Hydraena zijn een geslacht  van kevers uit de familie van de waterkruipers (Hydraenidae). Ruim 900 soorten zijn bij het geslacht ingedeeld.

Taxonomie 
O.a. de volgende soorten zijn bij het geslacht ingedeeld:
 Hydraena abbasigili Jäch, 1988
 Hydraena abdita Orchymont, 1948
 Hydraena abyssinica Régimbart, 1905
 Hydraena accurata Orchymont, 1948
 Hydraena achaica Jäch, 1995
 Hydraena acumena Perkins, 2011
 Hydraena adelbertensis Perkins, 2011
 Hydraena adrastea Orchymont, 1948
 Hydraena aethaliensis Breit, 1917
 Hydraena affirmata Perkins, 2007
 Hydraena affusa Orchymont, 1936
 Hydraena africana Kuwert, 1888
 Hydraena akameku Perkins, 2011
 Hydraena akbesiana Audisio, De Biase & Jäch, 1993
 Hydraena albai Sáinz-Cantero, 1993
 Hydraena alberti Balfour-Browne, 1950
 Hydraena alcantarana Ienistea, 1985
 Hydraena algerina Kaddouri, 1992
 Hydraena alia Orchymont, 1934
 Hydraena aliciae Jäch and Díaz, 2005
 Hydraena allomorpha Lagar & Fresneda, 1990
 Hydraena alluaudi Régimbart, 1906
 Hydraena alpicola Pretner, 1931
 Hydraena altamirensis Díaz Pazos & Garrido Gonzalez, 1993
 Hydraena altapapua Perkins, 2011
 Hydraena alternata Perkins, 1980
 Hydraena alterra Perkins, 1980
 Hydraena alticola Skale and Jäch, 2008
 Hydraena altiphila Perkins, 2011
 Hydraena amazonica Perkins, 2011
 Hydraena ambiflagellata Zwick, 1977
 Hydraena ambigua Ganglbauer 1901
 Hydraena ambiosina Perkins, 2007
 Hydraena ambra Perkins, 2011
 Hydraena ambripes Perkins, 2011
 Hydraena ambroides Perkins, 2011
 Hydraena americana Jäch, 1993
 Hydraena amidensis Jäch, 1988
 Hydraena ampla Perkins, 2011
 Hydraena anaphora Perkins, 1980
 Hydraena anatolica Janssens, 1963
 Hydraena anatolica Janssens, 1963
 Hydraena ancylis Perkins, 1980
 Hydraena ancyrae Jäch, 1992
 Hydraena andalusa Lagar & Fresneda, 1990
 Hydraena andreinii Orchymont, 1934
 Hydraena angulicollis Notman, 1921
 Hydraena angulosa Mulsant, 1844
 Hydraena angustata Sturm, 1836
 Hydraena anisonycha Perkins, 1980
 Hydraena antaria Perkins, 2007
 Hydraena antiatlantica Jäch, Aguilera, and Hernando, 1998
 Hydraena antiochena Jäch, 1988
 Hydraena apertista Perkins, 2011
 Hydraena apexa Perkins, 2011
 Hydraena appalachicola Perkins, 1980
 Hydraena appetita Perkins, 2007
 Hydraena aquila Perkins, 2011
 Hydraena arabica Balfour-Browne, 1951
 Hydraena arachthi Ferro & Jäch, 2000
 Hydraena arcta Perkins, 2007
 Hydraena arenicola Perkins, 1980
 Hydraena argutipes Perkins, 1980
 Hydraena ariana Janssens, 1962
 Hydraena arizonica Perkins, 1980
 Hydraena armata Reitter, 1880
 Hydraena armeniaca Janssens, 1968
 Hydraena armipalpis Jäch and Díaz, 2000
 Hydraena armipes Rey, 1886
 Hydraena aroensis (Ferro, 1991) stat. nov. 
