Abyssoninoe abyssorum (McIntosh, 1885)
Voucher specimen: SEALION: station 1MFC and 8MFA; TOROA: station T5FB; INFLEXIBLE: station 2MFA.
Diagnosis. Specimens fragmented, Sealion 1MFC specimen ~30mm in length with 175 chaetigers. Prostomium short, pointed. Two achaetigerous segments. Postchaetal lobes conical, short.
Maxillary carriers constricted about a quarter way down, pointed and pips separated; Max I large arched without supplementary teeth, Max II with three to four large teeth; Max III small semi-triangular with small tooth at apex near junction with Max IV. Max V and VI fused forming a broad rectangular plate, small tooth emerges from inner border of the plate.
Chaetae comprise of hooded hooks, limbate capillaries, and yellow aciculae. The hooded hooks arise from chaetiger 1 or slightly further back, initial chaetae resemble limbates but have small teeth/hooks developing at the tip. Hooded hooks become distinct in distal anterior chaetigers, characterised by main fang with approximately four or more secondary teeth.
Remarks. The key features of this species as pointed out by Orensanz (1990) are the very delicate hooded hooks in the anterior chaetigers which can only be distinguished by examination with a high powered microscope and by the fusion of Max IV and V. This species has a wide geographic and bathymetric distribution, being recorded from around the Southern Ocean, off New Zealand and Chile, with a depth range of upper bathyal to 6000 m.
