Chaetozone Malmgren, 1867
Chaetozone sp. 1
Voucher specimens INFLEXIBLE: station 2MFA; ENDEAVOUR: station E4FA.
Diagnosis. Complete specimens 8.3mm long with 34 chaetigers. Body inflated anteriorly, widest at junction of thoracic and abdominal chaetigers; anterior abdominal chaetigers rounded becoming slightly dorso-ventrally flattened segments. Ventral groove in posterior thoracic region (may be a fold due to inflated body). Pygidium with large rounded ventral lobe.
Prostomium rounded, blunt. Peristomium as long as wide or slightly longer than wide, with three annulations. Dorsal tentacle situated on a narrow achaetigerous segment immediately distal to peristomium; first branchiae situated on same achaetigerous segment but ventral to dorsal tentacle. Branchiae situated above notochaetae.
Thoracic chaetae all capillaries; emerging from low mounds, short approximately 2 to 3 chaetigers in length, 4 to 6 chaetae in each fascicule in thoracic region. Acicular spines starting about one third to half way down the body; not forming cinctures in distal chaetigers, fascicules are separated; 3 to 4 long spines per fascicule with one to two thin capillaries in proximal abdominal chaetigers, but distal chaetigers without capillaries.
MGSP. Faint bands on prostomium and peristomium, diffuse staining on body.
Remarks. This is a distinctively shaped species, in particular the blunt shape of the prostomium and the inflated body are not often found in Chaetozone. However, the form and arrangement of the dorsal tentacles and first branchiae on an achetigerous segment is commonly found in the genus as are the acicular spines in abdominal chaetigers. The shape of the body and prostomium separate this species from the others in the FI samples.
Chaetozone sp. 1 resembles Chaetozone pinguis Hartman, 1978 in the shape of the body and rounded prostomium. However C. sp. 1 does not have the acicular spines starting in the thoracic chaetigers as Hartman records for C. pinguis nor is the arrangement of dorsal tentacle and first branchiae the same.
