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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: 13

species Rissoa margiminia F. Nordsieck, 1972
species Rissoa marginata Michaud, 1832
species Rissoa melanostoma Requien, 1848
species Rissoa melanostomoides F. Nordsieck & F. G. García-Talavera, 1979
species Rissoa membranacea J. Adams, 1800

Rissoa membranacea

species Rissoa minuscula A. W. B. Powell, 1955 New Zealand
species Rissoa mirabilis Manzoni, 1868
species Rissoa mobilicosta W. F. Ponder, 1967
species Rissoa monodonta Philippi, 1836
species Rissoa monterosatoi Pallary, 1906
species Rissoa multicincta Smriglio & Mariottini, 1995
species Rissoa multicostata F. Nordsieck & F. G. García-Talavera, 1979
species Rissoa munda T. A. di Monterosato, 1884

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