Rissoa guerinii Récluz, 1843
British isles to Canarias, to Mediterranean.
Grazer and detritus feeder in the infralittoral-circalittoral.
 
Shell turriculated, solid, composed of about 8 whorls, the upper ones smooth and tapering, the following ones sculptured in their lower half by longitudinal oblique costae, weak below the suture, and markedly protruding above it, giving the spire the appearance of a melting ice-cream. Spiral sculpture made up of thin striae, obsolete when crossing the radial costae, slightly more pronounced between them. On the last whorl, the costae slowly end at the periphery; below the latter, only remains the spiral sculpture. Colours: background and radial costae whitish to purplish; interspaces and lower half of the last whorl adorned by longitudinal undulating bands of small dark transverse lines; this pattern draws some zig-zags on the base; apex creamy to purplish. Aperture smooth; lips violet; external margin varicose; this varix whitish.

12m deep, Scilla, Messina Strait, Italy. 3,5mm.
8m deep, a the edge of a Posidonia meadow, Tenda Bay, NW. of Itanos, north of Palaikastro, east of Sitia, NE. Crete. 3,5mm.
Synonyms: costulata, subcostulata.
The pattern described supra may exhibit some variations: it can be visible also on the radial costae, or completely absent in some extreme eco(pheno)types, as it can be seen infra.
8m deep, Amtlla de Mar, Sant Jordi d’Alfama, Catalunya, NE. Spain. 5mm.
8-12m deep, in grit among Posidonia meadows, Punta di Parata, Corbara, NW. Corsica. 4,2mm.
5m deep, Split area, S. Croatia. 6mm.
Original pictures provided by N. Lete (HR) – (CC BY-NC-SA).
Infralittoral, Capo San Vito, Trapani, NW. Sicily. 4,5mm.
110m deep, off Motril, Granada, Andalucia, S. Spain. 4,5mm.
Atlantic specimens are often fat.
Intertidal, Lanvéoc, Crozon peninsula, Finistère, W. Brittany, NW. France. 3-4mm.
In intertidal pools at low spring tide, Western Ledges near Wyke Regis, Portland Harbour, Dorset, S. United Kingdom.

— back to Rissoidae —