Body broad and flattened, posteriorly tapered.
Prostomium heartshaped to triangular. Median antenna situated slightly in front of eyes, as long as paired ones. Eyes large, rounded. Proboscis very long and thin, densely covered with rounded papillae. Terminal ring of about 16-18 papillae.
Segment 1 not visible dorsally. Tentacular cirri of segment 1 reaching about segment 4. Dorsal tentacular cirri of segments 2 and 3 reaching about segment 9. Ventral tentacular cirri slightly flattened, reaching about segments 4-5. Chaetae present from segment 2. Dorsal cirri of median segments heartshaped, about as long as wide. Parapodial lobes acutely bilobed with pointed tips, upper one slightly larger than lower, with a large number of chaetae. Terminal end of chaetal shaft with teeth decreasing in size proximally. Blades slender. Ventral cirri broad, more or less distinctly pointed.
Pygidial cirri slightly flattened, about 3-5 times as long as wide. Minute median pygidial papilla present (P. punctifera-detail).
Up to 250 mm for 270 segments.
Living animals yellowish brown to orange. Four dark pigment spots in a transverse line across anterior prostomium just anterior to median antenna, lateral spots often less distinct. Spots also in middle of tentacular cirri and dorsally on the segments, initally four on each segment, later six. Segment 2 without spots. Dorsal cirri with spots in centre and occasionally with additional smaller, irregularly distributed ones. Spots also near base of ventral cirri and on ventrum, much less regular than on dorsum. Eyes brown. Mature females light green, males yellowish. Preserved animals darker. Pigmentation pattern preserves well. Eyes brownish black.
Intertidal and subtidal among kelp holdfasts, in crevices among stones and on shell gravel.
North Atlantic, Mediterranean, Adriatic, English Channel, Southern North Sea.