Rissoa Geraea

''Rissoa'' is a genus of minute sea snails, marine gastropod mollusks or micromollusks in the family Rissoidae.

The genus was first introduced by M. de Freminville for some small shells observed by M. Antoine Risso, a distinguished naturalist of Nice, France. They were described by M. Demarest in 1814 in the "New Bulletin of the Philomatic Society".

Description

The soft body of the snail is elongated and spiral. The somewhat prolonged mouth has a proboscis. The tentacles are awl-shaped with the eyes on a small prominence near the base. The foot is oval or elliptical. The species is phytophagous.

The conical shell has an elongated spire with its apex nipple-shaped. The size of the shell varies between 1 mm and 8 mm. The whorls are generally convex-shaped with a distinct suture. The aperture is ovate, roundish or pear-shaped with its anterior end rounded, the posterior end acute and with the peristome complete. The thin and horny operculum is spirally marked and equally ovate, roundish or pear-shaped. Macgillivray, William, History of the molluscous animals of Scotland, London, 1844
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Habitat

This species can be found on brown algae (genus ''Fucus''), in clefts of rocks, on stones, on mud or sand. Most will be found on sandy beaches along the line of the last tide.

Species

Species within the genus ''Rissoa'' include:

* ''Rissoa aartseni'' Verduin, 1985
* '' Rissoa acerosa'' Seguenza, 1903
* ''Rissoa acutata'' Schauroth, 1857 †
* ''Rissoa acuticosta'' (Sacco, 1895) † (Homonymy junior secondary homonym of R. acuticosta Von Koenen, 1892, which seems to be a true Rissoa)
* ''Rissoa acuticosta'' Von Koenen, 1892 †
* ''Rissoa adela'' d'Orbigny, 1852 †
* ''Rissoa aethiopica'' Thiele, 1925
* ''Rissoa albugo'' Watson, 1873
* † ''Rissoa alienocurta'' Lozouet, 1998
* ''Rissoa alleryi'' (Nordsieck, 1972)
* '' Rissoa alpina'' Gümbel, 1861 †
* ''Rissoa angusticostata'' Sandberger, 1860 †
* '' Rissoa angustior'' (Monterosato, 1917) (taxon inquirendum)
* ''Rissoa anomala'' Eichwald, 1830 †
* ''Rissoa arata'' Philippi, 1849
* '' Rissoa athymorhyssa'' Dall, 1892 †
* '' Rissoa auriculata'' Seguenza, 1903
* ''Rissoa auriformis'' Pallary, 1904
* ''Rissoa auriscalpium'' (Linnaeus, 1758)
* ''Rissoa australis'' G. B. Sowerby II, 1877
* '' Rissoa baldacconii'' Cantraine, 1842 †
* ''Rissoa balliae'' W. Thompson, 1840
* ''Rissoa banatica'' Jekelius, 1944 †
* ''Rissoa basisulcata'' Etheridge & Bell in Bell, 1898 †
* ''Rissoa becki'' W. H. Turton, 1933
* ''Rissoa bissulca'' Buvignier, 1843 †
* ''Rissoa boytonensis'' Harmer, 1925 †
