Notaulax phaeotaenia

About Notaulax phaeotaenia

Notaulax phaeotaenia is a sabellid fan worm whose conspicuous feeding crown sits on an elongated basal support above a slender segmented body. The older name Hypsicomus phaeotaenia appears in the Kauaʻi harbor and nearby reef compilation, Appendix A, printed page 89, of Bishop Museum Technical Report 29a. Its inclusion records the identification used in that source; it does not establish present abundance, persistence at every station, or a resolved native or introduced origin.

Fauvel’s 1953 treatment, under Hypsicomus, describes specimens about 40–60 mm long with a low collar and a membranous, transparent tube. The radioles bear simple eye spots in paired longitudinal arrangements rather than the large compound eye structures seen in some other fan worms. Fine featherlike branches provide the crown’s filtering surface. The first chaetiger has chaetae in an oblique, somewhat curved row; the thorax and abdomen carry different combinations of capillary chaetae, broadened chaetae and hooks. These small structures require microscopy and are more useful for identification than an attractive crown alone.

The plate follows the complete original silhouette reproduced by Fauvel after Schmarda, with its long crown base, narrow abdomen and complete tapering posterior end. Alternating red and yellow crown bands are grounded in Schmarda’s illustrated concept, as compared with the uniformly red, shorter-based crown of Notaulax tilosaula in the 2010 taxonomic review. The soft tube is opened longitudinally to reveal the entire animal as an anatomical reconstruction. That presentation is not a claim that the worm normally exposes its body on rubble. No externally distinct male, female or juvenile is invented.

The genus changed following Perkins’s 1984 revision. Modern work places these former Hypsicomus species in Notaulax, while emphasizing that old coral-boring records under phaeotaenia can represent other Notaulax species. A 2020 review explicitly calls for corroboration of this taxon’s supposed worldwide distribution. Consequently, reports of boring behavior, exceptionally wide geographic range or particular ecology from another named Notaulax are not transferred to the Kauaʻi entry. Suspension feeding through the crown is supported at the sabellid family level. A fresh Kauaʻi voucher comparison should examine the crown base, collar, radiolar eyes and chaetae against the relevant species concepts. The historical occurrence remains visible while those taxonomic and ecological boundaries remain explicit.