Integrated Taxonomic Information System - Search Results
Results of: Search in every Kingdom for Scientific Name containing 'Hydra'
 
 Kingdom Animalia
  Adelphydraena Perkins, 1989 – valid
  Adelphydraena orchymonti Perkins, 1989 – valid
  Adelphydraena spangleri Perkins, 1989 – valid
  Afissa hydrangeae (Pang and Mao, 1979) – valid
  Afissula hydrangeae Pang and Mao, 1979 – invalid
  Ankylocythere ephydra Hart and Hart, 1971 – valid
  Anodonta enhydra da Silva e Castro, 1885 – invalid
  Anodonta philhydra Péchaud, 1884 – invalid
  Apiocera parahydra Cazier, 1982 – valid
  Arenohydracaridae – valid
  Armorhydra Swedmark and Teissier, 1958 – valid
  Armorhydra janowiczi Swedmark and Teissier, 1958 – valid
  Asphondylia hydrangeae Felt, 1907 – valid
  Bathydraco Günther, 1878 – valid
  Bathydraco antarcticus Günther, 1878 – valid
  Bathydraco joannae DeWitt, 1985 – valid
  Bathydraco macrolepis Boulenger, 1907 – valid
  Bathydraco marri Norman, 1938 – valid
  Bathydraco scotiae Dollo, 1906 – valid
  Bathydraconidae – valid – dragonfishes, Antarctic dragonfishes
  Campsicnemus philohydratus Hardy, 1964 – valid
  Chlorohydra Schulze, 1917 – valid
  Chlorohydra hadleyi Forrest, 1959 – valid
  Chlorohydra viridissima (Pallas, 1766) – valid – green hydra
  Doto hydrallmaniae Marrow – valid
  Enhydra Fleming, 1822 – valid – sea otters
  Enhydra lutris (Linnaeus, 1758) – valid – Sea Otter, Nutria Marina
  Enhydra lutris kamtschatica Dybowski, 1922 – invalid
  Enhydra lutris kenyoni Wilson, 1991 – valid – Northern Sea Otter, Eastern Sea Otter
  Enhydra lutris lutris (Linnaeus, 1758) – valid – Sea Otter, Western Sea Otter
  Enhydra lutris nereis (Merriam, 1904) – valid – Southern Sea Otter
  Ephydra – valid
  Ephydra aquila Fallen, 1813 – invalid
  Ephydra atrovirens Loew, 1862 – invalid
  Ephydra auripes Aldrich, 1912 – valid
  Ephydra austrina Coquillett, 1900 – invalid
  Ephydra bruesi Cresson, 1934 – valid
  Ephydra californica Packard, 1871 – invalid
  Ephydra cesta Haliday, 1833 – invalid
  Ephydra cinerea Jones, 1906 – invalid
  Ephydra crassimana Loew, 1866 – invalid
  Ephydra cribrata Stenhammar, 1844 – invalid
  Ephydra currani Wirth, 1971 – valid
  Ephydra curvicauda Meigen, 1830 – invalid
  Ephydra despecta Haliday, 1839 – invalid
  Ephydra goedeni Wirth, 1971 – valid
  Ephydra gracilis Packard, 1871 – valid
  Ephydra halophila Packard, 1869 – invalid
  Ephydra hians Say, 1830 – valid
  Ephydra macellaria Egger, 1862 – valid
  Ephydra micans Haliday, 1833 – invalid
  Ephydra millbrae Jones, 1906 – valid
  Ephydra niveiceps Cresson, 1916 – valid
  Ephydra obscuripes Loew, 1866 – valid
  Ephydra octonotata Walker, 1849 – invalid
  Ephydra oscitans Walker, 1849 – invalid
  Ephydra pacifica Cresson, 1925 – invalid
  Ephydra packardi Wirth, 1971 – valid
  Ephydra paludum Meigen, 1830 – invalid
  Ephydra pectinulata Cresson, 1916 – valid
  Ephydra pentastigma Thomson, 1869 – invalid
  Ephydra picea Walker, 1849 – invalid
  Ephydra pilicornis Coquillett, 1902 – invalid
  Ephydra pinguis Walker, 1852 – invalid
  Ephydra pygmaea Haliday, 1833 – invalid
  Ephydra riparia Fallen, 1813 – valid
  Ephydra salina Curran, 1931 – invalid
  Ephydra spilota Curtis, 1832 – invalid
  Ephydra stagnalis Fallen, 1813 – invalid
  Ephydra stenhammari Zetterstedt, 1846 – invalid
  Ephydra striata Walker, 1849 – invalid
  Ephydra subopaca Loew, 1864 – valid
  Ephydra tarsata Williston, 1893 – invalid
  Ephydra thermophila Cresson, 1934 – valid
  Ephydra usingeri Wirth, 1976 – valid
  Fungiacyathus hydra Zibrowius and Gili, 1990 – valid
  Galathea hydrae Macpherson & Robainas-Barcia, 2015 – valid
  Halammohydra Remane, 1927 – valid
  Halammohydra adherens Swedmark and Teissier, 1958 – valid
  Halammohydra octopodides Remane, 1927 – valid
  Halammohydra schulzei Remane, 1927 – valid
  Halammohydra vermiformis Swedmark and Teissier, 1957 – valid
  Hungarohydracaridae – valid
  Hydra Linnaeus, 1758 – valid
  Hydra americana Hyman, 1929 – valid – white hydra
  Hydra canadensis Rowan, 1930 – valid – Alberta hydra
  Hydra carnea L. Agassiz, 1850 – valid
  Hydra cauliculata Hyman, 1938 – valid
  Hydra hymanae Hadley and Forrest, 1949 – valid – Jersey hydra
  Hydra littoralis Hyman, 1931 – valid – swiftwater hydra
  Hydra minima Forrest, 1963 – valid
  Hydra oligactis Pallas, 1766 – valid – brown hydra
  Hydra oregona Griffin and Peters, 1939 – valid – Oregon hydra
  Hydra pseudoligactis (Hyman, 1931) – valid – false brown hydra
  Hydra rutgerensis Forrest, 1963 – valid
  Hydra rutgersensis Forrest, 1963 – valid
  Hydra utahensis Hyman, 1931 – valid – Utah hydra
  Hydrablabes Boulenger, 1891 – valid
  Hydrablabes periops (Günther, 1872) – valid – Olive Small-eyed Snake
  Hydrablabes praefrontalis (Mocquard, 1890) – valid – Mocquard's Small-eyed Snake
  Hydrablables Boulenger, 1891 – invalid
  Hydrablables periops (Günther, 1872) – invalid
  Hydrablables praefrontalis (Mocquard, 1890) – invalid
  Hydrachna O. F. Müller, 1776 – valid
  Hydrachna baculoscutata Crowell, 1960 – valid
  Hydrachna canadensis Marshall, 1929 – valid
  Hydrachna conjecta Koenike, 1895 – valid
  Hydrachna crenulata Marshall, 1930 – valid
  Hydrachna cruenta Muller, 1776 – valid
  Hydrachna cruenta cruenta Muller, 1776 – valid
  Hydrachna cruenta diminuata – valid
  Hydrachna geographica Muller, 1776 – valid
  Hydrachna geographica americana Lundblad, 1934 – valid
  Hydrachna geographica geographica Muller, 1776 – valid
  Hydrachna hesperia Lundblad, 1934 – valid
  Hydrachna hungerfordi Lundblad, 1934 – valid
  Hydrachna hutchinsoni Lundblad, 1934 – valid
  Hydrachna leegei Koenike – valid
  Hydrachna magniscutata Marshall, 1927 – valid
  Hydrachna marshallae Lundblad, 1934 – valid
  Hydrachna microscutata Marshall, 1929 – valid
  Hydrachna miliaria Berlese, 1888 – valid
  Hydrachna mystomirabilis Habeed, 1954 – valid
  Hydrachna rotunda Marshall, 1930 – valid
  Hydrachna stipata Lundblad, 1934 – valid
  Hydrachnidae – valid
  Hydrachnoidea – valid
  Hydractinia Van Beneden, 1841 – valid
  Hydractinia aggregata Fraser, 1911 – valid
  Hydractinia allmani – valid
  Hydractinia americana (Edwards, 1972) – valid
  Hydractinia arge (Clarke, 1882) – valid
  Hydractinia armata Fraser, 1940 – valid
  Hydractinia californica Torrey, 1904 – valid
  Hydractinia carica Bergh, 1887 – valid
  Hydractinia carnea (M. Sars, 1846) – valid
  Hydractinia carolinae Fraser, 1912 – valid
  Hydractinia dubia (Mayer, 1900) – valid
  Hydractinia echinata (Fleming, 1828) – valid – snailfur, snailfur
  Hydractinia fucicola (M. Sars, 1846) – valid
  Hydractinia hooperi (Sigerfoos, 1899) – invalid
  Hydractinia hooperii (Sigerfoos, 1899) – valid
  Hydractinia laevispina Fraser, 1922 – valid
  Hydractinia milleri Torrey, 1902 – valid – Miller hydractinia, miller hydractinia
  Hydractinia minima (Trinci, 1903) – valid
  Hydractinia minuta (Mayer, 1900) – valid
  Hydractinia monocarpa Allman, 1874 – valid
  Hydractinia multispina Fraser, 1938 – valid
  Hydractinia parvispina Hartlaub, 1905 – valid
  Hydractinia polycarpa Fraser, 1938 – valid
  Hydractinia polyclina L. Agassiz, 1862 – valid
  Hydractinia prolifica Fraser, 1948 – valid
  Hydractinia pruvoti Motz-kossowska, 1905 – invalid
  Hydractinia selena (Mills, 1976) – valid
  Hydractinia symbiolongicarpus Buss and Yund, 1989 – valid
  Hydractinia symbiopollicaris Buss and Yund, 1989 – valid
