Branchiae begin on chaetigers 20-28 but starting not always occurs on both sides of the segment at a time.
In some cases the branchiae start branching in a chaetiger much earlier than in the rest of the specimens.
Diagnosis: Branchiae begin on setiger 1 and there are 5 pairs of tentacular cirri on setiger 3.
Branchiae begin from setigers 12 to 15 and there is only a single filament.
The anterior fragment consisted of the head, thorax, and most of the abdomen (about 25 or more pairs of branchiae), while the posterior fragment consisted of the tail, pygidium, and usually about five or fewer branchiate abdominal setigers.
As the tail region increases in setiger number, anterior tail setigers differen tiate into abdominal setigers by forming dorsal ciliary bands and branchiae buds.
McIntosh (1885:282) compared some specimens collected in Sydney, Australia, and others from the Philippine Islands; the former had single-filament branchiae from chaetiger 6, reaching up to 30 filaments in following chaetigers, while the latter had pectinate branchiae from chaetiger 5, and reaching up to 18 filaments.
Branchiae start by chaetiger three, becoming pectinate around chaetiger nine.
Branchiae erected, from chaetiger 10 (11 in some large paratypes); first five pairs (Fig.
is characterized by having 15-16 thoracic chaetigers with four or five rows of uncini and up to three papilliform postchaetal processes on neuropodial lobes, abdominal parapodia bearing flail-tipped neurochaetae and lacking furcated notochaetae, branchiae beginning on chaetiger 10 or 11, interramal cirri, and a low number of subpodial and stomach papillae on anteriormost abdominal chaetigers.
This author indicates that two different branchial arrangements can be found in this species: a) branchiae present at setiger four and continuing for seven segments, and b) branchiae present at setiger three and continuing for 43 segments.
They have eleven thoracic segments with notosetae and neuropodial uncini, two pairs of short branchiae (different from A.