石斑鱼鱼虱病的研究──Ⅰ.南海鱼虱,新种Caligus nanhaiensis n.sp.

A STUDY ON LICE DISEASE IN CULTURED GROUPER EPINEPHELUS SP─Ⅰ.DESCRIPTION ON THE PATHOGEN CALIGUS NANHAIENSIS N.SP.

记述华南地区网箱养殖石斑鱼鱼虱病病原──南海鱼虱，新种Caligusnanhaiensisnsp．形态的光镜和电镜观察结果，并对南海鱼虱与相似种C．seriolaeYamaguti，1936和C.tanagoYamaguti，1939的形态特征进行详细比较。

The lice disease is one of the dangerous fish diseases which is prevalentin marine cultured fish in the South China Sea. This disease is caused by parasiticcopepoda, Caligus nanhaiensis n. sp. In this paper, the pathogei's morphology is described in detail.Host: Epinephelus awoara, E akaaraHabitat in host: gill;Collected from: Daya Bay, Shenzhen;Holotype and paratypes: One female holotype and 20 paratypes (12 female, 8male) are deposited in South China Sea Institute of Oceanology of the Chinese Academy of Sciences. The registered number of the holotype is YS931001, and the registered number of the paratypes is YS931002.The characteristics of Caligus nanhaiensis n. sp. are as following:The female of this parasite is 2.56 (2.41－2.73) mm in body length. Carapacenearly rounded, convex at anterior end, truncate at posterior end. Frontal plate welldefined, with prominent lunules. The lunules disc－like, 0.08mm in diameter. Thefourth thoracic segment broaded but short, 0.1mm x 0.2mm. The genital segment nearly rounded, curved at anterior end and truncate at posterior end. The developedgenital segment 0.65mm x 0.75mm. Abdomen cylindrical, distinctly 2－segmented. Thefirst segment 0.299mm x0.264mm; the second one 0.17mm x0.17mm. Cadaul rami0.1mmx0.08mm, with hairs on inner margin and 3 terminal setaes on top as well asanother setae and a spine on posterior comer of its outside lateral. The first antennashort, its terminal segment with 9 setaes at tip. Basic segment of the second antennabroaded, 2 spines at its posterior corner. Furca quadrangular, its basic part equaledto its branches. The branch curved to inner side, blunt at terminal. The basic hookon the exopod of the third leg reached the middle of the third segment, with hairs onmargin. The sixth leg with one setae.The male is smaller than the female, body length 1.75(1.63－1.80)mm. The genitalsegment 0.36mm x 0.27mm. Abdomen 2－segmented, the first segment0.07mm x 0.2mm, the second one 0.2mm x0.17mm. The second antenna 0.11mm inlength, 0.55mm in width, the tip of its terminal segment developed into divergentclaws. The fifth leg with 4 setaes. The sixth leg with 2 setaes.Remarks: This species resembles Caligus seriolae Yamaguti, 1936 and C.tanago Yamaguti, 1939, very closely in general anatomy, but differs in body size,body morphology, number of setae on the first antenna, and the morphology ofmandible.