Symbiotic ecology of polychaete species in the family Spionidae (Annelida)

Abstract

The family Spionidae Grube, 1850, one of the most abundant polychaete groups in Annelida in terms of species numbers and biomass, is globally found in a wide variety of marine environments. Among this family, members belonging to the Polydora-complex (or referred to as polydorids, Tribe Polydorini, or polydorins) are well known for their ability to bore into various hard calcareous substrates. This group comprises boring and non-boring species, both of which include symbiotic species and therefore utilize a variety of substrates, including other invertebrate species, as habitat. In the course of research on spionid polychaetes in Japan, the author recently discovered and described two new species, Polydora lingulicola Abe & Sato-Okoshi, 2020 and Polydora tunicola Abe, Hoshino & Yamada in Abe, Hoshino, Yamada, Ogino, Kawaida & Sato-Okoshi, 2022, that show novel and unusual obligate symbiotic relationships with lingulid brachiopods and ascidians, respectively. Here I review the known symbiotic relationships in spionid polychaetes, including above two newly discovered symbiotic relationships.