Branchiomma nigromaculatum

About Branchiomma nigromaculatum

Branchiomma nigromaculatum is a marine fan worm in the family Sabellidae. The Atlas retains the historical source spelling Branchiomma nigromaculata as an alias. Its most conspicuous structure is a crown of feather-like radioles at the front of a long segmented body. The body bears dark spots, while the crown can show alternating dark brown, pale, and orange bands. Small finger-like projections called stylodes occur along the radioles; some midlength pairs are longer than their neighbors. Their form, together with microscopic thoracic hooks, helps distinguish this species from similar Branchiomma.

The worm inhabits a tube associated with marine substrate. A published Brazilian study recorded specimens in shallow rhodolith habitat, where calcareous algae provide a complex surface for invertebrates. This supports the reconstruction’s hard-substrate setting without asserting that the Kauaʻi record came from the same habitat. The primary plate shows a longitudinally opened tube to make the whole animal visible. That opening is an anatomical display, not a claim about the worm’s usual behavior. The available references used here do not establish a dependable external male–female contrast or a distinctive juvenile form, so neither is invented.

Kauaʻi evidence is retained from the historical compilation and study material cited on Appendix A, printed page 89. The record documents the source identification under its reported name. It does not establish a current population size, continuous island-wide distribution, or local ecological impact. Similar fan worms have been confused in earlier literature, and the species’ type material was redescribed in 2006. Checking the original Kauaʻi material against that revision would strengthen the identification and clarify which external characters were actually observed.