Rissoa

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.

Habitat

This species can be found on brown algae, 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, 1985Rissoa acerosa Seguenza, 1903Rissoa acutata Schauroth, 1857 †Rissoa acuticosta † Rissoa acuticosta Von Koenen, 1892 †Rissoa adela d'Orbigny, 1852 †Rissoa aethiopica Thiele, 1925Rissoa albugo Watson, 1873

† Rissoa alienocurta Lozouet, 1998 Rissoa alleryi Rissoa alpina Gümbel, 1861 †Rissoa angusticostata Sandberger, 1860 †Rissoa angustior Rissoa anomala Eichwald, 1830 †Rissoa arata Philippi, 1849Rissoa athymorhyssa Dall, 1892 †Rissoa auriculata Seguenza, 1903Rissoa auriformis Pallary, 1904Rissoa auriscalpium Rissoa australis G. B. Sowerby II, 1877Rissoa baldacconii Cantraine, 1842 †Rissoa balliae W. Thompson, 1840Rissoa banatica Jekelius, 1944 †Rissoa basisulcata Etheridge & Bell in Bell, 1898 †Rissoa becki W. H. Turton, 1933Rissoa bissulca Buvignier, 1843 †Rissoa boytonensis Harmer, 1925 †Rissoa buccinalis †Rissoa callistrophia Dall, 1892 †Rissoa candidata W. H. Turton, 1932Rissoa certa Svagrovský, 1971 †Rissoa clotho Hörnes, 1856 †Rissoa conica L. Périer, 1867Rissoa conuloidea Etheridge & Bell in Bell, 1893 †Rissoa cooperi Tryon, 1865Rissoa costeiensis Kowalke & Harzhauser, 2004 †Rissoa costellata Grateloup, 1838 †Rissoa crefeldensis Wiechmann, 1874 †Rissoa crux Eichwald, 1853 †Rissoa cureti Cossmann, 1918 †Rissoa curta Dall, 1927: Rissoa curticostata S. V. Wood, 1848 †Rissoa cylindrella Odhner, 1924Rissoa decipiens Deshayes, 1861 †Rissoa decorata Philippi, 1846Rissoa decorticata Landau, Ceulemans & Van Dingenen, 2018 †Rissoa degrangei †Rissoa densecosta Etheridge & Bell in Bell, 1893 †Rissoa dilemma O. Boettger, 1907 †Rissoa dissimilis Harmer, 1920 †Rissoa dobrogica Necrasov, 1936Rissoa duboisii Nyst, 1845 †Rissoa dupiniana d'Orbigny, 1842 †Rissoa electrae Manousis, 2019Rissoa elegantula Piette, 1857 †Rissoa epulata Pilsbry & C. W. Johnson, 1917 †
Rissoa eurydictium Cossmann, 1888 †Rissoa euxinica Milaschevich, 1909Rissoa exigua Eichwald, 1830 †Rissoa flexuosa Von Koenen, 1892 †Rissoa fragilis †Rissoa fraterna Wiechmann, 1874 †Rissoa frauenfeldiana Brusina, 1868Rissoa gemmula Fischer P. in de Folin, 1869Rissoa geraea Dall, 1892 †Rissoa gibsoni T. Brown, 1841 †Rissoa glabrata G. B. Sowerby II, 1859Rissoa goepperti Schauroth, 1857 †Rissoa gomerica Rissoa gracilicosta Etheridge & Bell in Bell, 1893 †Rissoa granulum Philippi, 1844 Rissoa guerinii Récluz, 1843Rissoa guernei Dautzenberg, 1889Rissoa harmeri Faber, 2018 †Rissoa hebes O. Boettger, 1907 †Rissoa hidasensis Csepreghy-Meznerics, 1950 †Rissoa houdasi Cossmann, 1907Rissoa ilca Thiele, 1925Rissoa inchoata Deshayes, 1861 †Rissoa incompta A. A. Gould, 1862Rissoa incrassata J. Müller, 1851 †Rissoa inflexicosta †Rissoa infrastriolata Thiele, 1925Rissoa innocens W. H. Turton, 1932Rissoa intermedia Grateloup, 1838 †Rissoa intusstriata Etheridge & Bell in Bell, 1893 †Rissoa irritans Thiele, 1925Rissoa italiensis Verduin, 1985Rissoa janusi Rissoa jurensis Etallon, 1862 †Rissoa karsteni R. Janssen, 1978 †Rissoa latior Rissoa leighi T. Brown, 1841 †Rissoa lia Rissoa lilacina Récluz, 1843Rissoa lipeus Dall, 1892 †Rissoa lusoria Yokoyama, 1926 †Rissoa macra R. B. Watson, 1886Rissoa maya Yokoyama, 1926 †Rissoa membranacea
