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Taxon profile

genus

Alvania Risso, 1826

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  order Caenogastropoda »  family Rissoidae

Description

Shell: minute to small, elongate-conic to turbiniform. Outer lip opisthocline to prosocline, with or without varix, thickened or thin, with or without denticles internally; peristome simple in most species, with or without weak posterior sinus. Axial and spiral sculpture present, sometimes spiral sculpture alone distinct; axial ribs usually continue over base but are weaker than on remainder of body whorl. Protoconch of 1 1/2 to more than 2 1/2 whorls, sculptured with raised dots to a few very strong spiral keels, often with irregular raised lines and dots in combination. Apex generally not strongly tilted in species with paucispiral protoconch.
Head Foot: cephalic tentacles long, ciliated, with parallel sides, anterior and posterior pallial tentacles present in most species; metapodial tentacles, in most species, 3-7. Anterior pedal gland present, posterior pedal gland usually inconspicuous and possibly absent in a few species.
Operculum: simple, thin, nucleus eccentric, paucispiral.
Ponder, 1985. A review of the genera of the Rissoidae.

Distribution

World-wide except Antarctic and Subantarctic regions. Upper Cretaceous (?) to Recent

Interchangeable taxa

The opercular, sculptural and radular characters of of Alvania are similar to those of Rissoa. The external features of the animal of species of Alvania are somewhat similar to those of Rissoa but the sole is often less distinctly partitioned into anterior and posterior segments, the posterior mucous gland is sometimes indistinct and has a relatively small opening, there are always 2 (not 1-2) pallial tentacles (anterior and posterior) and 3-7 (not 1) metapodial tentacles.
Ponder, 1985. A review of the genera of the Rissoidae.
Author: Jan Delsing

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Subordinated taxa

Number of records: 4

species Alvania venter F. Nordsieck, 1972
species Alvania verduini J. J. van Aartsen, 1983
species Alvania vermaasi Van Aartsen, 1975
species Alvania villarii Micali, Tisselli & Giunchi, 2004

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