* ''Rissoa buccinalis'' (Lamarck, 1804) †
* '' Rissoa callistrophia'' Dall, 1892 †
* ''Rissoa candidata'' W. H. Turton, 1932
* ''Rissoa certa'' Svagrovský, 1971 †
* ''Rissoa clotho'' Hörnes, 1856 †
* '' Rissoa conica'' L. Périer, 1867
* ''Rissoa conuloidea'' Etheridge & Bell in Bell, 1893 †
* ''Rissoa cooperi'' Tryon, 1865
* '' Rissoa costeiensis'' Kowalke & Harzhauser, 2004 †
* '' Rissoa costellata'' Grateloup, 1838 †
* ''Rissoa crefeldensis'' Wiechmann, 1874 †
* ''Rissoa crux'' Eichwald, 1853 †
* ''Rissoa cureti'' Cossmann, 1918 †
* ''Rissoa curta'' Dall, 1927: (taxon inquirendum, non Dujardin, 1837)
* ''Rissoa curticostata'' S. V. Wood, 1848 †
* '' Rissoa cylindrella'' Odhner, 1924
* ''Rissoa decipiens'' Deshayes, 1861 †
* ''Rissoa decorata'' Philippi, 1846
* ''Rissoa decorticata'' Landau, Ceulemans & Van Dingenen, 2018 †
* ''Rissoa degrangei'' (Cossmann & Peyrot, 1919) †
* ''Rissoa densecosta'' Etheridge & Bell in Bell, 1893 †
* '' Rissoa dilemma'' O. Boettger, 1907 †
* ''Rissoa dissimilis'' Harmer, 1920 †
* ''Rissoa dobrogica'' Necrasov, 1936
* ''Rissoa duboisii'' Nyst, 1845 †
* ''Rissoa dupiniana'' d'Orbigny, 1842 †
* ''Rissoa electrae'' Manousis, 2019
* ''Rissoa elegantula'' Piette, 1857 †
* ''Rissoa epulata'' Pilsbry & C. W. Johnson, 1917 †
* Rissoa eurydictium Cossmann, 1888 †
* ''Rissoa euxinica'' Milaschevich, 1909
* ''Rissoa exigua'' Eichwald, 1830 †
* ''Rissoa flexuosa'' Von Koenen, 1892 †
* ''Rissoa fragilis'' (Lamarck, 1804) †
* '' Rissoa fraterna'' Wiechmann, 1874 †
* ''Rissoa frauenfeldiana'' Brusina, 1868
* ''Rissoa gemmula'' Fischer P. in de Folin, 1869
* '' Rissoa geraea'' Dall, 1892 †
* ''Rissoa gibsoni'' T. Brown, 1841 †
* ''Rissoa glabrata'' G. B. Sowerby II, 1859
* ''Rissoa goepperti'' Schauroth, 1857 †
* ''Rissoa gomerica'' (Nordsieck & Talavera, 1979)
* '' Rissoa gracilicosta'' Etheridge & Bell in Bell, 1893 †
* ''Rissoa granulum'' Philippi, 1844 (taxon inquirendum)
* ''Rissoa guerinii'' Récluz, 1843
* ''Rissoa guernei'' Dautzenberg, 1889
* ''Rissoa harmeri'' Faber, 2018 †
* ''Rissoa hebes'' O. Boettger, 1907 †
* '' Rissoa hidasensis'' Csepreghy-Meznerics, 1950 †
* ''Rissoa houdasi'' Cossmann, 1907
* ''Rissoa ilca'' Thiele, 1925
* ''Rissoa inchoata'' Deshayes, 1861 †
* '' Rissoa incompta'' A. A. Gould, 1862
* ''Rissoa incrassata'' J. Müller, 1851 †
* ''Rissoa inflexicosta'' (Cossmann, 1921) †
* '' Rissoa infrastriolata'' Thiele, 1925
* '' Rissoa innocens'' W. H. Turton, 1932
* ''Rissoa intermedia'' Grateloup, 1838 †
* '' Rissoa intusstriata'' Etheridge & Bell in Bell, 1893 †
* '' Rissoa irritans'' Thiele, 1925
* ''Rissoa italiensis'' Verduin, 1985
