Rissoa parva
Costal ribs present (left) or absent (right). White labial varix with brown falciform mark (1), absent from juvenile (2). Aperture rim (3) not stained lilac. Protoconch has 3 or 4 white whorls (4), occasionally tinted lilac. Teleoconch whorls vary from slightly tumid (5) to distinctly tumid (6).
Translucent white cephalic tentacles have a thin, sometimes discontinuous, medial, opaque white line (7). Snout translucent whitish (8); sometimes has narrow black mark (9). Broad, transverse, dark band on foot (10).
Shell height of largest 3.1 mm. North Wales, March 2015 (left) and September 2011.
: flic.kr/p/2ogofx8
Sets of OTHER SPECIES: /