<i>Nerocila phaiopleura</i>, a cymothoid isopod parasitic on Pacific bluefin tuna, <i>Thunnus orientalis</i>, cultured in Japan

Abstract

Abstract. Ovigerous females of Nerocila phaiopleura Bleeker, 1857 were collected from the body surface of young Pacific bluefin tuna, Thunnus orientalis (Temminck & Schlegel, 1844), cultured in Japan. This represents the first record of N. phaiopleura in finfish mariculture. The species is the third cymothoid isopod from maricultured fishes in Japan. The infected fish had a large hemorrhagic wound caused by N. phaiopleura at the attachment site. Thunnus orientalis is a new host of the isopod. No cymothoid infection has so far been reported from wild individuals of T. orientalis that swims at high speeds in the oceans, and the observed occurrence of N. phaiopleura on this fish species is regarded as unusual under confined mariculture conditions. The hosts and geographical distribution records of N. phaiopleura in Japan are reviewed.

Three new host records for the marine fish ectoparasite, <i>Nerocila phaiopleura</i> (Isopoda: Cymothoidae), with a list of its known hosts

“…Isopods were all found to be attached to the posterior body surface of these fishes. The specimens of N. phaiopleura collected are identical with those of N. phaiopleura described by Bowman & Tareen (1983), Bruce (1987), and Nagasawa & Shirakashi (2017), measuring 21.1-22.8 (mean 21.8) mm in total length (with uropod rami) and 8.0-10.0 (9.0) mm in maximum width (n 3). Voucher specimens of isopods are deposited in the Crustacea (Cr) collection of the National Museum of Nature and Science, Tsukuba, Ibaraki Prefecture, Japan (NSMT-Cr 25572-25573).…”

“…The three species, viz., S. japonica, T. japonicus, and E. micropus, which were found to harbor N. phaiopleura in this study, are added herein as its new hosts. In Japan, in addition to these three newly added species, the following seven species have been reported before as the hosts: dotted gizzard shad, Konosirus punctatus (Temminck & Schlegel, 1846); Japanese sardinella, Sardinella zunasi (Bleeker, 1854) Bruce (1987) Crustacean Research 46 view of Japanese cymothoids by Yamauchi (2016), while the remaining three species were reported by the senior author (KN) and colleagues (Nagasawa & Tensha, 2016;Nagasawa & Shirakashi, 2017;Nagasawa & Nakao, 2017). Hata et al (2017) phaiopleura utilizes a wide variety of fish species as its hosts but prefers the fishes of this order, especially those of the first two families.…”

“…Nerocila phaiopleura Bleeker, 1857 is a skin parasite of actinopterygian fishes in the IndoWest Pacific (e.g., Bruce, 1982Bruce, , 1987Bowman & Tareen, 1983;Bruce & Harrison-Nelson, 1988;Trilles et al, 2011Trilles et al, , 2013Aneesh et al, 2013;Nagasawa & Shirakashi, 2017). During a study of cymothoid infection of fishes in coastal waters of the northwest Pacific Ocean off Mie Prefecture, central Japan, we collected N. phaiopleura from three fish species, which represent new host records for the isopod.…”

New Record of a Marine Fish Parasite <i>Nerocila trichiura</i> (Crustacea: Isopoda: Cymothoidae) from Japan, with its Confirmed Distribution in the Western North Pacific Ocean

“…The observed disease conditions were most probably induced by the skin feeding and deep insertion of the pereopod's dactyli of the species. Similar skin wounds are also found on marine fishes infested by N. phaiopleura in Japanese waters (Nagasawa and Tensha 2016;Nagasawa and Shirakashi 2017;Nagasawa and Isozaki 2017;Nagasawa and Kawai 2018).…”

“…The body surface-attaching cymothoid genus Nerocila Leach, 1818 currently comprise 43 valid species (Trilles 1975;Bruce 1987;Bokyo et al 2019). Little information is available on the cymothoids of the genus infesting Japanese fishes, and only two nominal species have been reported from Japan to date (Yamauchi 2016): Nerocila japonica Schioedte and Meinert, 1881 from 17 species of wild fishes in 10 families (Cyprinidae, Mugillidae, Latidae, Lateolabracidae, Sparidae, Embiotocidae, Terapontidae, Labridae, Gobiidae, Monacanthidae) from central and western Japan and from one species of farmed fish (Kyphosidae) from central Japan (Yamauchi and Nagasawa 2012;Nagasawa and Kawai, 2019); and Nerocila phaiopleura Bleeker, 1857 from eight species of wild fishes in six families (Clupeidae, Dussumieriidae, Engraulidae, Carangidae, Scombridae, Sphyraenidae) from central and western Japan and from one species of farmed fish (Scombridae) from central Japan (Mitani 1982;Bruce and Harrison-Nelson 1988;Nagasawa and Tensha 2016;Nagasawa and Shirakashi 2017;Nagasawa and Isozaki 2017;Nagasawa and Nakao 2017;Nagasawa and Kawai 2018).…”