 Hydraena arunensis Skale and Jäch in Jäch and Skale, 2009
 Hydraena ascensa Perkins, 2007
 Hydraena assimilis Rey 1885
 Hydraena athertonica Perkins, 2007
 Hydraena atrata Desbrochers des Loges, 1891
 Hydraena atroscintilla Perkins, 2011
 Hydraena attaleiae Ferro, 1984
 Hydraena audisioi Jäch, 1992
 Hydraena aulaarta Perkins, 2011
 Hydraena aurita Jäch, 1988
 Hydraena australica Zwick, 1977
 Hydraena australula Perkins, 2007
 Hydraena austrobesa Perkins, 2011
 Hydraena avuncula Jäch, 1988
 Hydraena bacchusi Perkins, 2011
 Hydraena bactriana Janssens, 1962
 Hydraena balearica Orchymont, 1930
 Hydraena balfourbrownei Bameul, 1986
 Hydraena balkei Perkins, 2011
 Hydraena balli Orchymont, 1940
 Hydraena barbipes Zwick, 1977
 Hydraena barricula Perkins, 1980
 Hydraena barrosi Orchymont, 1934
 Hydraena bedeli Barthélemy, 1992
 Hydraena belgica d’Orchymont, 1930
 Hydraena beniensis Perkins, 2011
 Hydraena benjaminus Jäch and Díaz, 2006
 Hydraena bensae Ganglbauer, 1901
 Hydraena bergeri (Janssens, 1972)
 Hydraena berthelemyana Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006
 Hydraena berytus Jäch, 1986
 Hydraena beyarslani Jäch, 1988
 Hydraena bicarinova Perkins, 2011
 Hydraena bicolorata Jäch, 1997
 Hydraena bicuspidata Ganglbauer 1901
 Hydraena bicuspidata Ganglbauer, 1901
 Hydraena bidefensa Perkins, 2007
 Hydraena bifunda Perkins, 2011
 Hydraena bihamata Champion, 1920
 Hydraena biimpressa Perkins, 2007
 Hydraena billi Zwick, 1977
 Hydraena bilobata Jäch and Díaz, 1998
 Hydraena bimagua Jäch, 1986
 Hydraena birendra Skale and Jäch in Jäch and Skale, 2009
 Hydraena bispinosa Pu, 1951
 Hydraena bisulcata Rey, 1884
 Hydraena bitruncata d’Orchymont, 1934
 Hydraena bituberculata Perkins, 1980
 Hydraena biundulata Perkins, 2011
 Hydraena blackburni Zaitzev, 1908
 Hydraena bodemeyeri Jäch and Díaz, 2001
 Hydraena boetcheri Orchymont, 1932
 Hydraena bolivari Orchymont, 1936
 Hydraena boliviana Perkins, 2011
 Hydraena bononiensis Binaghi, 1960
 Hydraena bononiensis Chiesa, 1959
 Hydraena borbonica Fairmaire, 1898
 Hydraena bosnica Apfelbeck, 1909
 Hydraena brachymera Orchymont, 1936
 Hydraena bractea Perkins, 1980
 Hydraena bractoides Perkins, 1980
 Hydraena brahmin Perkins, 2011
 Hydraena breedlovei Perkins, 1980
 Hydraena brevis Sharp 1882
 Hydraena britteni Joy, 1907
 Hydraena brittoni Zwick, 1977
 Hydraena bromleyae Jäch, 1986
 Hydraena browni Perkins, 1980
 Hydraena bubulla Perkins, 2011
 Hydraena bulgarica Breit, 1916
 Hydraena buloba Perkins, 2011
 Hydraena buquintana Perkins, 2011
 Hydraena buscintilla Perkins, 2011
 Hydraena busuanga Freitag and Jäch, 2007
 Hydraena calcarifera Janssens, 1959
 Hydraena californica Perkins, 1980
 Hydraena campbelli Perkins, 1980
 Hydraena canakcioglui Janssens 1965
 Hydraena canticacollis Perkins, 1980
 Hydraena capacis Perkins, 2007
 Hydraena capetribensis Perkins, 2007
 Hydraena cappadocica Jäch, 1988
 Hydraena capta Orchymont, 1936
