New record of bioluminescence in Odontosyllis cf. australiensis (Annelida: Syllidae: Eusyllinae) in Japan

Abstract

AbstractBioluminescence is widespread in the marine environment. The bioluminescence of some species of the fireworm Odontosyllis (Annelida: Syllidae: Eusyllinae) has been well studied, although the presence or absence of bioluminescence in most species of this genus is yet to be revealed. The bioluminescent worms were observed after sunset around the new moon day in July and October 2020 and in July to October 2021 in Nagasaki Prefecture, Japan. Molecular phylogenetic analysis based on two mitochondrial and one nuclear gene sequence showed that the worms were closely related to Odontosyllis australiensis, but the partial 16S rRNA gene sequences differed by 2% between those of the Japanese and Australian material. Because only epitokes, i.e. morphologically modified sexually mature worms, were collected, further studies on morphological characters of atokes would be required in the future. We therefore tentatively refer to them as Odontosyllis cf. australiensis. Molecular phylogenetic analysis also showed that known bioluminescent Odontosyllis species belong to various lineages.