  Hydractinia valens Fraser, 1941 – valid
  Hydractiniidae L. Agassiz, 1862 – valid
  Hydractinioidea Aggassiz, 1862 – invalid
  Hydraecia Guenée, 1841 – valid
  Hydraecia columbia (Barnes and Benjamin, 1924) – invalid
  Hydraecia immanis Guenée, 1852 – valid – Hop Vine Borer Moth
  Hydraecia intermedia (Barnes and Benjamin, 1924) – valid
  Hydraecia medialis Smith, 1892 – valid
  Hydraecia micacea (Esper, 1789) – valid – potato stem worm, perce-tige de la pomme de terre, potato stem borer
  Hydraecia obliqua Harvey, 1876 – valid
  Hydraecia pallescens Smith, 1899 – invalid
  Hydraecia perobliqua Hampson, 1910 – valid
  Hydraecia stramentosa Guenée, 1852 – valid
  Hydraecia ximena (Barnes and Benjamin, 1924) – invalid
  Hydraena Kugelann, 1794 – valid
  Hydraena abbasigili Jäch, 1988 – valid
  Hydraena abdita Orchymont, 1948 – valid
  Hydraena abyssinica Régimbart, 1905 – valid
  Hydraena accurata Orchymont, 1948 – valid
  Hydraena achaica Jäch, 1995 – valid
  Hydraena acumena Perkins, 2011 – valid
  Hydraena adelbertensis Perkins, 2011 – valid
  Hydraena adrastea Orchymont, 1948 – valid
  Hydraena aethaliensis Breit, 1917 – valid
  Hydraena affirmata Perkins, 2007 – valid
  Hydraena affusa Orchymont, 1936 – valid
  Hydraena africana Kuwert, 1888 – valid
  Hydraena akameku Perkins, 2011 – valid
  Hydraena akbesiana Audisio, De Biase and Jäch, 1993 – valid
  Hydraena albai Sáinz-Cantero, 1993 – valid
  Hydraena alberti Balfour-Browne, 1950 – valid
  Hydraena alcantarana Ienistea, 1985 – valid
  Hydraena algerina Kaddouri, 1992 – valid
  Hydraena alia Orchymont, 1934 – valid
  Hydraena aliciae Jäch and Díaz, 2005 – valid
  Hydraena allomorpha Lagar and Fresneda, 1990 – valid
  Hydraena alluaudi Régimbart, 1906 – valid
  Hydraena alpicola Pretner, 1931 – valid
  Hydraena altamirensis Díaz Pazos and Garrido Gonzalez, 1993 – valid
  Hydraena altapapua Perkins, 2011 – valid
  Hydraena alternata Perkins, 1980 – valid
  Hydraena alterra Perkins, 1980 – valid
  Hydraena alticola Skale and Jäch, 2008 – valid
  Hydraena altiphila Perkins, 2011 – valid
  Hydraena amazonica Perkins, 2011 – valid
  Hydraena ambiflagellata Zwick, 1977 – valid
  Hydraena ambigua Ganglbauer, 1901 – valid
  Hydraena ambiosina Perkins, 2007 – valid
  Hydraena ambra Perkins, 2011 – valid
  Hydraena ambripes Perkins, 2011 – valid
  Hydraena ambroides Perkins, 2011 – valid
  Hydraena americana Jäch, 1993 – valid
  Hydraena amidensis Jäch, 1988 – valid
  Hydraena ampla Perkins, 2011 – valid
  Hydraena anaphora Perkins, 1980 – valid
  Hydraena anatolica Janssens, 1963 – valid
  Hydraena ancylis Perkins, 1980 – valid
  Hydraena ancyrae Jäch, 1992 – valid
  Hydraena andalusa Lagar and Fresneda, 1990 – valid
  Hydraena andreinii Orchymont, 1934 – valid
  Hydraena angulicollis Notman, 1921 – valid
  Hydraena angulosa Mulsant, 1844 – valid
  Hydraena angustata Sturm, 1836 – valid
  Hydraena anisonycha Perkins, 1980 – valid
  Hydraena antaria Perkins, 2007 – valid
  Hydraena antiatlantica Jäch, Aguilera and Hernando, 1998 – valid
  Hydraena antiochena Jäch, 1988 – valid
  Hydraena apertista Perkins, 2011 – valid
  Hydraena apexa Perkins, 2011 – valid
  Hydraena appalachicola Perkins, 1980 – valid
  Hydraena appetita Perkins, 2007 – valid
  Hydraena aquila Perkins, 2011 – valid
  Hydraena arabica Balfour-Browne, 1951 – valid
  Hydraena arachthi Ferro and Jäch, 2000 – valid
  Hydraena arcta Perkins, 2007 – valid
  Hydraena arenicola Perkins, 1980 – valid
  Hydraena argutipes Perkins, 1980 – valid
  Hydraena ariana Janssens, 1962 – valid
  Hydraena arizonica Perkins, 1980 – valid
  Hydraena armata Reitter, 1880 – valid
  Hydraena armatura Perkins, 2014 – valid
  Hydraena armeniaca Janssens, 1968 – valid
  Hydraena armipalpis Jäch and Díaz, 2000 – valid
  Hydraena armipes Rey, 1886 – valid
  Hydraena aroensis (Ferro, 1991) – valid
  Hydraena arunensis Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena ascensa Perkins, 2007 – valid
  Hydraena assimilis Rey, 1885 – valid
  Hydraena ateneo Freitag, 2013 – valid
  Hydraena athertonica Perkins, 2007 – valid
  Hydraena atlantica Perkins, 1980 – invalid
  Hydraena atrata Desbrochers des Loges, 1891 – valid
  Hydraena atroscintilla Perkins, 2011 – valid
  Hydraena attaleiae Ferro, 1984 – valid
  Hydraena audisioi Jäch, 1992 – valid
  Hydraena aulaarta Perkins, 2011 – valid
  Hydraena aurita Jäch, 1988 – valid
  Hydraena australica Zwick, 1977 – valid
  Hydraena australula Perkins, 2007 – valid
  Hydraena austrobesa Perkins, 2011 – valid
  Hydraena avuncula Jäch, 1988 – valid
  Hydraena bacchusi Perkins, 2011 – valid
  Hydraena bactriana Janssens, 1962 – valid
  Hydraena bakriensis Skale and Jäch, 2011 – valid
  Hydraena balearica Orchymont, 1930 – valid
  Hydraena balfourbrownei Bameul, 1986 – valid
  Hydraena balkei Perkins, 2011 – valid
  Hydraena balli Orchymont, 1940 – valid
  Hydraena barbipes Zwick, 1977 – valid
  Hydraena barricula Perkins, 1980 – valid
  Hydraena barrosi Orchymont, 1934 – valid
  Hydraena bedeli Berthélemy, 1992 – valid
  Hydraena belgica Orchymont, 1930 – valid
  Hydraena beniensis Perkins, 2011 – valid
  Hydraena benjaminus Jäch and Díaz, 2006 – valid
  Hydraena bensae Ganglbauer, 1901 – valid
  Hydraena bergeri (Janssens, 1972) – valid
  Hydraena berthelemyana Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006 – valid
  Hydraena berthelemyi Lagar and Fresneda, 1990 – invalid
  Hydraena berytus Jäch, 1986 – valid
  Hydraena beyarslani Jäch, 1988 – valid
  Hydraena bicarina Perkins, 2014 – valid
  Hydraena bicarinova Perkins, 2011 – valid
  Hydraena bicolorata Jäch, 1997 – valid
  Hydraena bicuspidata Ganglbauer, 1901 – valid
  Hydraena bidefensa Perkins, 2007 – valid
  Hydraena bifunda Perkins, 2011 – valid
  Hydraena bihamata Champion, 1920 – valid
  Hydraena biimpressa Perkins, 2007 – valid
  Hydraena billi Zwick, 1977 – valid
  Hydraena bilobata Jäch and Díaz, 1998 – valid
  Hydraena biltoni Jäch and Díaz, 2012 – valid
  Hydraena bimagua Jäch, 1986 – valid
  Hydraena birendra Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena biseptosa Perkins, 2014 – valid
  Hydraena bispinosa Pu, 1951 – valid
  Hydraena bisulcata Rey, 1884 – valid
  Hydraena bitruncata Orchymont, 1934 – valid
  Hydraena bituberculata Perkins, 1980 – valid
  Hydraena biundulata Perkins, 2011 – valid
  Hydraena blackburni Zaitzev, 1908 – valid
  Hydraena bodemeyeri Jäch and Díaz, 2001 – valid
  Hydraena boetcheri Orchymont, 1932 – valid
  Hydraena bolivari Orchymont, 1936 – valid
  Hydraena boliviana Perkins, 2011 – valid
  Hydraena bononiensis Binaghi, 1960 – valid
  Hydraena borbonica Fairmaire, 1898 – valid
  Hydraena borbonica borbonica Fairmaire, 1898 – valid
  Hydraena borbonica ofella Balfour-Browne, 1958 – valid
  Hydraena bosnica Apfelbeck, 1909 – valid
  Hydraena brachymera Orchymont, 1936 – valid
  Hydraena bractea Perkins, 1980 – valid
  Hydraena bractoides Perkins, 1980 – valid
  Hydraena brahmin Perkins, 2011 – valid
  Hydraena breedlovei Perkins, 1980 – valid
  Hydraena brevis Sharp, 1882 – valid
  Hydraena britteni Joy, 1907 – valid
  Hydraena brittoni Zwick, 1977 – valid
  Hydraena bromleyae Jäch, 1986 – valid
  Hydraena browni Perkins, 1980 – valid
  Hydraena bubulla Perkins, 2011 – valid
  Hydraena bulgarica Breit, 1916 – valid
  Hydraena buloba Perkins, 2011 – valid
  Hydraena buquintana Perkins, 2011 – valid