 Hydraena carbonaria Kiesenwetter, 1849
 Hydraena carica Jäch, 1988
 Hydraena carinocisiva Perkins, 2011
 Hydraena carinulata Rey, 1886
 Hydraena carmellita Perkins, 2011
 Hydraena carniolica Pretner, 1970
 Hydraena castanea Deane, 1937
 Hydraena castanescens Freitag and Jäch, 2007
 Hydraena cata d’Orchymont, 1936
 Hydraena cata Orchymont, 1943
 Hydraena catalonica Fresneda, Aguilera & Hernando, 1994
 Hydraena catherinae Bameul and Jäch, 2001
 Hydraena caucasica Kuwert, 1888
 Hydraena cavifrons Perkins, 2011
 Hydraena cephalleniaca Jäch, 1985
 Hydraena cervisophila Jäch, 1992
 Hydraena challeti Perkins, 2011
 Hydraena cheesmanae Perkins, 2011
 Hydraena chenae Pu 1951
 Hydraena chersonesica Jäch, Díaz and Przewozny, 2007
 Hydraena cherylbarrae Perkins, 2011
 Hydraena chiapa Perkins, 1980
 Hydraena chiesai Janssens 1965
 Hydraena chifengi Jäch and Díaz, 1999
 Hydraena chobauti Guillebeau 1896
 Hydraena christinae Audisio, De Biase & Jäch, 1996
 Hydraena christoferi Jäch and Díaz, 2005
 Hydraena ciliciensis Jäch, 1988
 Hydraena circulata Perkins, 1980
 Hydraena cirrata Champion, 1920
 Hydraena clarinis Perkins, 2011
 Hydraena claudia Freitag and Jäch, 2007
 Hydraena clavigera Zwick, 1977
 Hydraena clemens Jäch and Díaz, 2006
 Hydraena clinodorsa Perkins, 2011
 Hydraena clystera Perkins, 2011
 Hydraena cochabamba Perkins, 2011
 Hydraena colchica Janssens, 1963
 Hydraena colombiana Perkins, 1980
 Hydraena colorata Perkins, 2011
 Hydraena colymba Perkins, 1980
 Hydraena compressipilis Jäch and Díaz, 1998
 Hydraena concepcionica Perkins, 2011
 Hydraena concinna Orchymont, 1932
 Hydraena confluenta Perkins, 2011
 Hydraena confusa Pu, 1951
 Hydraena connexa Orchymont, 1932
 Hydraena converga Perkins, 2007
 Hydraena coomani Orchymont, 1932
 Hydraena cooperi Balfour-Browne, 1954
 Hydraena copulata Perkins, 2011
 Hydraena cordata Schaufuss, 1883
 Hydraena cordiformis Jäch and Díaz, 2000
 Hydraena cordispina Perkins, 2011
 Hydraena corinna Orchymont, 1936
 Hydraena cornelli Jäch and Díaz, 1998
 Hydraena corrugis Orchymont, 1934
 Hydraena coryleti Jäch, 1992
 Hydraena costiniceps Perkins, 1980
 Hydraena crepidoptera Jäch, 1992
 Hydraena cristatigena Jäch and Díaz, 2000
 Hydraena croatica Kuwert, 1888
 Hydraena cryptostoma Jäch, 1992
 Hydraena crystallina Perkins, 1980
 Hydraena cubista Perkins, 2007
 Hydraena cultrata Perkins, 2007
 Hydraena cunicula Perkins, 2011
 Hydraena cunninghamensis Perkins, 2007
 Hydraena curta Kiesenwetter, 1849
 Hydraena curtipalpis Jäch and Díaz, 1998
 Hydraena curvosa Perkins, 2011
 Hydraena cuspidicollis Perkins, 1980
 Hydraena cyclops Jäch and Díaz, 2000
 Hydraena cygnus Zwick, 1977
 Hydraena czernohorskyi J. Müller, 1911
 Hydraena d-concava Perkins, 2011
 Hydraena dalmatina Ganglbauer, 1901
 Hydraena damascena Pic, 1910
 Hydraena dariensis Perkins, 2011
 Hydraena darwini Perkins, 2007
 Hydraena d-destina Perkins, 1980
 Hydraena debeckeri (Janssens, 1972)
 Hydraena decepta Perkins, 2011