* ''Rissoa janusi'' (Nordsieck, 1972)
* '' Rissoa jurensis'' Etallon, 1862 †
* '' Rissoa karsteni'' R. Janssen, 1978 †
* ''Rissoa latior'' (Mighels & C. B. Adams, 1844)
* ''Rissoa leighi'' T. Brown, 1841 †
* ''Rissoa lia'' (Monterosato, 1884)
* ''Rissoa lilacina'' Récluz, 1843
* '' Rissoa lipeus'' Dall, 1892 †
* ''Rissoa lusoria'' Yokoyama, 1926 †
* ''Rissoa macra'' R. B. Watson, 1886
* ''Rissoa maya'' Yokoyama, 1926 †
* ''Rissoa membranacea'' (Adams J., 1800)
* Rissoa microcharia Dall, 1892 †
* ''Rissoa mirabilis'' Manzoni, 1868
* ''Rissoa misera'' Deshayes, 1861 †
* ''Rissoa mitreola'' Eichwald, 1853 †
* ''Rissoa modesta'' (H. C. Lea, 1845)
* ''Rissoa monodonta'' Philippi, 1836
* '' Rissoa moreana'' Buvignier, 1852 †
* ''Rissoa mosensis'' Buvignier, 1852 †
* ''Rissoa mucronata'' Svagrovský, 1971 †
* ''Rissoa multicincta'' (Smriglio & Mariottini, 1995)
* ''Rissoa multicostata'' (Nordsieck & Talavera, 1979)
* ''Rissoa munieri'' Szöts, 1953 †
* ''Rissoa nina'' Nordsieck, 1972 (nomen dubium)
* ''Rissoa obeliscoides'' Landau, Ceulemans & Van Dingenen, 2018 †
* '' Rissoa obeliscus'' May, 1915
* '' Rissoa obtusa'' T. Brown, 1841 †
* '' Rissoa olangoensis'' Poppe, Tagaro & Stahlschmidt, 2015
* ''Rissoa oldhamiana'' Stoliczka, 1867 †
* ''Rissoa ovulum'' Philippi, 1844 †
* ''Rissoa pachia'' R. B. Watson, 1886
* ''Rissoa panhormensis'' Verduin, 1985
* ''Rissoa papuana'' Tapparone Canefri, 1877
* ''Rissoa paradoxa'' (Monterosato, 1884)
* ''Rissoa parva'' (da Costa, 1778)
* ''Rissoa patens'' A. A. Gould, 1862
* ''Rissoa paupera'' Thiele, 1925
* ''Rissoa peregra'' Thiele, 1925
* ''Rissoa perforata'' Thiele, 1925
* ''Rissoa perspecta'' E. A. Smith, 1904
* ''Rissoa phagon'' J. A. Gardner, 1947 †
* ''Rissoa plagiostoma'' Thiele, 1925
* ''Rissoa plica'' Can, 18444traine, 1842
* '' Rissoa pompholyx'' Dall, 1927
* ''Rissoa poustagnacensis'' Lozouet, 1998 †
* ''Rissoa pouweri'' Van Dingenen, Ceulemans & Landau, 2016 †
* ''Rissoa proditoris'' Thiele, 1925
* ''Rissoa pseudoguerini'' (Nordsieck & Talavera, 1979)
* '' Rissoa pseudoturricula'' Strausz, 1966 †
* ''Rissoa pucilla'' T. Brown, 1841 †
* '' Rissoa punctatissima'' R. Janssen, 1978 †
* '' Rissoa punctum'' Cantraine, 1842
* ''Rissoa quantilla'' W. H. Turton, 1932
* ''Rissoa quarantellii'' Brunetti & Vecchi, 2005 †
* '' Rissoa reussi'' Geinitz, 1875 †
* ''Rissoa rimata'' Philippi, 1844 †
* ''Rissoa robusta'' (H. C. Lea, 1845)
* ''Rissoa rodhensis'' Verduin, 1985
* ''Rissoa rufa'' Philippi, 1849
* ''Rissoa rufanensis'' W. H. Turton, 1933
* ''Rissoa rugosa'' Svagrovský, 1971 †
* '' Rissoa rustica'' R. B. Watson, 1886
* ''Rissoa sadoensis'' Yokoyama, 1926 †
