Rissoa lilacina

R├ęcluz, 1843

Description (shell):
Shell solid, oval-conical, with six or seven slightly tumid whorls, the youngest two or three costate. Ribbing is incomplete on third whorl and apertural view of shell will show costae on last and penultimate whorls only; apart from a wide varix, costae are slight or absent on adapertural part of last whorl, and here a fine reticulate pattern is most prominent. On costate areas of shell reticulation is confined to troughs between costae. On some shells ribbing is slight, requiring careful examination of shell; var. ecostata has neither costae nor reticulations (R. lilacina).

Up to 5 x 2.8 mm.

Shell whitish with longitudinal orange-brown stripes which, on costate whorls, lie between costae; apex and peristome with lilac tinge.

Body as in Rissoa parva ; cephalic tentacles with bright yellow stripe dorsally.

Occasional or locally common on weeds and amongst sandy gravel from LWST down to 50 m.

A southern species extending to the western Channel basin, the Welsh coast, western shores of Scotland, and the south and west coasts of Ireland; absent in the southern North Sea (Distr. R. lilacina).