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Taxon profile

genus

Rissoa Freminville in Desmarest, 1814

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

Description

Shell: of small to large size, elongate conic, non-umbilicate; axial sculpture usually predominant, usually of prominent, broad ribs. Weak spiral threads often present, sometimes broad with spaces between them sunken to form shallow pits. Sculpture weak to moderately strong axial ribs; spiral cords weak, low, usually do not cross axial ribs; axials not terminated at periphery by a spiral cord but usually weak or absent on base; sometimes smooth. Aperture with shallow posterior sinus broadly rounded anteriorly; columella often thick, sometimes twisted. Outer lip opisthocline to prosocline, with weak to pronounced varix externally. Protoconch narrowly conic, edge sinuate, usually more than two whorls. Prodissoconch usually small, slightly tilted, sometimes sculptured with a few, very weak spiral threads which disappear before commencement of second whorl; otherwise smooth.
Ponder, 1985. A review of the genera of the Rissoidae.
Author: Jan Delsing

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Subordinated taxa

Number of records: 16

species Rissoa sarsi S. L. Lovén, 1846
species Rissoa scurra (Monterosato, 1917)
species Rissoa semireticulata R. Murdoch & H. Suter, 1906
species Rissoa sfaxiana F. Nordsieck, 1972
species Rissoa similis Scacchi, 1836
species Rissoa simplex R. A. Philippi, 1844
species Rissoa sinuastoma W. F. Ponder, 1967
species Rissoa splendida Eichwald, 1830
species Rissoa spongiocola T. A. di Monterosato, 1883
species Rissoa strangulata S. Brusina, 1865
species Rissoa stricta F. Nordsieck, 1972
species Rissoa subcostulata Schwartz, 1864
species Rissoa subradiata L. Seguenza, 1903
species Rissoa subsuturalis Dell, 1956
species Rissoa subventricosa Cantraine, 1842
species Rissoa syngenes Verrill, 1884

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