* ''Rissoa sandbergeri'' J. Müller, 1851 †
* '' Rissoa sarae'' Brunetti, Cresti & Forli, 2017 †
* ''Rissoa scurra'' (Monterosato, 1917)
* ''Rissoa scutula'' Bell, 1892 †
* ''Rissoa searlesii'' Harmer, 1925 †
* '' Rissoa seguenzorum'' Bertolaso & Palazzi, 2000 †
* '' Rissoa selseyensis'' Harmer, 1925 †
* '' Rissoa semicarinata'' de Folin, 1870
* ''Rissoa semilaevis'' Von Koenen, 1892 †
* ''Rissoa senecta'' S. V. Wood, 1872 †
* ''Rissoa siberutensis'' Thiele, 1925
* '' Rissoa similis'' Scacchi, 1836
* ''Rissoa sismondiana'' Issel, 1869
* '' Rissoa sobieskii'' Friedberg, 1923 †
* ''Rissoa soceni'' Jekelius, 1944 †
* ''Rissoa solidula'' Philippi, 1849
* ''Rissoa sordida'' W. H. Turton, 1932
* ''Rissoa sowerbyi'' W. H. Turton, 1932
* ''Rissoa spinosa'' Seguenza †
* ''Rissoa splendida'' Eichwald, 1830
* '' Rissoa striatula'' Eichwald, 1830 †
* '' Rissoa strombecki'' Schauroth, 1857 †
* ''Rissoa subcarinta'' Cantraine, 1842 †
* ''Rissoa subclathrata'' Buvignier, 1852 †
* ''Rissoa sublachesis'' Zhizhchenko, 1936 †
* ''Rissoa submarginata'' d'Orbigny, 1850 †
* '' Rissoa subperforata'' Jeffreys, 1884 †
* ''Rissoa sulcifera'' G. B. Sowerby II, 1876
* ''Rissoa sumatrana'' Thiele, 1925
* ''Rissoa sundaica'' Thiele, 1925
* ''Rissoa suttonensis'' Harmer, 1925 †
* ''Rissoa tenuilineata'' (Cossmann, 1921) †
* '' Rissoa terebellum'' Philippi, 1844 †
* ''Rissoa terebralis'' Grateloup, 1838 †
* ''Rissoa teres'' W. H. Turton, 1932
* ''Rissoa texta'' Borchert, 1901
* '' Rissoa tirolensis'' Koken in Wöhrmann & Koken, 1892 †
* ''Rissoa tomlini'' W. H. Turton, 1933
* ''Rissoa torquata'' Landau, Ceulemans & Van Dingenen, 2018 †
* ''Rissoa torquilla'' Pallary, 1912
* ''Rissoa trabeata'' Weisbord, 1962 †
* ''Rissoa triasina'' Schauroth, 1857 †
* ''Rissoa tristriata'' W. Thompson, 1840
* ''Rissoa tritonia'' W. H. Turton, 1932
* ''Rissoa tropica'' Stoliczka, 1868 †
* ''Rissoa turbinata'' (Lamarck, 1804) †
* '' Rissoa turbinopsis'' Deshayes, 1861 †
* ''Rissoa turricula'' Eichwald, 1830 †
* ''Rissoa umbilicata'' Philippi, 1851
* ''Rissoa undulata'' Deshayes, 1861 †
* ''Rissoa unisulca'' Buvignier, 1843 †
* ''Rissoa valfini'' Guirand & Ogérien, 1865 †
* ''Rissoa variabilis'' (Von Mühlfeldt, 1824)
* ''Rissoa velata'' Zekeli, 1852 †
* ''Rissoa ventricosa'' Desmarest, 1814
* ''Rissoa venus'' d'Orbigny, 1852 †
* ''Rissoa venusta'' Philippi, 1844
* ''Rissoa verdensis'' Rolán & Oliveira, 2008
* ''Rissoa vicina'' Milaschevich, 1909
* ''Rissoa violacea'' Desmarest, 1814
* ''Rissoa virdunensis'' Buvignier, 1852 †
* ''Rissoa winkleri'' Müller, 1851 †
* ''Rissoa ziga'' De Gregorio, 1890 †
* ''Rissoa zosta'' Bayan, 1873 †

