Diversity and biogeography of scale worms in the subfamily Lepidonotopodinae (Annelida: Polynoidae) from Indian Ocean hydrothermal vents with descriptions of four new species.

This article focuses on the taxonomy, phylogeny, and biogeography of Lepidonotopodinae, a subfamily of scale worms (family Polynoidae) endemic to deep-sea hydrothermal vents, specifically those in the Indian Ocean. Through morphological and molecular analyses of specimens collected from three Indian Ocean ridges—the Southwest Indian Ridge (SWIR), Central Indian Ridge (CIR), and Carlsberg Ridge (CR)—the study describes four new species across two genera, Branchinotogluma and Levensteiniella, increasing the known Indian Ocean Lepidonotopodinae diversity to seven species. Phylogenetic reconstruction confirms the monophyly of Levensteiniella and reveals that the three Indian Ocean Branchinotogluma species belong to distinct clades closely related to species from the East Pacific, West Pacific, and Atlantic, indicating three independent colonization events into Indian Ocean vents. These findings contribute to understanding the biodiversity, distribution, and evolutionary history of vent-associated annelids in the Indian Ocean and highlight the need for further sampling to better assess their diversity.