Chaetozone Malmgren, 1867
Chaetozone sp. 8
Voucher specimens. SEALION: stations 3MFB and 17MFB.
Diagnosis. Reaching relatively large size, with voucher specimen (3MFB) 14.7mm in length with 142 chaetigers. Body slightly dorso-ventrally flattened, gradually widening in thoracic chaetigers, distal abdominal chaetigers concertina-like with prominent edge to chaetiger; ventral groove present from anterior thoracic chaetigers down body. Body not pigmented.
Prostomium and peristomium distinct and separated from thoracic region. Eyes absent. Prostomium, short, conical and pointed with a rounded tip. Peristomium, short, as wide as long, domed or with crest over peristomium; with three compressed annulations, difficult to see, particularly dorsally. Dorsal tentacles situated in junction between peristomium and thorax, dorsally situated on the third annulation and proximal to first branchiae. Branchiae situated dorsal to notochaetae found in thoracic chaetigers, less obvious in anterior abdominal chaetigers.
Chaetae comprise capillaries in anterior chaetae, with long thickened spines occurring in abdominal region of the body, from approximately chaetiger 79 (in voucher 17MFB). Thoracic notochaetae up to 3–5 chaetigers in length; 7 to 9 capillaries per fascicle; neurochaetae shorter with 9 to 11 capillaries per fascicle. Abdominal chaetigers with mixture of simple capillaries and thickened spines carried on low ridges, fascicles separated dorsally and ventrally, notopodial with two dorsal capillaries and three long pointed spines, while neuropodia with 6 or more elongated thin spines.
Pygidium is a rounded plate-like disk.
MSGP. Specimens heavily stain, prostomium and peristomium stain with only a narrow band of light or no stain between; body with obvious bands both dorsally, laterally and ventrally on the edge of the chaetigers.
Remarks. This species is easily recognised by its distinctive body shape with the appearance of distinct pro- and peristomium, the MGSP, and the arrangement of the abdominal parapodia and chaetae. The shape of the body resembles C. bathyala (Blake, 2015) but differs in lacking the ventral ridge observed in Blake’s species, the form and fascicular arrangement of the spines and the peristomial region is more elongate in C. bathyala. The presence of a dome or crest over the peristomium is shared with C. setosa Malmgren, 1867; C. corona Berkeley and Berkeley, 1941; C. platycera Hutchings and Murray, 1984 and C. pugettensis Blake, 2015. The FI specimen can be distinguished from all these species by its characteristic MGSP, for example C. pugettensis a staining pattern is absent while dorsal staining in the thoracic chaetigers of the FI species is not as prominent in C. setosa.
