Polychaetes (Annelida: Polychaeta) Diversity of Sulu archipelago, Southern Philippines

This study investigates the diversity and morphological distinctiveness of polychaete species across nine coastal municipalities of the Sulu Archipelago, Southern Philippines. Samples were collected through opportunistic sampling from September to November 2023. Taxonomic identification and classification were guided by key reference literature based on diagnostic morphological features, including body segmentation, thoracic and pharyngeal structures, head appendages (antennae, palps, and tentacular cirri), branchial forms, parapodial structures, and chaetal types. A total of 14 species were identified: Perinereis nuntia Lamarck, 1818 (Nereididae), Glycera sp. (Glyceridae), Willeysthenelais sp. (Sigalionidae), Marphysa sp. (Eunicidae), Diopatra sp. (Onuphidae), Eurythoe complanata (Pallas 1766) (Amphinomidae), Notodasus sp. (Capitellidae), Loimia sp. and Thelepus sp. (Terebellidae), and five Sabellidae taxa, the Branchiomma luctuosum (Grube, 1870), Sabellastarte sp. 1, Sabellastarte sp. 2, Acromegalomma sp. 1, and Sabellastarte sp. 2. Notably, all recorded taxa represent new records for the Philippines, while eleven of which are potentially new to science emphasizing the region’s rich yet poorly documented polychaete fauna. These findings increase the number of polychaete species documented from the Sulu Archipelago from 14 to 28 and expand the known polychaete diversity of the Philippines from 275 to 289 species. The substantial increase in documented diversity highlights the Sulu Archipelago as a significant but underexplored center of marine biodiversity and underscores the need for continued taxonomic and biodiversity assessments in the region.