  Hydraena buscintilla Perkins, 2011 – valid
  Hydraena busuanga Freitag and Jäch, 2007 – valid
  Hydraena calcarifera Janssens, 1959 – valid
  Hydraena californica Perkins, 1980 – valid
  Hydraena campbelli Perkins, 1980 – valid
  Hydraena canakcioglui Janssens, 1965 – valid
  Hydraena canakcioglui aydini Janssens, 1965 – valid
  Hydraena canakcioglui canakcioglui Janssens, 1965 – valid
  Hydraena canticacollis Perkins, 1980 – valid
  Hydraena capacis Perkins, 2007 – valid
  Hydraena capensis Perkins, 2014 – valid
  Hydraena capetribensis Perkins, 2007 – valid
  Hydraena cappadocica Jäch, 1988 – valid
  Hydraena caprivica Perkins, 2014 – valid
  Hydraena capta Orchymont, 1936 – valid
  Hydraena carbonaria Kiesenwetter, 1849 – valid
  Hydraena carica Jäch, 1988 – valid
  Hydraena carinocisiva Perkins, 2011 – valid
  Hydraena carinulata Rey, 1886 – valid
  Hydraena carmellita Perkins, 2011 – valid
  Hydraena carniolica Pretner, 1970 – valid
  Hydraena castanea Deane, 1937 – valid
  Hydraena castanescens Freitag and Jäch, 2007 – valid
  Hydraena cata Orchymont, 1936 – valid
  Hydraena catalonica Fresneda, Aguilera and Hernando, 1994 – valid
  Hydraena catherinae Bameul and Jäch, 2001 – valid
  Hydraena caucasica Kuwert, 1888 – valid
  Hydraena cavifrons Perkins, 2011 – valid
  Hydraena cephalleniaca Jäch, 1985 – valid
  Hydraena cervisophila Jäch, 1992 – valid
  Hydraena challeti Perkins, 2011 – valid
  Hydraena cheesmanae Perkins, 2011 – valid
  Hydraena chenae Pu, 1951 – valid
  Hydraena chersonesica Jäch, Díaz and Przewozny, 2007 – valid
  Hydraena cherylbarrae Perkins, 2011 – valid
  Hydraena chiapa Perkins, 1980 – valid
  Hydraena chiesai Janssens, 1965 – valid
  Hydraena chifengi Jäch and Díaz, 1999 – valid
  Hydraena chobauti Guillebeau, 1896 – valid
  Hydraena christinae Audisio, De Biase and Jäch, 1996 – valid
  Hydraena christoferi Jäch and Díaz, 2005 – valid
  Hydraena ciliciensis Jäch, 1988 – valid
  Hydraena circulata Perkins, 1980 – valid
  Hydraena cirrata Champion, 1920 – valid
  Hydraena cirratoides Janssens, 1980 – invalid
  Hydraena clarinis Perkins, 2011 – valid
  Hydraena claryi Jäch, 1994 – invalid
  Hydraena claudia Freitag and Jäch, 2007 – valid
  Hydraena clavicula Perkins, 2014 – valid
  Hydraena clavigera Zwick, 1977 – valid
  Hydraena clemens Jäch and Díaz, 2006 – valid
  Hydraena clinodorsa Perkins, 2011 – valid
  Hydraena clystera Perkins, 2011 – valid
  Hydraena cochabamba Perkins, 2011 – valid
  Hydraena colchica Janssens, 1963 – valid
  Hydraena colombiana Perkins, 1980 – valid
  Hydraena colorata Perkins, 2011 – valid
  Hydraena colymba Perkins, 1980 – valid
  Hydraena compressipilis Jäch and Díaz, 1998 – valid
  Hydraena concepcionica Perkins, 2011 – valid
  Hydraena concinna Orchymont, 1932 – valid
  Hydraena confluenta Perkins, 2011 – valid
  Hydraena confusa Pu, 1951 – valid
  Hydraena connexa Orchymont, 1932 – valid
  Hydraena converga Perkins, 2007 – valid
  Hydraena coomani Orchymont, 1932 – valid
  Hydraena cooperi Balfour-Browne, 1954 – valid
  Hydraena cooperoides Perkins, 2014 – valid
  Hydraena copulata Perkins, 2011 – valid
  Hydraena cordata Schaufuss, 1883 – valid
  Hydraena cordiformis Jäch and Díaz, 2000 – valid
  Hydraena cordispina Perkins, 2011 – valid
  Hydraena corinna Orchymont, 1936 – valid
  Hydraena cornelli Jäch and Díaz, 1998 – valid
  Hydraena corrugis Orchymont, 1934 – valid
  Hydraena coryleti Jäch, 1992 – valid
  Hydraena costiniceps Perkins, 1980 – valid
  Hydraena crepidoptera Jäch, 1992 – valid
  Hydraena cristatigena Jäch and Díaz, 2000 – valid
  Hydraena croatica Kuwert, 1888 – valid
  Hydraena cryptostoma Jäch, 1992 – valid
  Hydraena crystallina Perkins, 1980 – valid
  Hydraena cubista Perkins, 2007 – valid
  Hydraena cultrata Perkins, 2007 – valid
  Hydraena cunicula Perkins, 2011 – valid
  Hydraena cunninghamensis Perkins, 2007 – valid
  Hydraena curta Kiesenwetter, 1849 – valid
  Hydraena curtipalpis Jäch and Díaz, 1998 – valid
  Hydraena curvipes Jäch and Díaz, 2012 – valid
  Hydraena curvosa Perkins, 2011 – valid
  Hydraena cuspidicollis Perkins, 1980 – valid
  Hydraena cyclops Jäch and Díaz, 2000 – valid
  Hydraena cygnus Zwick, 1977 – valid
  Hydraena czernohorskyi Müller, 1911 – valid
  Hydraena d-concava Perkins, 2011 – valid
  Hydraena d-destina Perkins, 1980 – valid
  Hydraena dalmatina Ganglbauer, 1901 – valid
  Hydraena damascena Pic, 1910 – valid
  Hydraena dariensis Perkins, 2011 – valid
  Hydraena darwini Perkins, 2007 – valid
  Hydraena debeckeri (Janssens, 1972) – valid
  Hydraena decepta Perkins, 2011 – valid
  Hydraena decipiens Zwick, 1977 – valid
  Hydraena decolor Sainte-Claire Deville, 1903 – valid
  Hydraena decui Spangler, 1980 – valid
  Hydraena delia Balfour-Browne, 1978 – valid
  Hydraena deliquesca Perkins, 2007 – valid
  Hydraena delvasi Delgado and Collantes, 1996 – valid
  Hydraena densa Fauvel, 1883 – valid
  Hydraena dentipalpis Reitter, 1888 – valid
  Hydraena dentipes Germar, 1824 – valid
  Hydraena devillei Ganglbauer, 1901 – valid
  Hydraena devincta Orchymont, 1940 – valid
  Hydraena diadema Perkins, 2011 – valid
  Hydraena diazi Trizzino, Jäch and Ribera in Trizzino, Jäch, Audisio and Rivera, 2011 – valid
  Hydraena diffusa Perkins, 2011 – valid
  Hydraena dilutipes Fairmaire, 1898 – valid
  Hydraena dimorpha Orchymont, 1922 – valid
  Hydraena dinosaurophila Jäch, 1994 – valid
  Hydraena discicollis Fairmaire, 1898 – valid
  Hydraena discreta Ganglbauer, 1904 – valid
  Hydraena disparamera Perkins, 2007 – valid
  Hydraena dochula Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena dolichogaster Janssens, 1965 – valid
  Hydraena dorrigoensis Perkins, 2007 – valid
  Hydraena draconisaurati Jäch and Díaz, 2005 – valid
  Hydraena dudgeoni Perkins, 2011 – valid
  Hydraena duodecimata Perkins, 2014 – valid
  Hydraena duohamata Perkins, 2011 – valid
  Hydraena ebriimadli Jäch, 1988 – valid
  Hydraena ecuadormica Perkins, 2011 – valid
  Hydraena egoni Jäch, 1986 – valid
  Hydraena eichleri Orchymont, 1937 – valid
  Hydraena einsteini Perkins, 2011 – valid
  Hydraena elephanta Perkins, 2014 – valid
  Hydraena elisabethae Jäch, 1992 – valid
  Hydraena eliya Jäch, 1982 – valid
  Hydraena emarginata Rey, 1885 – valid
  Hydraena emineae Jäch and Kasapoglu, 2006 – valid
  Hydraena epeirosi Ferro, 1985 – valid
  Hydraena errina Orchymont, 1948 – valid
  Hydraena erythraea Régimbart, 1905 – valid
  Hydraena eryx Orchymont, 1948 – valid
  Hydraena esquinita Brojer and Jäch, 2011 – valid
  Hydraena essentia Perkins, 2011 – valid
  Hydraena eucnemis Janssens, 1970 – valid
  Hydraena evanescens Rey, 1884 – valid
  Hydraena evansi Balfour-Browne, 1945 – valid
  Hydraena exarata Kiesenwetter, 1866 – valid
  Hydraena exasperata Orchymont, 1935 – valid
  Hydraena excisa Kiesenwetter, 1849 – valid
  Hydraena exhalista Perkins, 2011 – valid
  Hydraena exilipes Perkins, 1980 – valid
  Hydraena expedita Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena explanata Pic, 1905 – valid
  Hydraena extorris Zwick, 1977 – valid
  Hydraena falcata Jäch, 1992 – valid
  Hydraena farsensis Skale and Jäch, 2011 – valid
  Hydraena fasciata Perkins, 2011 – valid
  Hydraena fascinata Perkins, 2011 – valid
  Hydraena fasciola Perkins, 2011 – valid
  Hydraena fasciolata Perkins, 2011 – valid
  Hydraena fasciopaca Perkins, 2011 – valid
  Hydraena favulosa Perkins, 2014 – valid
