Pseudanuretes chaetodontis Yamaguti, 1936

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 : 211-216

Pseudanuretes chaetodontis Yamaguti, 1936

( Figs. 27-29 )

Pseudanuretes chaetodontis Yamaguti, 1936, p. 16 , pl. 12, figs. 186-196; Kabata, 1965, p. 25, fig. 4D.

Material examined. More than 300¥¥ and 100JJ from gills of 4 Chaetodontoplus septentrionalis (Temminck and Schlegel) , at Gosan, Jeju Island, M.-K. Choe, 25 June 2009 .

Female. Body ( Fig. 27A ) small, 0.99 mm long. Cephalothoracic shield 675×585 µm, with thin membrane along lateral margins. Cephalic zone with 1 pair of setules and other minute setules on dorsal surface. Ventral rib of lateral zone almost straight but its distal end slightly curv- ed; posterior sinus absent; thoracic zone nearly rectangular, its posterior margin straight but with small process in middle. Fourth pedigerous somite not visible in dorsal view of body. Genital complex 311×456 µm, narrower distally, with posteromedian cleft. Abdomen absent. Caudal ramus ( Fig. 27C ) very small, 19×17 µm, with only 5 setae, one of them distinctly larger than others. Egg sac containing maximum of 3 eggs.

Antennule ( Fig. 27D ) 237 µm long and 2-segmented; proximal segment tapering, with curved, irregularly shap- ed setae (hardly countable); distal segment slender and curved, with 13 setae and 2 aesthetascs. Antenna ( Fig. 27E ) 3-segmented; first segment with elongate proximal process; second segment nearly ovoid and unarmed; third segment forming long, distally strongly bent claw bearing 1 seta and 1 claw-like process. Postantennal process ( Fig. 29F) rudimentary, with 3 papillae each tipped with 1 or 2 setules.

Mandible not examined. Maxillule consisting only of papilla bearing 2 unequal setae ( Fig. 27B ); posterior process absent ( Fig. 27E ). Maxilla ( Fig. 27G ) 2-segmented; proximal segment (lacertus) unarmed; distal segment (brachium) with subdistal flabellum on inner margin; canna much smaller than calamus and located subdistally. Large maxillary whip present nearby maxilla ( Fig. 27B, G ). Maxilliped ( Fig. 28A ) 3-segmented; first segment (corpus) gradually narrowed distally, with smooth lateral margins; second segment (shaft) short, distally with 1 seta and 1 small tubercle; third segment almost fused with second, forming strong claw. Sternal furca absent.

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,6; endopod 0-1; 8

Leg 3: exopod I-0; 8; endopod 0-0; 5

Leg 4: exopod I; endopod (lacking)

Leg 1 ( Fig. 28B ) basis with pinnate outer and inner setae. Proximal exopodal segment broad, with 1 outer distal naked seta and row of setules on inner margin; distal segment broader distally than proximally; three distal spines gradually larger from outer to inner, not bifurcate; 3 inner setae short and spiniform. Leg 2 ( Fig. 28C ) 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; first and second exopodal segments each with large outer spine extended far beyond end of exopod; second endopodal segment with rudiment of segmentation. Leg 3 ( Fig. 28D ) with 2-segmented rami; spine on first exopodal segment tapering and pointed; some of setae on second exopodal segment naked; first endopodal segment unarmed. Leg 4 ( Fig. 28E ) represented by 1 segment (19×12 µm) tipped by 1 spine (58 µm). Legs 5 and 6 ( Fig. 28F ) probably represented by 3 and 4 setae, respectively.

A D B C E

Male. Body ( Fig. 29A) 715 µm long. Cephalic shield resembling that of female. Urosome ( Fig. 29B) small. Genital complex ovoid, 132×202 µm. Abdomen short, much wider than long. Caudal ramus also much wider than long, 23×37 µm.

Antennule as in female. Antenna ( Fig. 29C) 3-segment- ed as in female; first segment unarmed; second segment with 2 small digitiform process distally; third segment bearing 2 proximal setae ( Fig. 29C) and 4 claws (2 of them larger and remaining 2 small) ( Fig. 29D). Postantennal process as in female.

Maxillule and maxilla as in female. Maxilliped ( Fig. 29E) with 2 prominent, digitiform process on inner margin of first segment.

Legs 1-4 as in female. Leg 5 represented by ventrolateral lobe tipped by 4 setae ( Fig. 29B). Leg 6 represent- ed by 2 setae on posterior end of genital flap ( Fig. 29B).

Distribution and hosts. From Chaetodon sp. in Japan ( Yamaguti, 1936), Chaetodontoplus personifer (McCulloch) in Australia ( Kabata, 1965), and Chaetodontoplus septentrionalis (Temminck and Schlegel) in Korea (present study).

Remarks. We found more than a hundred specimens of this parasite on each individual of the host fish C. septentrionalis . This high prevalence contrasts to the previous observations of only six females by Kabata (1965) in Australia and ten females by Yamaguti (1936) in Japan.

Figures

Fig. 27. Pseudanuretes chaetodontis Yamaguti, female. A. habitus, dorsal. B. cephalic area, ventral. C. caudal ramus, ventral. D. antennule. E. antenna and maxillule. F. postantennal process. G. maxilla and maxillary whip. Scales=A, B. 0.1 mm. C-G. 0.02 mm.

Fig. 28. Pseudanuretes chaetodontis Yamaguti, female. A. maxilliped. B. leg 1. C. leg 2. D. leg 3. E. leg 4. F. legs 5 and 6. Scales=A. 0.05 mm. B-F. 0.02 mm.