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(Quatrefages, 1866)

Body twisted to right. 3 thoracic chaetigers.
3-5, usually 4, pairs of radioli. Peristomium without eyes.
Non-brooding operculum with an eccentric pin-shaped talon. In breeding specimens the first brood chamber of a series includes this talon: wall around embryos transparent and distal plate either flat or irregularly convex.
The first chaetiger with thin, smooth capillary chaetae and characteristic large, geniculate chaetae with a rounded finely toothed knee; Apomatus-chaetae on third thoracic notopodium, with a similar knee but with a flat ribbed and marginally toothed blade.
Thoracic neuropodia are tori with 10-20 uncini in each. Uncini with 5 longitudinal rows of small teeth.
Abdominal neuropodial chaetae resemble collar chaetae, but the distal part is longer and teeth along the upper margin are larger. Abdominal uncini are like those on thorax (J. pagenstecheri-chaetae).
Dorsal margins of collar not fused to form a tunnel.

Up to 15-19 chaetigers.

Calcareous tube less than 2 mm in diameter, coiled anticlockwise, usually with indistinct longitudinal ridges and a sloping flange (J. pagenstecheri-detail).

Transparent to orange coloured.

On hard substrata and algae, intertidal and sublittoral.

Atlantic, North Sea, Skagerrak, Kattegat, the Belts, Öresund and western Baltic Sea, Pacific, Indian Ocean, Mediterranean, Adriatic, Black Sea.

Janua pagenstecheri