Synonyms

* ''Rissoa adarensis'' E.A. Smith, 1902: synonym of ''Onoba kergueleni'' (E. A. Smith, 1875)
* ''Rissoa albella'' Lovén, 1846: synonym of ''Pusillina sarsii'' (Lovén, 1846)
* ''Rissoa albella'' Alder, 1844: synonym of '' Rissoella diaphana'' (Alder, 1848)
* ''Rissoa albolirata'' Carpenter, 1864: synonym of ''Lirobarleeia albolirata'' (Carpenter, 1864)
* ''Rissoa alifera'' Thiele, 1925: synonym of '' Hoplopteron alifera'' (Thiele, 1925)
* ''Rissoa alveata'' Melvill & Standen, 1901: synonym of '' Iravadia quadrasi'' (O. Boettger, 1893)
* ''Rissoa atomus'' E. A. Smith, 1890 : synonym of '' Eatonina fulgida'' (Adams J., 1797)
* ''Rissoa australis'' Watson, 1886: synonym of ''Powellisetia australis'' (Watson, 1886)
* ''Rissoa basispiralis'' Grant-Mackie & Chapman-Smith, 1971 † a: synonym of '' Diala semistriata'' (Philippi, 1849)
* ''Rissoa boscii'' (Payraudeau, 1826): synonym of ''Melanella polita'' (Linnaeus, 1758)
* ''Rissoa calathus'' Forbes & Hanley, 1850: synonym of ''Alvania beanii'' (Hanley in Thorpe, 1844)
* ''Rissoa candidissima'' Webster, 1905 : synonym of ''Subonoba candidissima'' (Webster, 1905)
* ''Rissoa carnosa'' Webster, 1905: synonym of '' Fictonoba carnosa'' (Webster, 1905)
* ''Rissoa cazini'' Vélain, 1877: synonym of '' Pisinna cazini'' (Vélain, 1877)
* ''Rissoa cerithinum'' Philippi, 1849: synonym of ''Cerithidium cerithinum'' (Philippi, 1849)
* ''Rissoa columna'' Pelseneer, 1903: synonym of ''Onoba kergueleni'' (E. A. Smith, 1875)
* ''Rissoa coronata'' Scacchi, 1844: synonym of '' Opalia hellenica'' (Forbes, 1844)
* ''Rissoa costata'' (J. Adams, 1796): synonym of ''Manzonia crassa'' (Kanmacher, 1798)
* ''Rissoa costulata'' Alder, 1844: synonym of ''Rissoa guerinii'' Récluz, 1843
* ''Rissoa crassicostata'' C. B. Adams, 1845: synonym of ''Opalia hotessieriana'' (d’Orbigny, 1842)
* ''Rissoa deserta'' E.A. Smith, 1907: synonym of ''Powellisetia deserta'' (E.A. Smith, 1907)
* ''Rissoa diaphana'' Alder, 1848: synonym of '' Rissoella diaphana'' (Alder, 1848)
* ''Rissoa dolium'' Nyst, 1845: synonym of '' Pusillina philippi'' (Aradas & Maggiore, 1844)
* ''Rissoa dubiosa'' C. B. Adams, 1850: synonym of ''Schwartziella dubiosa'' (C. B. Adams, 1850)
* ''Rissoa edgariana'' Melvill & Standen, 1907: synonym of ''Rissoa parva'' (da Costa, 1778)
* ''Rissoa edwardiensis'' Watson, 1886: synonym of '' Skenella edwardiensis'' (Watson, 1886)
* ''Rissoa emarginata'' Hutton, 1885: synonym of ''Nozeba emarginata'' (Hutton, 1885)
* ''Rissoa emblematica'' Hedley, 1906: synonym of ''Emblanda emblematica'' (Hedley, 1906)
* ''Rissoa eulimoides'' (C.B. Adams, 1850): synonym of ''Melanella eulimoides'' (C. B. Adams, 1850)
* ''Rissoa filostria'' Melvill & Standen, 1912: synonym of ''Onoba filostria'' (Melvill & Standen, 1912)
* ''Rissoa finckhi'' Hedley, 1899: synonym of '' Chrystella finckhi'' (Hedley, 1899)
* ''Rissoa garretti'' Tate, 1899: synonym of '' Iravadia quadrasi'' (O. Boettger, 1893)
* ''Rissoa georgiana'' Pfeffer, 1886: synonym of ''Onoba georgiana'' (Pfeffer, 1886)
* ''Rissoa gracilis'' Pease, 1860: synonym of ''Pyramidelloides angustus'' (Hedley, 1898)
* ''Rissoa griegi'' Friele, 1879: synonym of ''Cingula griegi'' (Friele, 1879)
* ''Rissoa grisea'' Martens, 1885: synonym of ''Onoba grisea'' (Martens, 1885)
