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
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 albida C. B. Adams, 1845: synonym of Zebinella albida (C. B. Adams, 1845) 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 corilea G. B. Sowerby II, 1876: synonym of Stosicia corilea (G. B. Sowerby II, 1876) 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)