 Hydraena decipiens Zwick, 1977
 Hydraena decolor Sainte-Claire Deville, 1903
 Hydraena decui Spangler, 1980
 Hydraena delia Balfour-Browne, 1978
 Hydraena deliquesca Perkins, 2007
 Hydraena delvasi Delgado and Collantes, 1996
 Hydraena densa Fauvel, 1883
 Hydraena dentipalpis Reitter, 1888
 Hydraena dentipes Germar, 1824
 Hydraena dentipes Germar, 1842
 Hydraena devillei Ganglbauer, 1901
 Hydraena devincta d’Orchymont, 1940
 Hydraena diadema Perkins, 2011
 Hydraena diazi Trizzino, Jäch & Ribera, 2011
 Hydraena diffusa Perkins, 2011
 Hydraena dilutipes Fairmaire, 1898
 Hydraena dimorpha Orchymont, 1922
 Hydraena dinosaurophila Jäch, 1994
 Hydraena discicollis Fairmaire, 1898
 Hydraena discreta Ganglbauer, 1904
 Hydraena disparamera Perkins, 2007
 Hydraena dochula Skale and Jäch in Jäch and Skale, 2009
 Hydraena dolichogaster Janssens, 1965
 Hydraena dorrigoensis Perkins, 2007
 Hydraena draconisaurati Jäch and Díaz, 2005
 Hydraena dudgeoni Perkins, 2011
 Hydraena duohamata Perkins, 2011
 Hydraena ebriimadli Jäch, 1988
 Hydraena ecuadormica Perkins, 2011
 Hydraena egoni Jäch, 1986
 Hydraena eichleri Orchymont 1937
 Hydraena einsteini Perkins, 2011
 Hydraena elisabethae Jäch, 1992
 Hydraena eliya Jäch, 1982
 Hydraena emarginata Rey, 1885
 Hydraena emineae Jäch and Kasapoglu, 2006
 Hydraena epeirosi Ferro, 1985
 Hydraena errina Orchymont, 1948
 Hydraena erythraea Régimbart, 1905
 Hydraena eryx Orchymont, 1948
 Hydraena essentia Perkins, 2011
 Hydraena eucnemis Janssens, 1970
 Hydraena evanescens Rey, 1884
 Hydraena evansi Balfour-Browne, 1945
 Hydraena exarata Kiesenwetter, 1866
 Hydraena exasperata d’Orchymont, 1935
 Hydraena excisa Kiesenwetter, 1849
 Hydraena exhalista Perkins, 2011
 Hydraena exilipes Perkins, 1980
 Hydraena expedita Skale and Jäch in Jäch and Skale, 2009
 Hydraena explanata Pic 1905
 Hydraena extorris Zwick, 1977
 Hydraena falcata Jäch, 1992
 Hydraena fasciata Perkins, 2011
 Hydraena fascinata <Perkins, 2011
 Hydraena fasciola Perkins, 2011
 Hydraena fasciolata Perkins, 2011
 Hydraena fasciopaca Perkins, 2011
 Hydraena fenestella Perkins, 2011
 Hydraena ferethula Perkins, 2007
 Hydraena feuerborni Orchymont, 1932
 Hydraena fijiensis Balfour-Browne, 1945
 Hydraena filum Sahlberg, 1908
 Hydraena finita Orchymont, 1943
 Hydraena finki Skale and Jäch in Jäch and Skale, 2009
 Hydraena finniganensis Perkins, 2007
 Hydraena fiorii Porta, 1899
 Hydraena fischeri Schönmann, 1991
 Hydraena flagella Perkins, 2011
 Hydraena fluvicola (Perkins, 1980)
 Hydraena foliobba Perkins, 2011
 Hydraena fontana Orchymont, 1932
 Hydraena fontiscarsavii (Jäch, 1988)
 Hydraena formosopala Perkins, 2011
 Hydraena formula Orchymont, 1932
 Hydraena forticollis Perkins, 2007
 Hydraena fosterorum Trizzino, Jäch & Ribera, 2011
 Hydraena freitagi Skale and Jäch in Jäch and Skale, 2009
 Hydraena frenzeli Skale and Jäch, 2008
 Hydraena fritzi Jäch, 1992
 Hydraena frondsicola (Perkins, 1980)
 Hydraena funda Perkins, 2011