* ''Rissoa inconspicua'' Alder, 1844: synonym of ''Pusillina inconspicua'' (Alder, 1844)
* ''Rissoa inconspicua'' C. B. Adams, 1852: synonym of ''Alvania monserratensis'' Baker, Hanna & Strong, 1930
* ''Rissoa inflatella'' Thiele, 1912: synonym of ''Onoba inflatella'' (Thiele, 1912)
* ''Rissoa infrequens'' C. B. Adams, 1852: synonym of ''Opalia infrequens'' (C. B. Adams, 1852)
* ''Rissoa integella'' Hedley, 1904: synonym of ''Attenuata integella'' (Hedley, 1904)
* ''Rissoa interrupta'' (J. Adams, 1800): synonym of ''Rissoa parva'' (da Costa, 1778)
* ''Rissoa janmayeni'' Friele, 1878: synonym of ''Frigidoalvania janmayeni'' (Friele, 1878)
* ''Rissoa kelseyi'' Dall & Bartsch, 1902: synonym of '' Lirobarleeia kelseyi'' (Dall & Bartsch, 1902)
* ''Rissoa kergueleni'' E. A. Smith, 1875: synonym of ''Onoba kergueleni'' (E. A. Smith, 1875)
* ''Rissoa labiosa'' ( Montagu, 1803): synonym of ''Rissoa membranacea'' (J. Adams, 1800)
* ''Rissoa laevigata'' C. B. Adams, 1850: synonym of '' Zebina browniana'' (d'Orbigny, 1842)
* ''Rissoa lantzi'' Vélain, 1877: synonym of ''Onoba lantzi'' (Vélain, 1877)
* ''Rissoa lineolata'' Michaud, 1830: synonym of ''Pusillina lineolata'' (Michaud, 1832)
* ''Rissoa lirata'' Carpenter, 1857: synonym of '' Lirobarleeia lirata'' (Carpenter, 1857)
* ''Rissoa marionensis'' Watson, 1886: synonym of '' Eatoniella subrufescens'' (E.A. Smith, 1875)
* ''Rissoa miliaris'' Thiele, 1912: synonym of '' Skenella sinapi'' (Watson, 1886)
* ''Rissoa observationis'' Thiele, 1912: synonym of ''Onoba kergueleni'' (E. A. Smith, 1875)
* ''Rissoa ordinaria'' E. A. Smith, 1890: synonym of '' Eatoniella ordinaria'' (E. A. Smith, 1890)
* ''Rissoa paucilirata'' Melvill & Standen, 1912: synonym of ''Onoba paucilirata'' (Melvill & Standen, 1912)
* ''Rissoa pelseneeri'' Thiele, 1912: synonym of ''Powellisetia pelseneeri'' (Thiele, 1912)
* ''Rissoa porifera'' (Lovén, 1843): synonym of ''Rissoa lilacina'' Récluz, 1843
* ''Rissoa principis'' Watson, 1886: synonym of '' Powellisetia principis'' (Watson, 1886)
* ''Rissoa proxima'' Forbes & Hanley, 1850: synonym of ''Ceratia proxima'' (Forbes & Hanley, 1850)
* ''Rissoa punctatostriata'' Tenison Woods, 1879: synonym of ''Leucotina casta'' (A. Adams, 1853)
* ''Rissoa punctulum'' Philippi, 1836: synonym of ''Pisinna glabrata'' (Von Mühlfeldt, 1824)
* ''Rissoa rufilabris'' Alder, 1844: synonym of ''Rissoa lilacina'' Récluz, 1843
* ''Rissoa rufilabrum'' Alder, 1844: synonym of ''Rissoa lilacina'' Récluz, 1843
* ''Rissoa sarsii'' Lovén, 1846: synonym of ''Pusillina sarsii'' (Lovén, 1846)
* ''Rissoa scalarella'' C. B. Adams, 1845: synonym of ''Schwartziella scalarella'' (C. B. Adams, 1845)
* ''Rissoa scotiana'' Melvill & Standen, 1907: synonym of ''Onoba semicostata'' ( Montagu, 1803)
* ''Rissoa semistriata'' Philippi, 1849: synonym of '' Diala semistriata'' (Philippi, 1849)
* ''Rissoa sinapi'' Watson, 1886: synonym of '' Skenella sinapi'' (Watson, 1886)
* ''Rissoa sinuosa'' Scacchi, 1836: synonym of ''Melanella sinuosa'' (Scacchi, 1836)
* ''Rissoa striata'' (J. Adams, 1797): synonym of ''Onoba semicostata'' ( Montagu, 1803)
* ''Rissoa striatula'' Jeffreys, 1847: synonym of ''Ceratia proxima'' (Forbes & Hanley, 1850)
* ''Rissoa studeriana'' Thiele, 1912: synonym of ''Onoba steineni'' (Strebel, 1908)
* ''Rissoa suavis'' Thiele, 1925: synonym of ''Onoba suavis