Onchidoris sparsa (Alder & Hancock, 1846)

Onchidoris sparsa

Description: This is a small inconspicuous onchidorid, with a maximum recorded body length of 8mm, but more usually this nudibranch only grows to 5mm. O. sparsa has a pale brown mantle with regularly spaced, darker blotches, which may join up into patches. The mantle bears numerous, small, rounded tubercles. The gills form a horse-shoe shape around the anus.

Habitat: This species feeds on the bryozoans Cellepora pumicosa and Porella concinna and has been found both on shore and in the sublittoral.

Distribution: O. sparsa is possibly commoner on the northern coasts of the British Isles although there are records from Skomer Island, Plymouth and the north coast of Spain. As with several other onchidorids it is rarely recorded.

Similar Species: Careful comparison of the descriptions are necessary to distinguish this species from Onchidoris inconspicua and Onchidoris depressa.

Key Identification Features:

• 8 or 9 rather distant lamellae on the rhinophores.
• A conspicuous pattern of larger tubercles around the bases of the rhinophores.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

WoRMS: Species record : World Register of Marine Species.

iNaturalist: Species account : iNaturalist World Species Observations database