An accompanying isopod, Alitropus typus (Aegidae) introduced to Tokyo Sea Life Park, Japan on the nurseryfish

Abstract

A female specimen of Alitropus typus H. Milne Edwards, 1840 (Isopoda: Aegidae), a micropredator of fresh- and brackishwater fishes, was found from nurseryfish, Kurtus gulliveri Castelnau, 1878 (Kurtiformes: Kurtidae) at the Tokyo Sea Life Park, Japan. The isopod crawled out from the fish, representing the first time that the micropredator, A. typus, has been discovered in Japan. The present paper provides a description of the morphological characters of the isopod, and molecular barcod for identification. The morphological characters of the specimen are in well agreement with the original and the previous descriptions of A. typus. The molecular analysis, A. typus formed an independent clade in the maximum likelihood trees of Aegidae based on cytochrome c oxidase subunit I (COI) gene. However, K2P distance of the partial COI gene sequences determined from the present specimen is 17.85% from that of A. typus present in the GenBank. This isopod is an introduced species imported from north Australia that attaches to the nurseryfish. However, great care is taken to ensure that these animals imported from overseas do not come into contact with Japan’s natural environment.