments marginated with narrow membranes. Leg 5 ( Fig. 8D ) represented by 1 and 3 small setae on knob and 1 setae on papila at posterolateral margin of genital complex.

A D B C F E H G

Male. Body ( Fig. 8E ) 2.66 mm long. Cephalic shield 1.49 × 1.54 mm. Genital complex 523×515 µm, with slightly convex lateral margins. Abdomen 300×315 µm. Caudal ramus 153×123 µm, 1.24 times as long as wide.

Antennule not examined. Antenna 3-segmented; second segment with 3 adhesion pads; third segment forming large, strongly curved claw bearing 1 large subsidiary claw proximally ( Fig. 8G ). Postantennal process larger and longer than that of female.

Mandible, maxillule, maxilla, maxilliped and sternal furca not different from those of female. Legs 1-4 also as in female. Leg 5 represented by 3 small setae on genital flap ( Fig. 8F ). Leg 6 absent.

Distribution and hosts. Indo-West Pacific. From Acanthurus olivaceus Bloch and Schneider in Eniwetok Atoll ( Lewis, 1968); Pagrus major (Temminck and Schlegel) in Japan ( Shiino, 1960); Parapristipoma trilineatum (Risso) and Lutjanus vita (Quoy and Gaimard) in Taiwan ( Ho et al., 2000); Polynemus heptadactylus Cuvier and Rhabdosargus sarba (Forskål) in India ( Pillai, 1961); and Evynnis japonica Tanaka in Korea (present study).

Remarks. Ho et al. (2000) mentioned six distinguishing characteristics of Caligus laticaudus as follows: 1) the corpus (first segment) of the maxilliped has a large, conical protrusion on the medial surface; 2) the terminal element of the first exopod lack accessory processes; 3) element 1 of the four terminal armatures of leg 1 exopod is short, only about one third of the length of other three elements which are subequal in length; 4) the 3-segment- ed exopod of leg 4 with the armature of I-0, I-0, III; 5) the terminal three spines on the exopod of leg 4 are subequal in length; and 6) the 2-segmented abdomen is short and broad, with its length less than twice the width. The first five characteristics are easily confirmed in Korean specimens. In the last characteristics the segmentation of the abdomen is, however, not distinct, almost obsolete in Korean specimens.

Figures

Fig. 8. Caligus laticaudus Shiino, female. A. maxilla. B. leg 3. C. leg 4. D. leg 5. Male. E. habitus, dorsal. F. urosome, ventral. G. second and third segments of antenna. Scales=A-C, G. 0.1 mm. D. 0.05 mm. E. 0.5 mm. F. 0.2 mm.