  Hydraena fenestella Perkins, 2011 – valid
  Hydraena ferethula Perkins, 2007 – valid
  Hydraena feryi Skale and Jäch, 2011 – valid
  Hydraena feuerborni Orchymont, 1932 – valid
  Hydraena fijiensis Balfour-Browne, 1945 – valid
  Hydraena filum Sahlberg, 1908 – valid
  Hydraena finita Orchymont, 1943 – valid
  Hydraena finki Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena finniganensis Perkins, 2007 – valid
  Hydraena fiorii Porta, 1899 – valid
  Hydraena fischeri Schönmann, 1991 – valid
  Hydraena flagella Perkins, 2011 – valid
  Hydraena flavipes Sturm, 1836 – invalid
  Hydraena fluvicola (Perkins, 1980) – valid
  Hydraena foliobba Perkins, 2011 – valid
  Hydraena fontana Orchymont, 1932 – valid
  Hydraena fontiscarsavii (Jäch, 1988) – valid
  Hydraena formosapala Perkins, 2011 – valid
  Hydraena formula Orchymont, 1932 – valid
  Hydraena forticollis Perkins, 2007 – valid
  Hydraena fosterorum Trizzino, Jäch and Ribera in Trizzino, Jäch, Audisio and Rivera, 2011 – valid
  Hydraena franklyni Deler-Hernández and Delgado, 2012 – valid
  Hydraena freitagi Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena frenzeli Skale and Jäch, 2008 – valid
  Hydraena fritzi Jäch, 1992 – valid
  Hydraena frondsicola (Perkins, 1980) – valid
  Hydraena funda Perkins, 2011 – valid
  Hydraena fundacta Perkins, 2011 – valid
  Hydraena fundaequalis Perkins, 2007 – valid
  Hydraena fundapta Perkins, 2011 – valid
  Hydraena fundarca Perkins, 2011 – valid
  Hydraena fundata Perkins, 2007 – valid
  Hydraena fundextra Perkins, 2011 – valid
  Hydraena furthi Jäch, 1982 – valid
  Hydraena gaditana Lagar and Fresneda, 1990 – valid
  Hydraena galatica Janssens, 1970 – valid
  Hydraena galea Perkins, 2011 – valid
  Hydraena gavarrensis Jäch, Díaz and Martinoy, 2005 – valid
  Hydraena geminya Perkins, 1980 – valid
  Hydraena genumorpha Perkins, 2014 – valid
  Hydraena georgiadesi Orchymont, 1931 – valid
  Hydraena geraldneuhauseri Jäch and Díaz, 2006 – valid
  Hydraena germaini Orchymont, 1923 – valid
  Hydraena glassmani Jäch, 1986 – valid
  Hydraena gnatella Orchymont, 1945 – valid
  Hydraena gnatelloides Orchymont, 1945 – valid
  Hydraena gracilidelphis Trizzino, Valladares, Garrido and Audisio, 2012 – valid
  Hydraena gracilis Germar, 1824 – valid
  Hydraena gracilis balcanica Orchymont, 1930 – valid
  Hydraena gracilis gracilis Germar, 1824 – valid
  Hydraena graciloides (Jäch, 1988) – valid
  Hydraena grandis Reitter, 1885 – valid
  Hydraena graphica Orchymont, 1931 – valid
  Hydraena grata Orchymont, 1944 – valid
  Hydraena gregalis Orchymont, 1944 – valid
  Hydraena gressa Orchymont, 1944 – valid
  Hydraena griphus Orchymont, 1944 – valid
  Hydraena grouvellei Orchymont, 1923 – valid
  Hydraena grueberi Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena guadelupensis Orchymont, 1923 – valid
  Hydraena guangxiensis Jäch and Díaz, 2005 – valid
  Hydraena guatemala Perkins, 1980 – valid
  Hydraena guentheri Jäch, 1992 – valid
  Hydraena guilin Jäch and Díaz, 2005 – valid
  Hydraena gynaephila Jäch, 1997 – valid
  Hydraena habitiva Perkins, 2014 – valid
  Hydraena hainzi Jäch, 1988 – valid
  Hydraena haitensis Perkins, 1980 – valid
  Hydraena hajeki Skale and Jäch, 2011 – valid
  Hydraena hamifera Zwick, 1977 – valid
  Hydraena hansreuteri Jäch and Díaz, 2005 – valid
  Hydraena hayashii Jäch and Díaz, 2012 – valid
  Hydraena helena Orchymont, 1929 – valid
  Hydraena hendrichi Jäch, Díaz and Skale, 2013 – valid
  Hydraena hernandoi Fresneda and Lagar, 1990 – valid
  Hydraena herzogestella Perkins, 2011 – valid
  Hydraena heterogyna Bedel, 1898 – valid
  Hydraena heterogyna binaghii Jäch, 1989 – valid
  Hydraena heterogyna doderoi Ganglbauer, 1901 – valid
  Hydraena heterogyna heterogyna Bedel, 1898 – valid
  Hydraena heterogyna italica Ganglbauer, 1901 – valid
  Hydraena hiekei Jäch, 1992 – valid
  Hydraena hillaryi Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena hintoni Perkins, 2011 – valid
  Hydraena hispanica Ganglbauer, 1901 – valid
  Hydraena holdhausi Pretner, 1929 – valid
  Hydraena hornabrooki Perkins, 2011 – valid
  Hydraena hortensis Jäch and Díaz, 2000 – valid
  Hydraena hosiwergi Freitag and Jäch, 2007 – valid
  Hydraena hosseinieorum Bilton and Jäch, 1998 – valid
  Hydraena huangshanensis Jäch and Díaz, 2005 – valid
  Hydraena huitongensis Jäch and Díaz, 2005 – valid
  Hydraena humanica Perkins, 2014 – valid
  Hydraena hunanensis Pu, 1951 – valid
  Hydraena hungarica Rey, 1884 – valid
  Hydraena huonica Perkins, 2011 – valid
  Hydraena hyalina Perkins, 1980 – valid
  Hydraena hynesi Zwick, 1977 – valid
  Hydraena hypipamee Perkins, 2007 – valid
  Hydraena ibalimi Perkins, 2011 – valid
  Hydraena iberica Orchymont, 1936 – valid
  Hydraena idema Perkins, 2011 – valid
  Hydraena iheya Jäch and Díaz, 1999 – valid
  Hydraena ilamensis Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena ilica Jäch, 1994 – valid
  Hydraena imbria Jäch and Díaz, 2001 – valid
  Hydraena impala Perkins, 2011 – valid
  Hydraena imperatrix Kniz, 1919 – valid
  Hydraena impercepta Zwick, 1977 – valid
  Hydraena impressicollis Fairmaire, 1898 – valid
  Hydraena inancala Perkins, 2007 – valid
  Hydraena inapicipalpis Pic, 1918 – valid
  Hydraena incisiva Perkins, 2011 – valid
  Hydraena incista Perkins, 2011 – valid
  Hydraena incurva Orchymont, 1932 – valid
  Hydraena indiana Jäch, 1994 – valid
  Hydraena indica Orchymont, 1920 – valid
  Hydraena infoveola Perkins, 2011 – valid
  Hydraena ingens (Perkins, 1980) – valid
  Hydraena inhalista Perkins, 2011 – valid
  Hydraena injectiva Perkins, 2014 – valid
  Hydraena innuda Perkins, 2007 – valid
  Hydraena inopinata Jäch and Díaz, 1998 – valid
  Hydraena inplacopaca Perkins, 2011 – valid
  Hydraena insandalia Perkins, 2011 – valid
  Hydraena insita Orchymont, 1932 – valid
  Hydraena insolita Orchymont, 1932 – valid
  Hydraena insularis Orchymont, 1945 – valid
  Hydraena integra Pretner, 1931 – valid
  Hydraena intensa Perkins, 2011 – valid
  Hydraena intermedia Rosenhauer, 1847 – valid
  Hydraena intraangulata Perkins, 2007 – valid
  Hydraena inusta Orchymont, 1932 – valid
  Hydraena invicta Perkins, 2007 – valid
  Hydraena iriomotensis Jäch and Díaz, 1999 – valid
  Hydraena isabelae Castro and Herrera, 2001 – valid
  Hydraena isolinae Jäch and Díaz, 1998 – valid
  Hydraena ispirensis Kasapoglu, Jäch and Skale, 2010 – valid
  Hydraena iterata Orchymont, 1948 – valid
  Hydraena jacobsoni Orchymont, 1932 – valid
  Hydraena jaechiana (Audisio and De Biase, 1990) – valid
  Hydraena jaegeri Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena jailensis Breit, 1917 – valid
  Hydraena janczyki Jäch, 1992 – valid
  Hydraena janeceki Jäch, 1987 – valid
  Hydraena janssensi Nilsson, 2001 – valid
  Hydraena jengi Jäch and Díaz, 1998 – valid
  Hydraena jilanzhui Jäch and Díaz, 2005 – valid
  Hydraena jivaro Perkins, 1980 – valid
  Hydraena johncoltranei Perkins, 2011 – valid
  Hydraena jubilata Perkins, 2011 – valid
  Hydraena kadowakii Jäch and Díaz, 2012 – valid
  Hydraena kakadu Perkins, 2007 – valid
  Hydraena kamitei Jäch and Díaz, 2012 – valid
  Hydraena karinkukolae Jäch, 1989 – valid
  Hydraena karmai Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena kasyi Jäch, 1992 – valid
  Hydraena kaufmanni Ganglbauer, 1901 – valid
  Hydraena kellymilleri Perkins, 2011 – valid
  Hydraena khnzoriani Janssens, 1968 – valid
