Clavellisa chinensis ( Yü, 1933 )

Moon, Seong Yong, 2019, New records of Colobomatus mylionus Fukui, 1965 and Clavellisa chinensis (Yü, 1933) (Crustacea: Copepoda) parasitic on marine fish of Korea, Journal of Species Research 8 (4), pp. 373-379 : 376-378

Clavellisa chinensis ( Yü, 1933)

Korea name: Ung-eo-gin-mok-teol-beol-rae ȃqŭệflḏNj (ljḡ) ( Fig. 3 )

Epiclavella chinensis Yü, 1933, p. 134 , pl. 8, figs. 1-7.

Material examined. Three females (NIBRIV0000293 065, one vial), off Haenam-gun (34°19 ʹ 24 ʺ N, 126°28 ʹ 07 ʺ E), Jeollanam-do Province, southern Korea, 27 June , 2013, Seong Yong Moon .

Description. Female. Total body length 2.78 mm. Cephalothorax ( Fig. 3A, B ) is extremely elongated, about 1.46 times as long as the trunk. Head subcylindrical, nearly rectangular, with slightly expanded anterior end. Trunk ( Fig. 3A, B ) buckler-shaped in dorsal view, 1.34 times (1.252 × 0.932 mm) longer than wide with nearly parallel lateral margin and rounded posterior corners. Antennule ( Fig. 3C ) incompletely three-segmented; proximal and second segments armed with a seta (whip) on medioven- tral margin; distal segment with slightly tapering tip with prominent gibbous and apical armature consisting of five setae and three tubercles. Antenna ( Fig. 3D ) biramous, elongate; exopod prominent and longer than endopod, armed with one seta and four prominent claws; endopod one-segmented, armed apically with three spiniform setae. Mandible small, with subapical marginal teeth as Fig. 3E . Maxillule ( Fig. 3F ) biramous, with small endopod and prominent tripartite exopod; endopod composed of short digitiform process surmounted with patch of spinules mediolaterally and a single seta; exopod tripartite with patch of spinules mediolaterally, two large digitiform processes, and a short third one ending with conical elongate setif- erous processes. Maxilla (arrowed in Fig. 3A ) forming arms serving as primary attachment organ; each maxil- lary arm short, tapering and closely opposed to opposite member, but apparently not fused; bulla ovoid. Maxilliped ( Fig. 3G ) subchelate with robust corpus, covered by thick, wrinkled cuticle and a single seta on medial side; long slender subchela with a single seta on ventral margin and a row of teeth at base; large claw (constituting almost one-third of subchela), large auxiliary seta at base of claw medially. Thoracic appendages not observed.

Male. Not found.

Host. Coilia nasus Temminck and Schlegel, 1846

Distribution. Clavellisa chinensis has been found only off Xiamen, China ( Yü, 1933). This is the first record of this species in Korean waters.

Remarks. Genus Clavellisa consists of 12 valid species (WoRMS, 2019), which are associated with clupeiform fish, particularly those from Indian waters ( Kabata, 1979). Clavellisa chinensis was originally reported from off Xiamen, China, and the parasites were reported as Epiclavella chinensis from Gray’s grenadier anchovy, Coilia grayii Richardson, 1845 ( Yü, 1933). This species was previously placed in the genus Clavellisa and like its congeners was parasitic on a clupeiform fish, Co. grayii ( Kabata, 1979) . In this study, after more than 80 years since Cl. chinensis was reported, we successfully rediscovered this species from the Co. nasus . The female is of the usual Clavellisa form. The subcylindrical head is nearly rectangular, the neck cylindrical, and the trunk buckler-shaped, which allowed the Korean specimens to be identified with Cl. chinensis . Clavellisa chinensis was characterized based on the following adult female features: the cephalothorax elongated, the head subcylindrical is nearly rectangular, the trunk buckler-shaped in dorsal view, the antennule is incompletely three-segmented, the exopod of antenna armed with one seta and four prominent claws, the mandible has eight setae, the maxilla with scattered denticles, and the subchelate of maxilliped with robust corpus, covered by thick, wrinkled cuticle and a medial seta. Coilia nasus is distributed in the Northwest Pacific (Yellow Sea, South China Sea, and southwestern Japan) (FishBase, 2019). That is, this species of Clavellisa occurs the Indo-Pacific region mainly ( Kabata, 1979; WoRMS, 2019). However, the testing of this hypothesis awaits more de- tailed knowledge of the host-specificity and zoogeography of species of Clavellisa . Two species, C. dorosomatis Yamaguti, 1939 and C. chinensis , of this genus have been recorded from Korean waters ( Kim, 1998; this study). In this study, I confirmed a new host of C. chinensis , the Japanese grenadier anchovy, Coilia nasus . The new Korean name of “Ung-eo-gin-mok-teol-beol-rae” is proposed for C. chinensis .

Figures

Fig. 3. Clavellisa chinensis (Yü, 1933), adult female.A. habitus, dorsal view. B. habitus, lateral view. C. antennule. D. antenna. E. mandible. F. maxillule. G. maxilliped. Scale bars:A, B=500μm; C, D, G=200μm; E, F=100μm.