Description: This isopod has a very long body, especially the middle section which is particularly long and has angled corners. The first 4 legs are long and sparsely covered in long, setae (hairs). They are directed towards the mouth of the animal and used for feeding. The next sets of legs are shorter and adapted to hold on securely. There are many conspicuous large tubercles on the body, and there are 3 conical tubercles on the head. This species can grow to around 10 mm. They have very long antennae and conspicuous eyes. The outer edges of the pleotelson are deeply serrated.

Habitat: Most often seen subtidally, usually clinging to hydroids, but may sometimes be encountered intertidally.

Distribution: Recorded from all around Britain and Ireland, but rare. Most records are from south-west coast.

Similar Species: Quite a distinctive species, could be potentially confused with Astacilla longicornis but closer inspection should make distinguishing easy.

Key Identification Features:

• Isopod with very long body and especially long midsection, with angled corners.
• First 4 legs are long and sparsely covered with setae.
• Very long antennae.
• Many conspicuous, large tubercles on body.
• Outer edges of pleotelson deeply serrated.

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

iNaturalist: Astacilla damnoniensis at iNaturalist World Species Observations database.

GBIF data for Astacilla damnoniensis

WoRMS: Astacilla damnoniensis at World Register of Marine Species. Accepted name: Astacilla damnoniensis (Stebbing, 1874). AphiaID: 335294.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Malacostraca; Eumalacostraca; Peracarida; Isopoda; Valvifera; Arcturidae; Astacilla