Autolytus brachycephalus

(Marenzeller, 1874)

Description:
Prostomium rounded with four eyes with lenses, in a trapezoid arrangement, with two ocelli. Palps hardly visible dorsally, with a median groove. Median antenna a little longer than lateral ones. Lateral antennae a little more than 2x as long as prostomium.
Dorsal tentacular cirri about as long as lateral antennae, ventral much shorter. Dorsal cirri of first segment, longest, longer than median antenna. All other dorsal cirri much shorter, regularly alternating shorter or longer, longest not much longer than segment width. Two aciculae present. Blades of compound chaetae bidentate, secondary tooth larger than terminal tooth. Pharynx S-shaped. Trepan with 21-31 teeth, of which 8-13 are large; the others a little smaller.

Size:
Body up to 15 mm long for 88 segments.

Colour:
Transparent to reddish-yellow, segments with 2 rows of shining, pointed glands. Dorsal cirrophores with red figure 8. Tips of anterior appendages reddish. Pharynx and stomach pink to red-purple.

Habitat:
0-120 m depth.

Distribution:
Eastern North Atlantic, English Channel, southern North Sea, Skagerrak.

Remark:
Hamond (1969) thought it "probable that in Norfolk waters both the intertidal and the offshore Autolytus of the brachycephalus-prolifer-edwardsi complex form a single, very variable but reproductively homogenous, population".

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