Cardiodectes asper, Uyeno, Daisuke & Nagasawa, Kazuya, 2010

Uyeno, Daisuke & Nagasawa, Kazuya, 2010, Three new species of the family Pennellidae (Copepoda: Siphonostomatoida) from gobiid fishes (Actinopterygii: Perciformes) in coastal waters of the western Pacific Ocean, Zootaxa 2687, pp. 29-44 : 33-38

Cardiodectes asper n. sp.

( Figs 4–7 )

Type material. Holotype, female ( NSMT –Cr 21193), ex Trimma grammistes (Tomiyama) ( Perciformes : Gobiidae ), off Akinohama (34°47’N, 139°23’E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan; 40 m depth; 18 March 2010 by O. Hoshino. Paratype, 1 female ( NSMT –Cr 21194), ex T. grammistes off Akinohama, Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan; 40 m depth; 18 March 2010 by O. Hoshino.

Description of postmetamorphic adult female. Body ( Fig. 5 A, B) 4093–4344 (4218 ± 177) long (n = 2), comprising large cephalothorax, neck region and trunk. Cephalothorax ( Fig. 6 A, B) slightly longer than wide [1488–1593 (1541 ± 74) × 1380–1422 (1401 ± 30)], bearing pair of anterior digitiform lobes, expanded laterally forming two pairs of rounded lobes, one small and one large; anterior process nodular and branching, covering anterior half of cephalothorax ( Fig. 5 A, B, C). Neck region ( Figs 5 C, 6A, B) narrow, bearing pair of lobes, 90o bending in middle. Trunk ( Fig. 5 A, B) longer than wide [2535–2664 (2599 ± 91) × 1581–1715 (1648 ± 94)], oval with convex posterior margin. Egg sac spiral ( Fig. 4 A, B) unicerate, originating at posterior lateral genital apertures.

Rostrum, antennules, and antennas situated closely to each other at anterodorsal surface of cephalothorax ( Fig. 6 C, D). Rostrum round ( Fig. 6 D), present between bases of antennules. Antennule ( Fig. 6 E) indistinctly segmented, bearing 8 setae mainly on anterior margin; distal tip bearing 8 setae, 4 setae sharing common base between 2 setae and 1 aesthetasc. Antenna ( Fig. 6 F) 3-segmented, chelate, typical pennellid; proximal segment with highly chitinous ridge on posterior surface; middle segment bearing pointed projection on inner medial margin; terminal segment claw-like with 1 small seta at base. Mouth tube on anterior part on ventral surface of cephalothorax. Maxillule ( Fig. 6 G) in form of knob, on laterally to base of mouth tube, bearing 3 modified setal elements, 1 blunt and 2 with slightly swollenbases. Maxilla ( Fig. 6 H) 3-segmented separated from mouth tube and maxillule by long gap; proximal segment with pointed process antero-medially; middle

segment ornamented with fine spinules posteriorly; terminal segment tongue-shaped, covered with fine

spinules on posterior surface. Maxilliped absent.

Legs 1 and 2 ( Fig. 7 A, B) biramous, situated centrally on cephalothorax ( Fig. 6 A, B). Leg 3 ( Fig. 7 C)

uniramous, situated behind lobe on neck; endopod absent. Armature formula of all three legs as follows:

Protopod Exopod Endopod

Leg 1 1–1 1–1; 7 0–0; 7

Leg 2 1–0 1–1; 7 0–0; 7

Leg 3 0–0 0–0; 6 ―

Protopod of legs 1 to 3 connecting with membranous structure to intercoxal sclerites.

Attachment site. The cephalothorax and neck region of the copepod were embedded in the musculature of the host’s head, while its trunk and egg sacs protruded into the water ( Fig. 4 A, B).

Remarks. The genus Cardiodectes currently comprises 12 species, which are separated into two groups, ‘medusaeus’ group and ‘rubosus’ group ( Izawa 1970; Bellwood 1981). The former contains 6 species, C. anchorellae Brian & Gray, 1928 , C. bellottii (Richiardi, 1882) , C. cristatus Shiino, 1958 , C. frondosus Schuurmans Stekhoven, 1937 , C. longicervicus Shiino, 1958 , and C. medusaeus (Wilson, 1908) , bearing an abdomen. The latter group consists of the remaining 6 species, C. boxshalli Bellwood, 1981 , C. hardenbergi Markevich, 1936 , C. krishnai Sebastian, 1968 , C. rotundicaudatus Izawa, 1970 , C. rubosus Leigh-Sharpe, 1934 , and C. spiralis Bellwood, 1981 , lacking an abdomen. As the new species lacks an abdomen, it belongs to the ‘rubosus’ group. The species is separated from C. boxshalli and C. krishnai by having 2 pairs of large lateral lobes on the cephalothorax ( Fig. 6 A). The trunk of C. hardenbergi , C. rotundicaudatus and C. rubosus is more than twice as long as wide, but the trunk of the new species is shorter than twice the width. The new species resembles C. spiralis but differs in the following characters: a well developed neck lobe ( Fig. 6 B)with leg 3 on the posterior part of the base, and the neck 90o bending in middle.

Etymology. The specific name of the new species, asper , refers to the rough cephalothorax with 6 lobes.

Figures

FIGURE 4. Cardiodectes asper n. sp., paratype NSMT – Cr 21194. A, a specimen of Trimma grammistes carrying the parasite which induced a swelling on the head (arrow); B, the dorsal region of the host’s head carrying the parasite. Scale bars: A, 2000 μm; B, 1000 μm.

FIGURE 5. Cardiodectes asper n. sp., female, holotype NSMT – Cr 21193. A, habitus, dorsal; B, habitus, lateral; C, cephalothorax and neck region, ventral. Scale bars: A, 2000 μm; B, 1500 μm; C, 700 μm.

FIGURE 6. Cardiodectes asper n. sp., female, holotype NSMT – Cr 21193. A, cephalothorax with digitiform processes removed, ventral, p 1 = leg 1, p 2 = leg 2, p 3 = leg 3; B, cephalothorax with digitiform processes removed and neck region, lateral, p 1 = leg 1, p 2 = leg 2, p 3 = leg 3; C, anterior part of cephalothorax with digitiform processes removed, dorsal; D, antennules, antennae and rostrum; E, antennule, posterior; F, antenna, anterior; G, maxillule; H, maxilla, anterior. Scale bars: A, B, D, 700 μm; C, 300 μm; E, H, 20 μm; F, 30 μm; G, 15 μm.

FIGURE 7. Cardiodectes asper n. sp., female, holotype NSMT – Cr 21193. A, leg 1; B, leg 2 (drawn from a paratype, NSMT – Cr 21194); C, leg 3 (drawn from a paratype, NSMT – Cr 21194). Scale bars: A, B, C, 50 μm.