Rissoa microcharia Dall, 1892 †Rissoa mirabilis Manzoni, 1868Rissoa misera Deshayes, 1861 †Rissoa mitreola Eichwald, 1853 †Rissoa modesta Rissoa monodonta Philippi, 1836Rissoa moreana Buvignier, 1852 †Rissoa mosensis Buvignier, 1852 †Rissoa mucronata Svagrovský, 1971 †Rissoa multicincta Rissoa multicostata Rissoa munieri Szöts, 1953 †Rissoa nina Nordsieck, 1972 Rissoa obeliscoides Landau, Ceulemans & Van Dingenen, 2018 †Rissoa obeliscus May, 1915Rissoa obtusa T. Brown, 1841 †Rissoa olangoensis Poppe, Tagaro & Stahlschmidt, 2015 Rissoa oldhamiana Stoliczka, 1867 †Rissoa ovulum Philippi, 1844 †Rissoa pachia R. B. Watson, 1886Rissoa panhormensis Verduin, 1985Rissoa papuana Tapparone Canefri, 1877Rissoa paradoxa Rissoa parva Rissoa patens A. A. Gould, 1862Rissoa paupera Thiele, 1925Rissoa peregra Thiele, 1925Rissoa perforata Thiele, 1925Rissoa perspecta E. A. Smith, 1904Rissoa phagon J. A. Gardner, 1947 †Rissoa plagiostoma Thiele, 1925Rissoa plica Can, 18444traine, 1842Rissoa pompholyx Dall, 1927Rissoa poustagnacensis Lozouet, 1998 †Rissoa pouweri Van Dingenen, Ceulemans & Landau, 2016 †Rissoa proditoris Thiele, 1925Rissoa pseudoguerini Rissoa pseudoturricula Strausz, 1966 †Rissoa pucilla T. Brown, 1841 †Rissoa punctatissima R. Janssen, 1978 †Rissoa punctum Cantraine, 1842Rissoa quantilla W. H. Turton, 1932Rissoa quarantellii Brunetti & Vecchi, 2005 †Rissoa reussi Geinitz, 1875 †Rissoa rimata Philippi, 1844 †Rissoa robusta Rissoa rodhensis Verduin, 1985Rissoa rufa Philippi, 1849Rissoa rufanensis W. H. Turton, 1933Rissoa rugosa Svagrovský, 1971 †Rissoa rustica R. B. Watson, 1886Rissoa sadoensis Yokoyama, 1926 †Rissoa sandbergeri J. Müller, 1851 †Rissoa sarae Brunetti, Cresti & Forli, 2017 †Rissoa scurra Rissoa scutula Bell, 1892 †Rissoa searlesii Harmer, 1925 †Rissoa seguenzorum Bertolaso & Palazzi, 2000 †Rissoa selseyensis Harmer, 1925 †Rissoa semicarinata de Folin, 1870Rissoa semilaevis Von Koenen, 1892 †Rissoa senecta S. V. Wood, 1872 †Rissoa siberutensis Thiele, 1925Rissoa similis Scacchi, 1836Rissoa sismondiana Issel, 1869Rissoa sobieskii Friedberg, 1923 †Rissoa soceni Jekelius, 1944 †Rissoa solidula Philippi, 1849Rissoa sordida W. H. Turton, 1932Rissoa sowerbyi W. H. Turton, 1932Rissoa spinosa Seguenza †Rissoa splendida Eichwald, 1830Rissoa 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, 1876Rissoa sumatrana Thiele, 1925Rissoa sundaica Thiele, 1925Rissoa suttonensis Harmer, 1925 †Rissoa tenuilineata †Rissoa terebellum Philippi, 1844 †Rissoa terebralis Grateloup, 1838 †Rissoa teres W. H. Turton, 1932Rissoa texta Borchert, 1901 Rissoa tirolensis Koken in Wöhrmann & Koken, 1892 †Rissoa tomlini W. H. Turton, 1933Rissoa torquata Landau, Ceulemans & Van Dingenen, 2018 †Rissoa torquilla Pallary, 1912Rissoa trabeata Weisbord, 