 Hydraena fundacta Perkins, 2011
 Hydraena fundaequalis Perkins, 2007
 Hydraena fundapta Perkins, 2011
 Hydraena fundarca Perkins, 2011
 Hydraena fundata Perkins, 2007
 Hydraena fundextra Perkins, 2011
 Hydraena furthi Jäch, 1982
 Hydraena gaditana Lagar & Fresneda, 1990
 Hydraena galatica Janssens, 1970
 Hydraena galea Perkins, 2011
 Hydraena gattolliati 
 Hydraena gavarrensis Jäch, Díaz and Martinoy, 2005
 Hydraena geminya Perkins, 1980
 Hydraena georgiadesi Orchymont, 1931
 Hydraena geraldneuhauseri Jäch and Díaz, 2006
 Hydraena germaini Orchymont, 1923
 Hydraena glassmani Jäch, 1986
 Hydraena gnatella Orchymont, 1945
 Hydraena gnatelloides Orchymont, 1945
 Hydraena gracilidelphis Trizzino, Valladares, Garrido & Audisio, 2012
 Hydraena gracilis Germar, 1824
 Hydraena graciloides (Jäch, 1988)
 Hydraena grandis Reitter, 1885
 Hydraena graphica Orchymont, 1931
 Hydraena grata Orchymont, 1944
 Hydraena gregalis Orchymont, 1944
 Hydraena gressa Orchymont, 1944
 Hydraena griphus Orchymont, 1944
 Hydraena grouvellei Orchymont, 1923
 Hydraena grueberi Skale and Jäch in Jäch and Skale, 2009
 Hydraena guadelupensis Orchymont, 1923
 Hydraena guangxiensis Jäch and Díaz, 2005
 Hydraena guatemala Perkins, 1980
 Hydraena guentheri Jäch, 1992
 Hydraena guilin Jäch and Díaz, 2005
 Hydraena gynaephila Jäch, 1997
 Hydraena hainzi Jäch, 1988
 Hydraena haitensis Perkins, 1980
 Hydraena hamifera Zwick, 1977
 Hydraena hansreuteri Jäch and Díaz, 2005
 Hydraena helena Orchymont, 1929
 Hydraena hernandoi Fresneda & Lagar, 1990
 Hydraena herzogestella Perkins, 2011
 Hydraena heterogyna Bedel 
 Hydraena hiekei Jäch, 1992
 Hydraena hillaryi Skale and Jäch in Jäch and Skale, 2009
 Hydraena hintoni Perkins, 2011
 Hydraena hispanica Ganglbauer, 1901
 Hydraena holdhausi Pretner, 1929
 Hydraena hornabrooki Perkins, 2011
 Hydraena hortensis Jäch & Díaz, 2000
 Hydraena hosiwergi Freitag and Jäch, 2007
 Hydraena hosseinieorum Bilton & Jäch, 1998
 Hydraena huangshanensis Jäch and Díaz, 2005
 Hydraena huitongensis Jäch and Díaz, 2005
 Hydraena hunanensis Pu, 1951
 Hydraena hungarica Rey, 1884
 Hydraena huonica Perkins, 2011
 Hydraena hyalina Perkins, 1980
 Hydraena hynesi Zwick, 1977
 Hydraena hypipamee Perkins, 2007
 Hydraena ibalimi Perkins, 2011
 Hydraena iberica d’Orchymont, 1936
 Hydraena idema Perkins, 2011
 Hydraena iheya Jäch and Díaz, 1999
 Hydraena ilamensis Skale and Jäch in Jäch and Skale, 2009
 Hydraena ilica Jäch, 1994
 Hydraena imbria Jäch & Díaz, 2001
 Hydraena impala Perkins, 2011
 Hydraena imperatrix Kniz, 1919
 Hydraena impercepta Zwick, 1977
 Hydraena impressicollis Fairmaire, 1898
 Hydraena inancala Perkins, 2007
 Hydraena inapicipalpis Pic, 1918
 Hydraena incisiva Perkins, 2011
 Hydraena incista Perkins, 2011
 Hydraena incurva Orchymont, 1932
 Hydraena indiana Jäch, 1994
 Hydraena indica Orchymont, 1920
 Hydraena infoveola Perkins, 2011
 Hydraena ingens (Perkins, 1980)
 Hydraena inhalista Perkins, 2011