  Hydraena kilimandjarensis Régimbart, 1906 – valid
  Hydraena kitayamai Jäch and Díaz, 2012 – valid
  Hydraena knischi Orchymont, 1928 – valid
  Hydraena kocheri Berthélemy, 1992 – valid
  Hydraena kodadai Freitag and Jäch, 2007 – valid
  Hydraena koje Perkins, 2011 – valid
  Hydraena koma Perkins, 2011 – valid
  Hydraena krasnodarensis Jäch and Díaz, 2006 – valid
  Hydraena kroumiriana Kaddouri, 1992 – valid
  Hydraena kucinici Micetic Stankovic and Jäch, 2012 – valid
  Hydraena kuehnelti Jäch, 1989 – valid
  Hydraena kurdistanica Jäch, 1988 – valid
  Hydraena kwangsiensis Pu, 1951 – valid
  Hydraena labropaca Perkins, 2011 – valid
  Hydraena lagamba Brojer and Jäch, 2011 – valid
  Hydraena lapidicola Kiesenwetter, 1849 – valid
  Hydraena lapissectilis Jäch, 1992 – valid
  Hydraena larissae Jäch and Díaz, 2000 – valid
  Hydraena larsoni Perkins, 2007 – valid
  Hydraena lascrucensis Brojer and Jäch, 2011 – valid
  Hydraena lassulipes Perkins, 2011 – valid
  Hydraena latebricola Jäch, 1986 – valid
  Hydraena latisoror Perkins, 2007 – valid
  Hydraena lazica Janssens, 1963 – valid
  Hydraena leechi Perkins, 1980 – valid
  Hydraena leei Jäch and Díaz, 1998 – valid
  Hydraena legorskyi Jäch and Brojer, 2012 – valid
  Hydraena lehmanni Jäch and Díaz, 2005 – valid
  Hydraena leonhardi Breit, 1916 – valid
  Hydraena leprieuri Sainte-Claire Deville, 1905 – valid
  Hydraena levantina Sahlberg, 1908 – valid
  Hydraena ligulipes Jäch, 1988 – valid
  Hydraena lilianae Perkins, 2011 – valid
  Hydraena limbobesa Perkins, 2011 – valid
  Hydraena limpidicollis Perkins, 1980 – valid
  Hydraena liriope Orchymont, 1943 – valid
  Hydraena longicollis Sharp, 1882 – valid
  Hydraena loripes Perkins, 2011 – valid
  Hydraena lotti Bilton, 2013 – valid
  Hydraena lucasi Lagar, 1984 – valid
  Hydraena lucernae Zwick, 1977 – valid
  Hydraena ludovicae Orchymont, 1931 – valid
  Hydraena luminicollis Perkins, 2007 – valid
  Hydraena luridipennis MacLeay, 1873 – valid
  Hydraena lusitana (Berthélemy in Berthélemy and Whytton Da Terra, 1977) – valid
  Hydraena lycia Jäch, 1988 – valid
  Hydraena macedonica Orchymont, 1931 – valid
  Hydraena maculicollis Champion, 1920 – valid
  Hydraena maculopala Perkins, 2011 – valid
  Hydraena madronensis Castor, García and Ferreras, 2000 – valid
  Hydraena magna Pu, 1951 – valid
  Hydraena magnessa Jäch, 1997 – valid
  Hydraena magnetica Zwick, 1977 – valid
  Hydraena mahensis Scott, 1913 – valid
  Hydraena malagricola Jäch and Díaz, 2012 – valid
  Hydraena malickyi Jäch, 1989 – valid
  Hydraena malkini Perkins, 1980 – valid
  Hydraena manabica Perkins, 2011 – valid
  Hydraena manaslu Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena manfredjaechi Delgado and Soler, 1991 – valid
  Hydraena manguao Freitag and Jäch, 2007 – valid
  Hydraena manulea Perkins, 2011 – valid
  Hydraena manuloides Perkins, 2011 – valid
  Hydraena marawaka Perkins, 2011 – valid
  Hydraena marcosae Aguilera, Hernando and Ribera, 1997 – valid
  Hydraena marginicollis Kiesenwetter, 1849 – valid
  Hydraena mariannae Jäch, 1992 – valid
  Hydraena marinae Castro, 2003 – valid
  Hydraena maroccana Kaddouri, 1992 – invalid
  Hydraena martensi Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena martinschoepfi Jäch and Díaz, 2005 – valid
  Hydraena masatakai Jäch and Díaz, 2003 – valid
  Hydraena maureenae Perkins, 1980 – valid
  Hydraena mauriciogarciai Perkins, 2011 – valid
  Hydraena mazamitla Perkins, 1980 – valid
  Hydraena mecai Millán and Aguilera, 2000 – valid
  Hydraena melas Dalla Torre, 1877 – valid
  Hydraena mercuriala Perkins, 2011 – valid
  Hydraena meschniggi Pretner, 1929 – valid
  Hydraena metzeni Perkins, 2007 – valid
  Hydraena mexicana Perkins, 1980 – valid
  Hydraena mianminica Perkins, 2011 – valid
  Hydraena michaelbalkei Jäch, Díaz and Skale, 2013 – valid
  Hydraena mignymixys Perkins, 1980 – valid
  Hydraena millerorum Perkins, 2007 – valid
  Hydraena miniretia Perkins, 2007 – valid
  Hydraena mintrita Perkins, 2011 – valid
  Hydraena mitchellensis Perkins, 2007 – valid
  Hydraena miyatakei Satô, 1959 – valid
  Hydraena modili Jäch, 1988 – valid
  Hydraena monikae Jäch and Díaz, 2000 – valid
  Hydraena monscassius Jäch, 1988 – valid
  Hydraena monstruosipes Ferro, 1986 – valid
  Hydraena monteithi Perkins, 2007 – valid
  Hydraena morio Kiesenwetter, 1849 – valid
  Hydraena motzfeldi Skale and Jäch, 2011 – valid
  Hydraena mouzaiensis Sainte-Claire Deville, 1909 – valid
  Hydraena mpumalanga Perkins, 2014 – valid
  Hydraena muelleri Pretner, 1931 – valid
  Hydraena muezziginea Jäch, 1988 – valid
  Hydraena multiloba Perkins, 2011 – valid
  Hydraena multimurata Perkins, 2014 – valid
  Hydraena multispina Perkins, 2011 – valid
  Hydraena mylasae Jäch, 1992 – valid
  Hydraena myrmidon Janssens, 1960 – invalid
  Hydraena namibiensis Perkins, 2014 – valid
  Hydraena nanocolorata Perkins, 2011 – valid
  Hydraena nanopala Perkins, 2011 – valid
  Hydraena nanoscintilla Perkins, 2011 – valid
  Hydraena natiforma Perkins, 2014 – valid
  Hydraena neblina Perkins, 2011 – valid
  Hydraena needhami Orchymont, 1929 – invalid
  Hydraena nelsonmandelai Makhan, 2008 – valid
  Hydraena neoaccurata Perkins, 2014 – valid
  Hydraena nevermanni Perkins, 1980 – valid
  Hydraena newtoni Perkins, 1980 – valid
  Hydraena nielshaggei Freitag and Jäch, 2007 – valid
  Hydraena niger Hatch, 1965 – invalid
  Hydraena nigra Hatch, 1965 – valid
  Hydraena nigrita Germar, 1824 – valid
  Hydraena nike Jäch, 1995 – valid
  Hydraena nilguenae (Jäch, 1988) – valid
  Hydraena nitidimenta Perkins, 2011 – valid
  Hydraena nivalis Jäch, 1992 – valid
  Hydraena nomenipes Perkins, 2014 – valid
  Hydraena notsui Satô, 1978 – valid
  Hydraena novacula Perkins, 2011 – valid
  Hydraena numidica Sainte-Claire Deville, 1905 – valid
  Hydraena nurabadensis Skale and Jäch, 2011 – valid
  Hydraena nuratauensis Jäch, 1994 – valid
  Hydraena oaxaca Perkins, 1980 – valid
  Hydraena oblio Perkins, 1980 – valid
  Hydraena occidentalis Perkins, 1980 – valid
  Hydraena occitana (Audisio and De Biase, 1995) – valid
  Hydraena okapa Perkins, 2011 – valid
  Hydraena okinawensis Jäch and Díaz, 1999 – valid
  Hydraena olidipastoris Jäch, 1988 – valid
  Hydraena ollopa Perkins, 2011 – valid
  Hydraena optica Jäch and Díaz, 2012 – valid
  Hydraena orchis Jäch and Díaz, 1998 – valid
  Hydraena orcula Perkins, 1980 – valid
  Hydraena ordishi Delgado and Palma, 1997 – valid
  Hydraena orientalis Breit, 1916 – valid
  Hydraena ortali Jäch, 1986 – valid
  Hydraena orthosia Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006 – valid
  Hydraena otiarca Perkins, 2011 – valid
  Hydraena ovata Janssens, 1961 – valid
  Hydraena owenobesa Perkins, 2011 – valid
  Hydraena oxiana Janssens, 1974 – valid
  Hydraena ozarkensis Perkins, 1980 – valid
  Hydraena pachyptera Apfelbeck, 1909 – valid
  Hydraena pacifica Perkins, 1980 – valid
  Hydraena pacificica Perkins, 2011 – valid
  Hydraena paeminosa Perkins, 1980 – valid
  Hydraena pagaluensis Hernando and Ribera, 2001 – valid
  Hydraena paganettii Ganglbauer, 1901 – valid
  Hydraena pajarita Brojer and Jäch, 2011 – valid
  Hydraena pakistanica Jäch, 1992 – valid
  Hydraena pala Perkins, 2011 – valid
  Hydraena palamita Perkins, 2011 – valid
  Hydraena palawanensis Freitag and Jäch, 2007 – valid
  Hydraena pallidula Sainte-Claire Deville, 1909 – valid
  Hydraena palustris Erichson, 1837 – valid