1962 †Rissoa triasina Schauroth, 1857 †Rissoa tristriata W. Thompson, 1840Rissoa tritonia W. H. Turton, 1932Rissoa tropica Stoliczka, 1868 †Rissoa turbinata †Rissoa turbinopsis Deshayes, 1861 †Rissoa turricula Eichwald, 1830 †Rissoa umbilicata Philippi, 1851Rissoa undulata Deshayes, 1861 †Rissoa unisulca Buvignier, 1843 †Rissoa valfini Guirand & Ogérien, 1865 †Rissoa variabilis Rissoa velata Zekeli, 1852 †Rissoa ventricosa Desmarest, 1814Rissoa venus d'Orbigny, 1852 †Rissoa venusta Philippi, 1844Rissoa verdensis Rolán & Oliveira, 2008Rissoa vicina Milaschevich, 1909Rissoa violacea Desmarest, 1814Rissoa 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 Rissoa albella Lovén, 1846: synonym of Pusillina sarsii Rissoa albella Alder, 1844: synonym of Rissoella diaphana Rissoa albida C. B. Adams, 1845: synonym of Zebinella albida Rissoa albolirata Carpenter, 1864: synonym of Lirobarleeia albolirata Rissoa alifera Thiele, 1925: synonym of Hoplopteron alifera Rissoa alveata Melvill & Standen, 1901: synonym of Iravadia quadrasi Rissoa atomus E. A. Smith, 1890 : synonym of Eatonina fulgida Rissoa australis Watson, 1886: synonym of Powellisetia australis Rissoa basispiralis Grant-Mackie & Chapman-Smith, 1971 † a: synonym of Diala semistriata Rissoa boscii : synonym of Melanella polita Rissoa calathus Forbes & Hanley, 1850: synonym of Alvania beanii Rissoa candidissima Webster, 1905 : synonym of Subonoba candidissima Rissoa carnosa Webster, 1905: synonym of Fictonoba carnosa Rissoa cazini Vélain, 1877: synonym of Pisinna cazini Rissoa cerithinum Philippi, 1849: synonym of Cerithidium cerithinum Rissoa columna Pelseneer, 1903: synonym of Onoba kergueleni Rissoa corilea G. B. Sowerby II, 1876: synonym of Stosicia corilea Rissoa coronata Scacchi, 1844: synonym of Opalia hellenica Rissoa costata : synonym of Manzonia crassa Rissoa costulata Alder, 1844: synonym of Rissoa guerinii Récluz, 1843Rissoa crassicostata C. B. Adams, 1845: synonym of Opalia hotessieriana Rissoa deserta E.A. Smith, 1907: synonym of Powellisetia deserta Rissoa diaphana Alder, 1848: synonym of Rissoella diaphana Rissoa dolium Nyst, 1845: synonym of Pusillina philippi Rissoa dubiosa C. B. Adams, 1850: synonym of Schwartziella dubiosa Rissoa edgariana Melvill & Standen, 1907: synonym of Rissoa parva Rissoa edwardiensis Watson, 1886: synonym of Skenella edwardiensis Rissoa emarginata Hutton, 1885: synonym of Nozeba emarginata Rissoa emblematica Hedley, 1906: synonym of Emblanda emblematica Rissoa eulimoides : synonym of Melanella eulimoides Rissoa filostria Melvill & Standen, 1912: synonym of Onoba filostria Rissoa finckhi Hedley, 1899: synonym of Chrystella finckhi Rissoa garretti Tate, 1899: synonym of Iravadia quadrasi Rissoa georgiana Pfeffer, 1886: synonym of Onoba georgiana Rissoa gracilis Pease, 1860: synonym of Pyramidelloides angustus Rissoa griegi Friele, 1879: synonym of Cingula griegi Rissoa grisea Martens, 1885: synonym of Onoba grisea Rissoa inconspicua Alder, 1844: synonym of Pusillina inconspicua Rissoa