Familia Rissoidae

Gray, 1847

Shell small (typically 4-5 mm or less), with a conical spire; aperture ear-shaped or oval, usually with a complete peristome; operculum spiral and horny. Shell sculpture variable: smooth, or with spiral striae, costae or reticulations; may vary within species according to environmental conditions. Body with long bifid snout; mantle edge smooth, with one or two pallial tentacles. Foot folds transversely, the posterior sole having a median mucus gland; a single metapodial tentacle projects from below the rear of the operculum.

Source: Hayward et al., 1990.

The following subtaxa of this family occur in the region:

Genus Alvania
Alvania abyssicola
Alvania beani
Alvania cimicoides
Alvania jeffreysi
Alvania lactea
Alvania punctura
Alvania subsoluta
Genus Cingula
Cingula trifasciata
Genus Crisilla
Crisilla semistriata
Genus Manzonia
Manzonia crassa
Genus Obtusella
Obtusella intersecta
Genus Onoba
Onoba aculea
Onoba semicostata
Genus Pusillina
Pusillina inconspicua
Pusillina sarsii
Genus Rissoa
Rissoa lilacina
Rissoa membranacea
Rissoa parva
Rissoa porifera

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