Description: This ascidian forms transparent gelatinous colonies on algae. The small zooids are scattered densely throughout the sheet. Each zooid has a small inhalant pore and there are a few larger exhalant openings, but these openings are not conspicuously pigmented. There is a pattern of small yellow pigment bodies in the surface layer which can be seen on close inspection. 4mm thick x 50mm wide sheets.

Habitat: A common ascidian in a wide variety of habitats in shallow water.

Distribution: Widespread around the British Isles.

Similar Species: Diplosoma spongiforme has been much mistaken for this species in the past. It forms much larger, more heavily pigmented, sheets on hard substrata. Diplosoma singulare forms similar smaller transparent colonies on seaweeds but has not been reported yet from the British Isles.

Key Identification Features:

• Transparent gelatinous sheets on algae.
• Pattern of tiny pigment bodies in surface.
• Zooids colourless, scattered.

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

iNaturalist: Diplosoma listerianum at iNaturalist World Species Observations database.

WoRMS: Diplosoma listerianum at World Register of Marine Species. Accepted name: Diplosoma listerianum (Milne Edwards, 1841). AphiaID: 103579.

Classification: Biota; Animalia; Chordata; Tunicata; Ascidiacea; Aplousobranchia; Didemnidae; Diplosoma