  Hydraena pamirica Jäch, 1992 – valid
  Hydraena pamphylia Jäch and Díaz, 2001 – valid
  Hydraena pangaei Jäch, 1992 – valid
  Hydraena pantanalensis Perkins, 2011 – valid
  Hydraena paraguayensis Janssens, 1972 – valid
  Hydraena parciplumea Perkins, 2007 – valid
  Hydraena particeps Perkins, 1980 – valid
  Hydraena parva Zwick, 1977 – valid
  Hydraena parysatis Janssens, 1981 – valid
  Hydraena paucistriata Jäch and Díaz, 2000 – valid
  Hydraena paulmoritz Jäch, Díaz and Skale, 2013 – valid
  Hydraena pavicula Perkins, 1980 – valid
  Hydraena paxillipes Perkins, 2011 – valid
  Hydraena peckorum Perkins, 2011 – valid
  Hydraena pectenata Perkins, 2011 – valid
  Hydraena pedroaguilerai Perkins, 2011 – valid
  Hydraena pegopyga Perkins, 2011 – valid
  Hydraena pelops Jäch, 1995 – valid
  Hydraena pennsylvanica Kiesenwetter, 1849 – invalid
  Hydraena pensylvanica Kiesenwetter, 1849 – valid
  Hydraena penultimata Perkins, 2011 – valid
  Hydraena perkinsi Spangler, 1980 – valid
  Hydraena perlonga Balfour-Browne, 1950 – valid
  Hydraena perpunctata Perkins, 2011 – valid
  Hydraena persica Janssens, 1981 – valid
  Hydraena pertransversa Perkins, 2011 – valid
  Hydraena peru Perkins, 1980 – valid
  Hydraena pesici Skale and Jäch, 2011 – valid
  Hydraena petila Perkins, 1980 – valid
  Hydraena phainops Perkins, 2011 – valid
  Hydraena phallerata Orchymont, 1944 – valid
  Hydraena phallica Orchymont, 1930 – valid
  Hydraena phassilyi Orchymont, 1931 – valid
  Hydraena philippi Jäch and Díaz, 2005 – valid
  Hydraena philyra Orchymont, 1944 – valid
  Hydraena phoenicia Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006 – valid
  Hydraena photogenica Perkins, 2011 – valid
  Hydraena pici Sainte-Claire Deville, 1905 – valid
  Hydraena picula Perkins, 2011 – valid
  Hydraena pilimera Brojer and Jäch, 2011 – valid
  Hydraena pilipes Zwick, 1977 – valid
  Hydraena pilulambra Perkins, 2011 – valid
  Hydraena pindica Janssens, 1965 – valid
  Hydraena pisciforma Perkins, 2014 – valid
  Hydraena planata Kiesenwetter, 1849 – valid
  Hydraena plastica Orchymont, 1943 – valid
  Hydraena plastica plastica Orchymont, 1943 – invalid
  Hydraena plastica terraevastatae Jäch, 1988 – invalid
  Hydraena platycnemis Jäch, 1988 – valid
  Hydraena platynaspis Jäch, 1988 – valid
  Hydraena platysoma Janssens, 1968 – valid
  Hydraena plaumanni Orchymont, 1937 – valid
  Hydraena plumipes Rey, 1886 – valid
  Hydraena pluralticola Perkins, 2011 – valid
  Hydraena plurifurcata Jäch and Díaz, 1998 – valid
  Hydraena polita Kiesenwetter, 1849 – valid
  Hydraena pontequula Perkins, 1980 – valid
  Hydraena pontica Janssens, 1963 – valid
  Hydraena porchi Perkins, 2007 – valid
  Hydraena porcula Jäch and Díaz, 1998 – valid
  Hydraena praetermissa Jäch, 1987 – valid
  Hydraena premordica Perkins, 1980 – valid
  Hydraena pretneri Chiesa, 1927 – valid
  Hydraena prieto Perkins, 1980 – valid
  Hydraena princeps Fauvel, 1903 – valid
  Hydraena processa Perkins, 2011 – valid
  Hydraena producta Mulsant and Rey, 1852 – valid
  Hydraena proesei Skale and Jäch, 2011 – valid
  Hydraena profunda Perkins, 2014 – valid
  Hydraena prokini Jäch and Díaz, 2006 – valid
  Hydraena propria Perkins, 2011 – valid
  Hydraena prusensis Jäch, 1992 – valid
  Hydraena pseudocirrata Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena pseudopalawanensis Freitag and Jäch, 2007 – valid
  Hydraena pseudoriparia Orchymont, 1945 – valid
  Hydraena puetzi Jäch, 1994 – valid
  Hydraena pugillista Perkins, 2007 – valid
  Hydraena pulchella Germar, 1824 – valid
  Hydraena pulsatrix Perkins, 1980 – valid
  Hydraena punctata LeConte, 1855 – valid
  Hydraena puncticollis Sharp, 1882 – valid
  Hydraena punctilata Perkins, 2011 – valid
  Hydraena putearius Jäch and Díaz, 2000 – valid
  Hydraena pygmaea Waterhouse, 1833 – valid
  Hydraena pygmaea pygmaea Waterhouse, 1833 – valid
  Hydraena pygmaea reflexa Rey, 1884 – valid
  Hydraena quadrata (Janssens, 1980) – valid
  Hydraena quadricollis Wollaston, 1864 – valid
  Hydraena quadricurvipes Perkins, 1980 – valid
  Hydraena quadriplumipes Perkins, 2011 – valid
  Hydraena quechua Perkins, 1980 – valid
  Hydraena queenslandica Perkins, 2007 – valid
  Hydraena quetiae Castro, 2000 – valid
  Hydraena quilisi Lagar, Fresneda and Fernando, 1987 – valid
  Hydraena quintana Perkins, 2011 – valid
  Hydraena ramuensis Perkins, 2011 – valid
  Hydraena ramuquintana Perez, 2011 – valid
  Hydraena receptiva Perkins, 2011 – valid
  Hydraena reflectiva Perkins, 2014 – valid
  Hydraena regimbarti Zaitzev, 1908 – valid
  Hydraena remulipes Perkins, 2011 – valid
  Hydraena reticulata Zwick, 1977 – valid
  Hydraena reticuloides Perkins, 2007 – valid
  Hydraena reticulositis Perkins, 2007 – valid
  Hydraena revelovela Perkins, 2007 – valid
  Hydraena reverberata Perkins, 2011 – valid
  Hydraena reyi Kuwert, 1888 – valid
  Hydraena rhinoceros (Janssens, 1972) – valid
  Hydraena rhodia Jäch, 1985 – valid
  Hydraena riberai Jäch, Aguilera and Hernando, 1998 – valid
  Hydraena richardimbi Jäch, 1992 – valid
  Hydraena rigua Orchymont, 1931 – valid
  Hydraena ripaeaureae (Janssens, 1972) – valid
  Hydraena riparia Kugelann, 1794 – valid
  Hydraena rivularis Guillebeau, 1896 – valid
  Hydraena robusta Zwick, 1977 – valid
  Hydraena rosannae Audisio, Trizzino and De Biase in Audisio, Trizzino, De Biase, Mancini and Antonini, 2009 – valid
  Hydraena rudallensis Blackburn, 1896 – valid
  Hydraena rufipennis Boscá Berga, 1932 – valid
  Hydraena rufipes Curtis, 1830 – valid
  Hydraena rugosa Mulsant, 1844 – valid
  Hydraena ruinosa Zwick, 1977 – valid
  Hydraena rukiyeae Kasapoglu, Jäch and Skale, 2010 – valid
  Hydraena sabella Perkins, 1980 – valid
  Hydraena saga Orchymont, 1930 – valid
  Hydraena sagatai Perkins, 2011 – valid
  Hydraena sahlbergi Orchymont, 1923 – valid
  Hydraena saluta Perkins, 2011 – valid
  Hydraena samia Jäch, 1986 – valid
  Hydraena samnitica Knisch, 1924 – valid
  Hydraena sanagergelyae Brojer and Jäch, 2011 – valid
  Hydraena sanfilippoi (Audisio and De Biase, 1995) – valid
  Hydraena sappho Janssens, 1965 – valid
  Hydraena sardoa Binaghi, 1961 – valid
  Hydraena satoi Jäch and Díaz, 1999 – valid
  Hydraena sautakei Jäch and Díaz, 1999 – valid
  Hydraena sauteri Orchymont, 1913 – valid
  Hydraena scabra Orchymont, 1925 – valid
  Hydraena scabrosa Orchymont, 1931 – valid
  Hydraena schawalleri Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena schilfii Jäch, 1988 – valid
  Hydraena schillhammeri Jäch, 1988 – valid
  Hydraena schmidi Jäch and Díaz, 2001 – valid
  Hydraena schoedli Jäch, 1992 – valid
  Hydraena schoenmanni Jäch, 1988 – valid
  Hydraena schubertorum Jäch and Díaz, 2001 – valid
  Hydraena schuelkei Jäch, 1992 – valid
  Hydraena schuleri Ganglbauer, 1901 – valid
  Hydraena scintilla Perkins, 1980 – valid
  Hydraena scintillabella Perkins, 1980 – valid
  Hydraena scintillamima Perkins, 2011 – valid
  Hydraena scintillapicta Perkins, 2011 – valid
  Hydraena scintillarca Perkins, 2011 – valid
  Hydraena scintillutea Perkins, 1980 – valid
  Hydraena scitula Orchymont, 1943 – valid
  Hydraena scitula gynaephila Jäch, 1997 – valid
  Hydraena scitula scitula Orchymont, 1943 – valid
  Hydraena scolops Perkins, 1980 – valid
  Hydraena scopula Perkins, 1980 – valid
  Hydraena scythica Janssens, 1974 – valid
  Hydraena sebastiani Perkins, 2014 – valid
