Body of this scale-worm long of uniform width. Dorsal and ventral surfaces smooth.
On the dorsal surface there is a tubercle in the mid-line of each segment in the anterior region, from the 32nd segment the mid-line tubercle and the 2 dorsal tubercles form 3 prominent rows along the length of the body.
Prostomium bilobed, usually with a small rounded peak on each lobe, and median and lateral antennae, papillate or smooth, and a pair of palps. Two pairs of eyes, the anterior pair near the front of the prostomium, the posterior pair in front of the rear margin.
First segment bearing chaetae and a pair of dorsal and ventral tentacular cirri. A rounded facial tubercle present.
Scales overlap but do not cover the dorsal surface of the body. They occur on the anterior region only, on segments 1, 3, 4 and 6, then alternately to the 22nd and then on segments 25, 28 and 31. Scales are rounded, the margins are smooth or have a few very small cylindrical papillae and the surfaces have small round tubercles (P. scolopendrina-detail).
Notopodia are small mounds with a ventral acicular ligule and several chaetae. Notopodial chaetae with rows of spines and blunt cleft tips. Neuropodia well developed with an anterodorsal finger-shaped and a posterior rounded ligule. Neuropodial chaetae of 2 kinds: 1) upper 1 or 2 stout chaetae, wide with small spines and blunt tips, not present on all segments; 2) with rows of spines on the terminal part with bidentate tips (P. scolopendrina-parapodium).
Up to 120 mm for 100 chaetigers.
Dark red on the dorsal surface, yellow to reddish brown on the ventral surface. A dark pigmented streak is usually visible across the dorsal surface of each segment in the anterior region giving a striped appearance.
Littoral to 60 m, often found in terebellid polychaete tubes.
Atlantic between Iceland and South Africa, Mediterranean, Adriatic, Black Sea, English Channel, northern North Sea up to Swedish Skagerrak coast.