Anchialine caves have revealed a variety of highly adapted animals including several records of nerillid annelids. However, only one stygobitic lineage, Speleonerilla nom. nov. (previously known as Longipalpa), seems obligate to this environment. We here provide new information on this lineage including the description of three new species, two new records, and the first phylogeny of the genus. All species have been collected from the water column of anchialine caves in the Caribbean, Bermuda, and Canary Islands, contrary to their benthic and interstitial nerillid relatives. New species were described combining light, scanning electron, and confocal laser scanning microscopy and named after traditional dances from their corresponding countries. Speleonerilla isa sp. n. is morphologically the most divergent species, characterized by the presence of nine segments, two pairs of spermioducts, and parapodial cirri present on all segments. Speleonerilla calypso sp. n. and S. salsa sp. n. are mainly distinguished from S. saltatrix by the presence of one additional pair of nephridia and are diagnosed based on unique combinations of characters including the specific arrangements of trunk ciliation, parapodial cirri, and number of chaetae. Two additional records from anchialine caves in Northeast Cuba and México were not described due to limited available material. Phylogenetic analyses of four molecular markers recovered the East Atlantic S. isa as sister to a clade containing the West Atlantic species, the interrelationship of which did not further reflect the geographical distances within the Caribbean. Evolutionary adaptations are discussed, such as the long ciliated palps and pygidial lobes of Speleonerilla used for swimming and their high tolerance to changing salinities when apparently feeding on bacteria in the halocline of the anchialine cave systems.