Brooding deep-water onuphid polychaetes (Annelida) from the Bay of Biscay

We report on three species of deep-water onuphid polychaetes (Nothria maremontana, Paradiopatra hispanica and Rhamphobrachium brevibrachiatum) from the Bay of Biscay from depths of 468 to 1186 m. The three species contained eggs and/or juveniles inside the parental tubes and R. brevibrachiatum had a cocoon-like capsule attached on the outside of its tube containing fibres and sperm. We present brief taxonomic descriptions of the three species, including some observations on ontogenetic chaetal changes in N. maremontana. The brooded eggs ranged from 300 to 340 μm in diameter in N. maremontana, while R. brevibrachiatum eggs ranged from 390 to 450 μm; juveniles consisted of 6 chaetigers for N. maremontana and 6-45 chaetigers for P. hispanica. We describe and illustrate the eggs, juveniles and sperm capsule. Although the origin of the sperm capsule is questionable, we reject the possibility of an unrelated passenger and speculate that the structures contained inside the capsule are long, thin spermatophores of a type not previously known for onuphids.