Halistylus

Halistylus is a genus of very small sea snails, marine gastropod mollusks in the family Trochidae, the top snails.^[1]

Halistylus
Two shells of Halistylus columna
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Vetigastropoda
Order:	Trochida
Superfamily:	Trochoidea
Family:	Trochidae
Genus:	Halistylus Dall, 1890
Type species
Cantharidus columna Dall, 1890

Description

The small, polychromatic shell has a cylindrical shape. It is holostomatous, i.e. the aperture is rounded or entire, uninterrupted by the siphonal canal, notch, or by any other extension. The operculum is multispiral and coriaceous. There is no spiral sculpture. Such a cylindrical shape is rather uncommon in the family Trochidae. But the belonging of this genus to this family is certified by the shell structure, the pearly aperture and anatomical features.^[2]

This genus was previously considered a subgenus of the genus Cantharidus Montfort

Species

Species within the genus Halistylus include:

• Halistylus columna (Dall, 1890)
• Halistylus genecoani McLean, 1984
• Halistylus pupoideus (Carpenter, 1864)

Species brought into synonymy

• Halistylus circumstriatus Pilsbry, H.A., 1897: synonym of Halistylus columna (Dall, 1890)
• Halistylus pupoides: synonym of Halistylus pupoideus (Carpenter, 1864)