Scale worm diversity in abyssal and hadal environments (Aphroditiformia, Annelida)

The deep sea is dominated by diverse invertebrate communities, of which annelids are among the most prolific. Within such annelids, scale worms (Aphroditiformia) have long been recognized as a major component to the composition of deep-sea communities, yet their overall diversity and distribution is unknown. To better understand this diversity, we provide the first comprehensive census of scale worms inhabiting depths at or below 3000 m. Our literature analyses across all species recognized by the World Register of Marine Species (WoRMS) revealed 418 records and 122 species spread across Aphroditidae, Polynoidae and Sigalionidae, of which the second was the most species rich. Within Polynoidae, 12 species were identified as hadal zone exclusives. Caveats of the dataset are discussed. Historical, recently published, and new in situ observations of Aphroditiformia at hadal depths are also presented. These results provide a baseline for future investigations across deep sea Aphroditiformia.