  Hydraena sepikramuensis Perkins, 2011 – valid
  Hydraena septemlacuum Jäch, 1992 – valid
  Hydraena septemlacuum septemlacuum Jäch, 1992 – invalid
  Hydraena septemlacuum sinope Jäch, 1992 – invalid
  Hydraena serpentina Jäch, 1988 – valid
  Hydraena serricollis Wollaston, 1864 – valid
  Hydraena servilia Orchymont, 1936 – valid
  Hydraena sexarcuata Perkins, 2011 – valid
  Hydraena sexsuprema Perkins, 2011 – valid
  Hydraena sharmai Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena sharpi Rey, 1886 – valid
  Hydraena shorti Perkins, 2011 – valid
  Hydraena sicula Kiesenwetter, 1849 – valid
  Hydraena sidon Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006 – valid
  Hydraena sierra Perkins, 1980 – valid
  Hydraena similis Orchymont, 1930 – valid
  Hydraena simonidea Orchymont, 1931 – valid
  Hydraena simplicicollis Blackburn, 1896 – valid
  Hydraena simplipes Zwick, 1977 – valid
  Hydraena singaporensis Jäch, Díaz and Skale, 2013 – valid
  Hydraena sinope Jäch, 1992 – valid
  Hydraena smyrnensis Sahlberg, 1908 – valid
  Hydraena socius Jäch and Díaz, 1999 – valid
  Hydraena solarii Pretner, 1930 – valid
  Hydraena solodovnikovi Jäch and Díaz, 2006 – valid
  Hydraena sordida Sharp, 1882 – valid
  Hydraena spangleri Perkins, 1980 – valid
  Hydraena spatula Perkins, 2011 – valid
  Hydraena speciosa Orchymont, 1944 – valid
  Hydraena spinipes Baudi, 1882 – valid
  Hydraena spinissima Perkins, 2007 – valid
  Hydraena spinobesa Perkins, 2011 – valid
  Hydraena splecoma Perkins, 1980 – valid
  Hydraena squalida Orchymont, 1932 – valid
  Hydraena stefani Jäch and Díaz, 2005 – valid
  Hydraena steineri Perkins, 2011 – valid
  Hydraena stellula Perkins, 2011 – valid
  Hydraena storeyi Perkins, 2007 – valid
  Hydraena striolata Perkins, 2011 – valid
  Hydraena stussineri Kuwert, 1888 – valid
  Hydraena subacuminata Rey, 1884 – valid
  Hydraena subgrandis Jäch, 1988 – valid
  Hydraena subimpressa Rey, 1885 – valid
  Hydraena subina Orchymont, 1944 – valid
  Hydraena subinflata Orchymont, 1944 – valid
  Hydraena subinoides Orchymont, 1944 – valid
  Hydraena subintegra Ganglbauer, 1901 – valid
  Hydraena subintegra aroensis (Ferro, 1992) – valid
  Hydraena subintegra subintegra Ganglbauer, 1901 – valid
  Hydraena subinura Orchymont, 1944 – valid
  Hydraena subirregularis Pic, 1918 – valid
  Hydraena subjuncta Orchymont, 1930 – valid
  Hydraena sublamina Orchymont, 1945 – valid
  Hydraena sublapsa Orchymont, 1945 – valid
  Hydraena subsequens Rey, 1886 – valid
  Hydraena supersexa Perkins, 2011 – valid
  Hydraena supina Perkins, 2011 – valid
  Hydraena szechuanensis Pu, 1951 – valid
  Hydraena takin Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena takutu Perkins, 2011 – valid
  Hydraena tarsotricha Perkins, 2011 – valid
  Hydraena tarvisina (Ferro, 1992) – valid
  Hydraena tatii Sáinz-Cantero and Alba-Tercedor, 1989 – valid
  Hydraena tauricola Jäch, 1988 – valid
  Hydraena taxila Janssens, 1962 – valid
  Hydraena tekmanensis Jäch, Skale and Kasapoglu, 2011 – valid
  Hydraena tenjikuana Satô, 1979 – valid
  Hydraena tenuis (Janssens, 1980) – valid
  Hydraena tenuisella Perkins, 2007 – valid
  Hydraena tenuisoror Perkins, 2007 – valid
  Hydraena terebrans Jäch, 1992 – valid
  Hydraena terraevastatae Jäch, 1988 – invalid
  Hydraena terralta Perkins, 1980 – valid
  Hydraena testacea Curtis, 1830 – valid
  Hydraena tetana Perkins, 2011 – valid
  Hydraena textila Perkins, 2007 – valid
  Hydraena thienemanni Orchymont, 1932 – valid
  Hydraena thola Perkins, 2011 – valid
  Hydraena tholasoris Perkins, 2011 – valid
  Hydraena thumbelina Perkins, 2011 – valid
  Hydraena thumbelipes Perkins, 2011 – valid
  Hydraena thyene Balfour-Browne, 1958 – valid
  Hydraena tiara Perkins, 2014 – valid
  Hydraena tibiopaca Perkins, 2011 – valid
  Hydraena tobogan Perkins, 2011 – valid
  Hydraena torosopala Perkins, 2011 – valid
  Hydraena torricellica Perkins, 2011 – valid
  Hydraena transvallis Perkins, 2011 – valid
  Hydraena trapezoidalis Zwick, 1977 – valid
  Hydraena tricantha Zwick, 1977 – valid
  Hydraena trichotarsa Perkins, 2011 – valid
  Hydraena tricosipes Perkins, 2011 – valid
  Hydraena tridigita Perkins, 2011 – valid
  Hydraena tridisca Perkins, 2007 – valid
  Hydraena triloba Perkins, 2007 – valid
  Hydraena trinidensis Perkins, 1980 – valid
  Hydraena triparamera Jäch, 1982 – valid
  Hydraena tritropis Perkins, 2011 – valid
  Hydraena tritutela Perkins, 2011 – valid
  Hydraena truncata Rey, 1885 – valid
  Hydraena truncata falzonii Pretner, 1930 – valid
  Hydraena truncata truncata Rey, 1885 – valid
  Hydraena tsushimaensis Jäch and Díaz, 2012 – valid
  Hydraena tubuliphallis Jäch, 1982 – valid
  Hydraena tucumanica Perkins, 1980 – valid
  Hydraena tuolumne Perkins, 1980 – valid
  Hydraena turcica Janssens, 1965 – valid
  Hydraena turrialba Perkins, 1980 – valid
  Hydraena tyrrhena Binaghi, 1961 – valid
  Hydraena ulna Perkins, 2011 – valid
  Hydraena umbolenta Perkins, 2011 – valid
  Hydraena unca Valladares, 1989 – valid
  Hydraena undevigintioctogintasisyphos Jäch and Díaz, 2005 – valid
  Hydraena undulata Jäch and Díaz, 1998 – valid
  Hydraena uniforma Perkins, 2014 – valid
  Hydraena unita Perkins, 2011 – valid
  Hydraena uzbekistanica Jäch, 1994 – valid
  Hydraena vadosa Perkins, 2014 – valid
  Hydraena valentini Jäch and Díaz, 2012 – valid
  Hydraena valladaresi Lagar and Fresneda, 1990 – invalid
  Hydraena vandykei Orchymont, 1923 – valid
  Hydraena variopaca Perkins, 2011 – valid
  Hydraena vedrasi Orchymont, 1931 – valid
  Hydraena vela Perkins, 1980 – valid
  Hydraena velvetina Perkins, 2011 – valid
  Hydraena venezuela Perkins, 2011 – valid
  Hydraena verberans Jäch and Díaz, 2006 – valid
  Hydraena verstraeteni Ferro, 1984 – valid
  Hydraena victoriae Jäch and Díaz, 1999 – valid
  Hydraena vietnamensis (Janssens, 1972) – valid
  Hydraena virginalis Janssens, 1963 – valid
  Hydraena vodozi Sainte-Claire Deville, 1908 – valid
  Hydraena vulgaris Jäch and Díaz, 2000 – valid
  Hydraena waldheimi Jäch, 1987 – valid
  Hydraena wangi Jäch and Díaz, 1998 – valid
  Hydraena wangmiaoi Jäch and Díaz, 2005 – valid
  Hydraena watanabei Jäch and Satô, 1988 – valid
  Hydraena wattsi Perkins, 2007 – valid
  Hydraena weigeli Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena weiri Perkins, 2007 – valid
  Hydraena wencke Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena wewalkai Jäch, 1988 – valid
  Hydraena williamsensis Deane, 1931 – valid
  Hydraena wittmeri Satô, 1979 – valid
  Hydraena wolfi Skale and Jäch in Jäch and Skale, 2009 – valid
  Hydraena wrasei Jäch, 1992 – valid
  Hydraena xingu Perkins, 2011 – valid
  Hydraena yangae Jäch, Díaz and Skale, 2013 – valid
  Hydraena yonaguniensis Jäch and Díaz, 2003 – valid
  Hydraena yosemitensis Perkins, 1980 – valid
  Hydraena yoshitomii Jäch and Díaz, 1999 – valid
  Hydraena youngi Perkins, 1980 – valid
  Hydraena ypsilon Zwick, 1977 – valid
  Hydraena yunnanensis Pu, 1942 – valid
  Hydraena zapatina Perkins, 1980 – valid
  Hydraena zelandica Ordish, 1984 – valid
  Hydraena zetteli Freitag and Jäch, 2007 – valid
  Hydraena zezerensis Díaz Pazos and Bilton, 1995 – valid
  Hydraena zimbabwensis Perkins, 2014 – valid
  Hydraena zwicki Perkins, 2007 – valid
  Hydraenida Germain, 1901 – valid
  Hydraenida franzi Jäch, 1998 – valid
  Hydraenida guerreroi Ribera, 2000 – valid