inconspicua C. B. Adams, 1852: synonym of Alvania monserratensis Baker, Hanna & Strong, 1930Rissoa inflatella Thiele, 1912: synonym of Onoba inflatella Rissoa infrequens C. B. Adams, 1852: synonym of Opalia infrequens Rissoa integella Hedley, 1904: synonym of Attenuata integella Rissoa interrupta : synonym of Rissoa parva Rissoa janmayeni Friele, 1878: synonym of Frigidoalvania janmayeni Rissoa kelseyi Dall & Bartsch, 1902: synonym of Lirobarleeia kelseyi Rissoa kergueleni E. A. Smith, 1875: synonym of Onoba kergueleni Rissoa labiosa : synonym of Rissoa membranacea Rissoa laevigata C. B. Adams, 1850: synonym of Zebina browniana Rissoa lantzi Vélain, 1877: synonym of Onoba lantzi Rissoa lineolata Michaud, 1830: synonym of Pusillina lineolata Rissoa lirata Carpenter, 1857: synonym of Lirobarleeia lirata Rissoa marionensis Watson, 1886: synonym of Eatoniella subrufescens Rissoa miliaris Thiele, 1912: synonym of Skenella sinapi Rissoa observationis Thiele, 1912: synonym of Onoba kergueleni Rissoa ordinaria E. A. Smith, 1890: synonym of Eatoniella ordinaria Rissoa paucilirata Melvill & Standen, 1912: synonym of Onoba paucilirata Rissoa pelseneeri Thiele, 1912: synonym of Powellisetia pelseneeri Rissoa porifera : synonym of Rissoa lilacina Récluz, 1843Rissoa principis Watson, 1886: synonym of Powellisetia principis Rissoa proxima Forbes & Hanley, 1850: synonym of Ceratia proxima Rissoa punctatostriata Tenison Woods, 1879: synonym of Leucotina casta Rissoa punctulum Philippi, 1836: synonym of Pisinna glabrata Rissoa rufilabris Alder, 1844: synonym of Rissoa lilacina Récluz, 1843Rissoa rufilabrum Alder, 1844: synonym of Rissoa lilacina Récluz, 1843Rissoa sarsii Lovén, 1846: synonym of Pusillina sarsii Rissoa scalarella C. B. Adams, 1845: synonym of Schwartziella scalarella Rissoa scotiana Melvill & Standen, 1907: synonym of Onoba semicostata Rissoa semistriata Philippi, 1849: synonym of Diala semistriata Rissoa sinapi Watson, 1886: synonym of Skenella sinapi Rissoa sinuosa Scacchi, 1836: synonym of Melanella sinuosa Rissoa striata : synonym of Onoba semicostata Rissoa striatula Jeffreys, 1847: synonym of Ceratia proxima Rissoa studeriana Thiele, 1912: synonym of Onoba steineni Rissoa suavis Thiele, 1925: synonym of Onoba suavis Rissoa subangulata C.B. Adams, 1850: synonym of Schwartziella bryerea Rissoa subantarctica Thiele, 1912: synonym of Onoba subantarctica Rissoa subcostulata Schwartz, 1864: synonym of Rissoa guerinii Récluz, 1843Rissoa subtruncata Pelseneer, 1903: synonym of Powellisetia pelseneeri Rissoa subtruncata Vélain, 1877: synonym of Scrobs subtruncata Rissoa syngenes : synonym of Alvania syngenes Rissoa transenna Watson, 1886: synonym of Onoba transenna Rissoa valdiviae Thiele, 1925: synonym of Onoba steineni Rissoa venusta Garrett, 1873: synonym of Iravadia quadrasi Rissoa vitrea C. B. Adams, 1850: synonym of Zebina vitrea Rissoa xanthias Watson, 1886: synonym of Benthonellania xanthias Rissoa xanthias var. acuticostata Dall, 1889: synonym of ''Benthonellania acuticostata''