Description: This scale worm reaches around 35 mm in length, with a body made up of 38 segments. There are 15 pairs of elytra and each has a small fringe of short hairs around part of the outer edge. The elytra have some small tubercles on the surface with large, rounded tubercles towards the bottom of each scale, one taking the form of a mace. Tubercles are all isolated, rather than grouped.

Habitat: Found from the lower shore down to 200 m.

Distribution: Scattered records from most coasts of Britain and Ireland.

Similar Species: There are many other species of scale worm present in Britain and Ireland which may need microscopic examination for a species level identification. Some species can be identified in the field with appropriate expertise and experience.

Key Identification Features:

• Some small tubercles on surface of scales.
• Mace-shaped larger tubercles towards bottom outer edge of each scale.

Distribution Map from NBN: Harmothoe clavigera at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Harmothoe clavigera at iNaturalist World Species Observations database.

GBIF data for Harmothoe clavigera

WoRMS: Harmothoe clavigera at World Register of Marine Species. Accepted name: Harmothoe clavigera (M. Sars, 1863). AphiaID: 130760.

Classification: Biota; Animalia; Annelida; Polychaeta; Errantia; Phyllodocida; Aphroditiformia; Polynoidae; Polynoinae; Harmothoe