  Hydraenida ocellata Germain, 1901 – valid
  Hydraenida robusta Perkins, 1980 – valid
  Hydraenida sanctijacobi Jäch, 1998 – valid
  Hydraenidae Mulsant, 1844 – valid – minute moss beetles
  Hydraenidini Perkins, 1980 – valid
  Hydraeninae Mulsant, 1844 – valid
  Hydraenini Mulsant, 1844 – valid
  Hydraethiops Günther, 1872 – valid
  Hydraethiops laevis Boulenger, 1904 – valid
  Hydraethiops melanogaster Günther, 1872 – valid – Blackbelly Snake
  Hydrallmania Hincks, 1868 – valid
  Hydrallmania distans Nutting, 1899 – valid
  Hydrallmania falcata (Linnaeus, 1758) – valid – sickle hydroid, sickle hydroid
  Hydrallmania franciscana (Trask, 1857) – valid
  Hydramara Knisch, 1925 – valid
  Hydramara argentina (Knisch, 1925) – valid
  Hydranassa Baird, 1858 – invalid
  Hydranassa tricolor (Statius Muller, 1776) – invalid
  Hydranassa tricolor ruficollis (Gosse, 1847) – invalid
  Hydrangeocola Brèthes, 1927 – valid
  Hydrangeocola atypica (Fischer, 1968) – valid
  Hydrangeocola bolsoni Papp, 1992 – valid
  Hydrangeocola chilana (Fischer, 1968) – valid
  Hydrangeocola coartata Papp, 1992 – valid
  Hydrangeocola espinosai Brèthes, 1927 – valid
  Hydrangeocola llaollin Martínez, 2018 – valid
  Hydrangeocola perardua Papp, 1992 – valid
  Hydrangeocola riogolgolensis (Fischer, 1968) – valid
  Hydrangeocola santiagana (Fischer, 1968) – valid
  Hydrangeocola topali Papp, 1992 – valid
  Hydrangeocola transversa Papp, 1992 – valid
  Hydrangeocola tubifrons (Fischer, 1968) – valid
  Hydrargira limi Kirtland, 1841 – invalid
  Hydrargyra atricauda DeKay, 1842 – invalid
  Hydrargyra fusca Thompson, 1842 – invalid
  Hydraspis Bell, 1828 – invalid
  Hydraspis australis Gray, 1841 – invalid
  Hydraspis bicolor Gray, 1873 – invalid
  Hydraspis bitentaculata Gray, 1831 – invalid
  Hydraspis boulengeri Bohls, 1895 – invalid
  Hydraspis constricta Gray, 1831 – invalid
  Hydraspis gordoni Gray, 1868 – invalid
  Hydraspis lutzi Ihering in Luederwaldt, 1926 – invalid
  Hydraspis maculata Gray, 1873 – invalid
  Hydrasterias Sladen, 1889 – valid
  Hydrasterias diomediae Ludwig, 1905 – invalid
  Hydrasterias improvisus (Ludwig, 1905) – valid
  Hydrasterias ophidion (Sladen, 1889) – valid
  Hydrasterias ophiodon A. M. Clark in Herring, 1974 – invalid
  Hydrasterias sacculata McKnight, 2006 – valid
  Hydrasterias sexradiata (Perrier in Milne-Edwards, 1882) – valid
  Hydrasterias tasmanica McKnight, 2006 – valid
  Hydrasterias verrilli Fisher, 1906 – invalid
  Microhydra Potts, 1885 – invalid
  Orstom hydratemei Raven & Churchill, 1994 – valid
  Otohydra Swedmark and Teissier, 1958 – valid
  Otohydra vagans Swedmark and Teissier, 1958 – valid
  Parephydra humilis Coquillett, 1902 – invalid
  Parhydraena Orchymont, 1937 – valid
  Parhydraena (Decarthrocerus) Orchymont, 1948 – invalid
  Parhydraena (Parhydraena) Orchymont, 1937 – valid
  Parhydraena ancylis Perkins, 2009 – valid
  Parhydraena asperita Perkins, 2009 – valid
  Parhydraena brahma Perkins, 2009 – valid
  Parhydraena brevipalpis (Régimbart, 1906) – valid
  Parhydraena brunovacca Perkins, 2009 – valid
  Parhydraena cooperi Orchymont, 1948 – invalid
  Parhydraena divisa Perkins, 2009 – valid
  Parhydraena faeni Bilton, 2014 – valid
  Parhydraena jeanneli (Orchymont, 1948) – invalid
  Parhydraena lancicula Perkins and Balfour-Browne, 1994 – valid
  Parhydraena maculicollis Perkins, 2009 – valid
  Parhydraena maureenae Perkins, 2009 – valid
  Parhydraena mpumalanga Perkins, 2009 – valid
  Parhydraena namaqua Perkins, 2009 – valid
  Parhydraena ora Perkins, 2009 – valid
  Parhydraena parva Perkins, 2009 – valid
  Parhydraena rugosa Orchymont, 1948 – valid
  Parhydraena sebastiani Perkins, 2009 – valid
  Parhydraena semicostata Perkins, 2009 – valid
  Parhydraena seriata Balfour-Browne, 1954 – valid
  Parhydraena similis Orchymont, 1948 – valid
  Parhydraena toro Perkins, 2009 – valid
  Parhydraenida Balfour-Browne, 1975 – valid
  Parhydraenida alida Balfour-Browne, 1975 – valid
  Parhydraenida bubrunipes Perkins, 1980 – valid
  Parhydraenida effeminata Balfour-Browne, 1975 – valid
  Parhydraenida hygropetrica Perkins, 1980 – valid
  Parhydraenida lambda Perkins, 1980 – valid
  Parhydraenida paralonga Perkins, 1980 – valid
  Parhydraenida pentatenkta Perkins, 1980 – valid
  Parhydraenida quadraticeps Balfour-Browne, 1975 – valid
  Parhydraenida reichardti Balfour-Browne, 1975 – valid
  Parhydraenini Perkins, 1997 – valid
  Parhydraenopsis Perkins, 2009 – valid
  Parhydraenopsis alta Perkins, 2009 – valid
  Parhydraenopsis cooperi (Orchymont, 1948) – valid
  Parhydraenopsis simiensis Perkins, 2009 – valid
  Pelagohydra Dendy, 1902 – valid
  Pelagohydra mirabilis Dendy, 1902 – valid
  Pogonephydra chalybea Hendel, 1917 – invalid
  Polyhydra Stechow, 1962 – valid
  Polyhydra calcarea (Carter, 1877) – valid
  Protohydra Greef, 1869 – valid
  Protohydra leuckarti Greeff, 1870 – valid
  Rapipontonia hydra Marin, 2009 – valid
  Rhynchohydracaridae – valid
  Rhynchohydracarus Lundblad, 1936 – valid
  Sagamihydra Hirohito, 1995 – valid
  Sagamihydra dyssymetra (Billard, 1929) – valid
  Sertularella hydrallmaniaeformis – valid
  Shepardhydras García, 2018 – valid
  Shepardhydras dytiscoide García, 2018 – valid
  Shepardhydras liliamarquezae Reyes, Briceño and García, 2023 – valid
  Shepardhydras zulia García, 2019 – valid
  Sigara hydratotrephes (Kirkaldy, 1908) – invalid
  Sphecodes hydrangeae Mitchell, 1956 – valid
  Stephanitis hydrangeae Drake and Maa, 1955 – valid
  Stephanohydra fusca Tschudi, 1837 – invalid
  Trichydra Wright, 1858 – valid
  Trichydra pudica Wright, 1858 – valid
 
 Kingdom Bacteria
  Vasilyevaea enhydra (Staley, 1968) Yee et al., 2010 – valid
 
 Kingdom Plantae
  Euphorbia melanohydrata Nel – accepted
  Euphorbia melanohydrata ssp. conica Swanepoel – accepted
  Euphorbia melanohydrata ssp. melanohydrata Nel – accepted
  Hydrangea L. – accepted – hydrangea
  Hydrangea arborescens L. – accepted – smooth hydrangea, wild hydrangea
  Hydrangea arborescens ssp. discolor (Ser. ex DC.) E.M. McClint. – not accepted
  Hydrangea arborescens ssp. radiata (Walter) E.M. McClint. – not accepted
  Hydrangea arborescens var. arborescens Linnaeus – not accepted
  Hydrangea arborescens var. deamii H. St. John – not accepted
  Hydrangea arborescens var. discolor Ser. – not accepted
  Hydrangea arborescens var. oblonga Torr. & A. Gray – not accepted
  Hydrangea arborescens var. sterilis Torr. & A. Gray – not accepted
  Hydrangea ashei Harb. – not accepted
  Hydrangea cinerea Small – accepted – ashy hydrangea
  Hydrangea macrophylla (Thunb.) Ser. – accepted – French hydrangea
  Hydrangea paniculata Siebold – accepted – panicled hydrangea
  Hydrangea quercifolia Bartram – accepted – oakleaf hydrangea
  Hydrangea radiata Walter – accepted – silverleaf hydrangea
  Hydrangeaceae – accepted – hydrangeas
  Hydrangeales – not accepted
  Hydranthelium rotundifolium (Michx.) Pennell – not accepted
  Hydrastidaceae – not accepted
  Hydrastidales – not accepted
  Hydrastis L. – accepted
  Hydrastis canadensis L. – accepted – goldenseal
  Riccardia hydra Hürl. – accepted
  Schizophragma hydrandeoides Siebold & Zucc. – not accepted
  Schizophragma hydrangeoides Siebold & Zucc. – accepted – climbing hydrangea vine
 
 Kingdom Protozoa
  Hydramoeba Reynolds and Looper, 1928 – valid
  Hydramoeba hydroxena – valid
   

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