Yusuke Nishida
Graduate School of Integrated Sciences for Life, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Panakkool Thamban Aneesh
Graduate School of Integrated Sciences for Life, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Fisheries Laboratory, Blue Innovation Division, Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Universiti Sultan Zainal Abidin, Gong Badak Campus, 21300 Kuala Terengganu, Terengganu, Malaysia
Yusuke Kondo
Fisheries Laboratory, Blue Innovation Division, Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Ione Madinabeitia
Graduate School of Biosphere Science, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan (formerly)
Hirofumi Yamashita
Ehime Prefecture Aquaculture Research Group Promotion Office of Agriculture, Forestry and Fisheries Research Institute, Fisheries Research Center, Uwajima, Ehime 798-0104, Japan
Sho Shirakashi
Aquaculture Research Institute, Kindai University, 3153 Shirahama, Nishimuro, Wakayama, 649-2211, Japan
Kazuo Ogawa
Meguro Parasititological Museum, 4-1-1 Shimomeguro, Meguro-ku, Tokyo 153-0064, Japan
Kaori Wakabayashi
Graduate School of Integrated Sciences for Life, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Kenta Adachi
Graduate School of Integrated Sciences for Life, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Japan Fisheries Research and Education Agency, Fisheries Technology Institute, Kamiura, Saeki, Oita, 879-2602, Japan
Susumu Ohtsuka
Graduate School of Integrated Sciences for Life, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Fisheries Laboratory, Blue Innovation Division, Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, 5–8–1 Minato-machi, Takehara, Hiroshima, 725–0024, Japan
Universiti Sultan Zainal Abidin, Gong Badak Campus, 21300 Kuala Terengganu, Terengganu, Malaysia
Communicated by Benny Kwok Kan Chan
The present study describes and illustrates the morphology of naupliar and copepodid stages of Caligus sclerotinosus Roubal, Armitage and Rohde, 1983 (Copepoda: Siphonostomatoida: Caligoida), an invasive, non-indigenous parasite collected from commercially important red sea bream Pagrus major (Temminck and Schlegel, 1843) (Sparidae) cultured as well as wild populations in western Japan. The life cycle of C. sclerotinosus consists of 8 stages: two nauplii, five copepodids (copepodid I to V) and one adult, which exhibited the general pattern of other congeners. Sexual dimorphism was first observed in the urosome and antenna of copepodid IV. The body lengths of the developmental stages of 14 Caligus spp. are compared to those of C. sclerotinosus. The oral cone of copepodid I is highly unique for its sucker-like shape, widely expanded terminally. All post-naupliar stages were found on the same host fish P. major, rejecting the previous hypothesis for the presence of intermediate hosts for the development of C. sclerotinosus.
