Species description: A small, errant polychaete that reaches up to 31 mm in length. This worm can have up to 135 chaetigers, of which 26-30 anterior chaetigers are uniramous. The proboscis has two distinct types of papillae, which are arranged in rows. There may be some pigmentation in larger specimens, but in smaller specimens this seems to be faint or completely absent. On the back there are patches of brown spots in the front section of the body, followed by 2-3 bands of dark pigment around the middle, which fade towards the rear of the animal. There may be two large dark spots in the middle section also, but these are not always present. All parapodia have a dark band.

Habitat: Coarse sediment or shelly gravel.

Distribution: Scattered records from all around Britain and Northern Ireland, possibly under-recorded. Very few records on public databases for Ireland.

Similar Species: Could be confused with a number of other errant polychaetes, specialist identification or microscopic examination alongside a more detailed key may be required.

Key Identification Features:

• Errant polychaete around 31 mm in length.
• 135 chaetigers, 26-30 anterior chaetigers uniramous.
• Two types of papillae arranged in rows.
• Older/larger individuals may have distinctive patterning.

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

iNaturalist: Goniadella gracilis at iNaturalist World Species Observations database.

WoRMS: Goniadella gracilis at World Register of Marine Species. Accepted name: Goniadella gracilis (Verrill, 1873). AphiaID: 130145.

Classification: Biota; Animalia; Annelida; Polychaeta; Errantia; Phyllodocida; Glyceriformia; Goniadidae; Goniadella