Pseudocaligus longipes, Moon & Kim, 2012

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 : 190-193

Pseudocaligus longipes n. sp.

( Figs. 11 , 12 )

Material examined. 1¥, 1J from gills of Siganus fuscesens (Houttuyn) , at Sagye, Jeju Island, M.-K. Choe, 16 August 2009. Holotype (¥: antennule, maxilliped and leg 1 of right side and left and right leg 4 dissected out) and allotype (antenna, maxilliped and leg 4 of right side dissected out) have been deposited in the National Institute of Biological Resources, Incheon. Dissected appendages are kept in the collection of the junior author.

Female. Body ( Fig. 11A ) narrow, 1.98 mm long. Cephalothoracic shield longer than wide, 1.19× 0.84 mm, with thin lateral membrane; thoracic zone extending far beyond lateral zone; ventral rib of lateral zone short, linear, with indistinct distal end; posterolateral pit present; posterior sinus shallow. Fourth pedigerous somite short and fused with genital complex. Genital complex large, 600 ×669 µm, with rounded anterolateral and posterolateral corners. Abdomen short 105×154 µm, 1-segmented, and gradually narrowed distally. Caudal ramus 98×46 µm, 2.13 times as long as wide, with 6 setae, and setules on distal half of inner margin.

Antennule ( Fig. 11C ) 185 µm long and 2-segmented; proximal segment occupying 63% length of antennule, with 26 pinnate and 2 naked setae; distal segment with 12 naked setae and 2 aesthetascs. Antenna 3-segmented ( Fig. 11D ); first segment with large, tapering and pointed proximal process; second segment nearly quadrangular; third segment forming large, distally strongly bent claw bearing 2 small setae. Postantennal process with 2 papillae each tipped with 2 setules; another papilla located posterior to postantennal process tipped with 2 setules; small claw-like element present posterior to postantennal process ( Fig. 11D ).

Mandible with 12 teeth distally. Maxillule consisting of anterior papilla bearing 3 unequal setae and short, strongly tapering posterior process ( Fig. 11D ). Maxilla ( Fig. 11E ) 2-segmented; proximal segment unarmed; slender distal segment distinctly longer than proximal segment, with small membrane (flabellum) at 67% region of inner margin; calamus slightly longer than canna. Maxilliped ( Fig. 11F ) 3-segmented; first segment unarm- ed; second segment with 1 distal seta; third segment forming strongly curved claw, much shorter than second segment. Sternal furca ( Fig. 12A ) with incurved tines bearing transparent flange on outer margin; tines shorter than basal part of sternal furca.

Armature on rami of legs 1-4 as follows:

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

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

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

Leg 4: exopod 2; endopod (lacking)

Leg 1 ( Fig. 11G ) basis with pinnate outer and inner setae. Proximal exopodal segment fusiform, widest in middle, with 1 small outer distal naked seta and row of setules on inner margin; three distal spines on distal segment gradually shorter from outer to inner, inner two of them each bearing seta; distal seta small and naked. Endopod vestigial and tapering. Leg 2 ( Fig. 11H ) coxa with large seta on inner posterior margin and 1 setule inner ventral surface; basis with small outer seta and 1 inner setule and membrane on inner part of posterior margin; outer spines on first and second exopodal segments large and denticulate along outer (distal) margin. Leg 3 ( Fig. 12B ) protopod (apron) with broad membrane on outer and inner margins; spine on first exopodal segment bearing hyaline flange along outer margin; proximal spine on third exopodal segment rudimentary, much smaller than distal spines. Leg 4 ( Fig. 12C ) protopod 67×28 µm, with outer distal seta; exopod 1-segmented 61×18 µm, 3.39 times as long as wide, with 2 distal setae of 41 µm (outer) and 90 µm (inner); both setae bearing spinules on margins. Leg 5 represented by 1 knob tipped by 1 seta and another distal knob tipped by 2 setae on posterolateral area of genital complex.

Male. Body ( Fig. 12D ) larger than female, 2.22 mm long. Cephalic shield resembling that of female. Urosome ( Fig. 12E ) rather narrow. Genital complex 404×342 µm. Abdomen 1-segmented and 188×212 µm. Caudal ramus 173×92 µm, 1.88 times as long as wide.

Antennule as in female. Antenna ( Fig. 12F ) 3-segment- ed as in female; first segment unarmed and distinctly narrowed distally; second segment expanded proximally, with 2 small adhesion pads; third segment with 2 proximal setae and forming strong claw bearing 1 denticle. Postantennal process bearing papillae tipped with 2 or 3 setules.

Mandible, maxillule and maxilla as in female. Maxilliped ( Fig. 12G ) with proximal protuberance tipped with 1 small seta. Sternal furca as in female.

Legs 1-4 also as in female. Leg 5 represented by lobe bearing 3 setae ( Fig. 12H ). Leg 6 represented by 2 small setae on genital flap ( Fig. 12H ).

Etymology. The specific name longipes is derived from the Latin longus (long) and pes (foot). It alludes to the elongate exopod of leg 4 of the new species.

Remarks. Nine species are currently known in the genus Pseudocaligus . Of these, only two species, P. fistulariae Pillai, 1961 and P. uniartus Ho et al., 2004 , are known to have two-segmented leg 4 (protopod and one-segmented exopod), as the new species.

Pseudocaligus longipes n. sp. differs from P. fistulariae in having a short, one-segmented abdomen (vs. elongate and two-segmented in P. fistulariae ), seven elements with the armature of III,1,3 on the distal exopodal segment of leg 1 (vs. five elements with armature of III,1,1 in P. fistulariae ), four setae on the distal endopodal segment of leg 3 (six setae in P. fistulariae ), smaller body size (vs. larger body size, length 5.1 mm in the female of P. fistulariae cf. Pillai, 1961), and different configuration of the genital complex (which is longer than wide in P. fistulariae ). Pseudocaligus fistulariae was recorded as parasite of Fistularia villosa Kluzinger in India ( Pillai, 1961).

The new species also differs from P. uniartus in having seven elements on the third exopodal segment of leg 3 with the armature of III,4 (vs. III, 3 in P. uniartus ), four setae on the distal endopodal segment of the same leg (vs. three setae in P. uniartus ), more slender caudal ramus which is 2.13 times as long as wide (1.11 times as long as in P. uniartus ), and elongate exopod of leg 4 which is 3.39 times as long as wide (only slightly longer than wide in P. uniartus ). Pseudocaligus uniartus was recorded as a parasite of Siganus guttatus (Bloch) and Lutjanus argentimaculatus (Forsskål) both cultured in the Philippines (Ho et al., 2004).

Figures

Fig. 11. Pseudocaligus longipes n. sp., female. A. habitus, dorsal. B. abdomen, ventral. C. antennule. D. antenna, postantennal process, and maxillule. E. maxilla. F. maxilliped. G. leg 1. H. leg 2. Scales=A. 0.2 mm. B. 0.1 mm. C-H. 0.05 mm.

Fig. 12. Pseudocaligus longipes n. sp., female. A. sternal furca. B. leg 3. C. leg 4. Male. D. habitus, dorsal. E. urosome, dorsal. F. antenna. G. maxilliped. H. legs 5 and 6. Scales=A-C, F-H. 0.05 mm. D. 0.5 mm. E. 0.1 mm.