(Olivi, 1792)
Description (shell):
Shell solid, opaque, with three or four tumid whorls. Sculpture variable, either with strong V-shaped spiral striae, often symmetrical in profile, or with fine spirals giving a superficially smooth appearance. Aperture large, rounded, outer lip everted where it meets columella but not forming prominent spout. No umbilicus or umbilical groove (L. saxatilis-drawing).
The taxonomy of the L. saxatilis complex (nigrolineata, neglecta, arcana, saxatilis, rudis and tenebrosa ) has received a great deal of attention over a number of years and while the separation of Littorina nigrolineata, Littorina neglecta and Littorina arcana from L. saxatilis has achieved general approval, there is still some uncertainty as to the relationship and status of the residual trio of L. saxatilis, Littorina rudis and Littorina tenebrosa.
(L. sax. tenebrosa).
Size:
Up to 18 x 14 mm.
Colour:
Colour variable, usually with some pattern (tessellation or spiral lines) and with dark throat.
Animal:
Ovoviviparous. Extensive ciliary field (red in live animals) between genital tract and edge of columella muscle; prostate extends beyond anus, penis with elongate tip and variable number (4-26) of small glands arranged in one or two rows along its length but rarely extending to its curved base.
Habitat:
In thePelvetia zone and above, in crevices and empty barnacle shells.
Distribution:
Widely distributed, from Mediterranean to Arctic (Distr. L. saxatilis).