 Hydraena innuda Perkins, 2007
 Hydraena inopinata Jäch and Díaz, 1998
 Hydraena inplacopaca Perkins, 2011
 Hydraena insandalia Perkins, 2011
 Hydraena insita Orchymont, 1932
 Hydraena insolita Orchymont, 1932
 Hydraena insularis Orchymont, 1945
 Hydraena integra Pretner, 1931
 Hydraena intensa Perkins, 2011
 Hydraena intermedia Rosenhauer, 1847
 Hydraena intraangulata Perkins, 2007
 Hydraena inusta Orchymont, 1932
 Hydraena invicta Perkins, 2007
 Hydraena iriomotensis Jäch and Díaz, 1999
 Hydraena isabelae Castro & Herrera, 2001
 Hydraena isolinae Jäch and Díaz, 1998
 Hydraena ispirensis Kasapoglu, Jäch and Skale, 2010
 Hydraena iterata Orchymont, 1948
 Hydraena jacobsoni Orchymont, 1932
 Hydraena jaechiana (Audisio & De Biase, 1990) 
 Hydraena jaegeri Skale and Jäch in Jäch and Skale, 2009
 Hydraena jailensis Breit, 1917
 Hydraena janczyki Jäch, 1992
 Hydraena janeceki Jäch, 1987
 Hydraena janssensi Nilsson, 2001
 Hydraena jengi Jäch and Díaz, 1998
 Hydraena jilanzhui Jäch and Díaz, 2005
 Hydraena jivaro Perkins, 1980
 Hydraena johncoltranei Perkins, 2011
 Hydraena jubilata Perkins, 2011
 Hydraena kakadu Perkins, 2007
 Hydraena karinkukolae Jäch, 1989
 Hydraena karmai Skale and Jäch in Jäch and Skale, 2009
 Hydraena kasyi Jäch, 1992
 Hydraena kaufmanni Ganglbauer 1901
 Hydraena kellymilleri Perkins, 2011
 Hydraena khnzoriani Janssens, 1968
 Hydraena kilimandjarensis Régimbart, 1906
 Hydraena knischi Orchymont, 1928
 Hydraena kocheri Berthélemy, 1992
 Hydraena kodadai Freitag and Jäch, 2007
 Hydraena koje Perkins, 2011
 Hydraena koma Perkins, 2011
 Hydraena krasnodarensis Jäch & Díaz, 2006
 Hydraena kroumiriana Kaddouri, 1992
 Hydraena kucinici 
 Hydraena kuehnelti Jäch, 1989
 Hydraena kurdistanica Jäch, 1988
 Hydraena kwangsiensis Pu, 1951
 Hydraena labropaca Perkins, 2011
 Hydraena lapidicola Kiesenwetter, 1849
 Hydraena lapissectilis Jäch, 1992
 Hydraena larissae Jäch & Díaz, 2000
 Hydraena larsoni Perkins, 2007
 Hydraena lassulipes Perkins, 2011
 Hydraena latebricola Jäch, 1986
 Hydraena latisoror Perkins, 2007
 Hydraena lazica Janssens, 1963
 Hydraena leechi Perkins, 1980
 Hydraena leei Jäch and Díaz, 1998
 Hydraena legorskyi 
 Hydraena lehmanni Jäch and Díaz, 2005
 Hydraena leonhardi Breit, 1916
 Hydraena leprieuri Sainte-Claire Deville, 1905
 Hydraena levantina Sahlberg, 1908
 Hydraena ligulipes Jäch, 1988
 Hydraena lilianae Perkins, 2011
 Hydraena limbobesa Perkins, 2011
 Hydraena limpidicollis Perkins, 1980
 Hydraena liriope Orchymont, 1943
 Hydraena longicollis Sharp 1882
 Hydraena loripes Perkins, 2011
 Hydraena lucasi Lagar, 1984
 Hydraena lucernae Zwick, 1977
 Hydraena ludovicae Orchymont, 1931
 Hydraena luminicollis Perkins, 2007
 Hydraena luridipennis MacLeay, 1873
 Hydraena lusitana Berthélemy, 1977
 Hydraena lycia Jäch, 1988
 Hydraena macedonica Orchymont, 1931
 Hydraena maculicollis Champion, 1920
 Hydraena maculopala Perkins, 2011
 Hydraena madronensis Castro, Garcia & Ferreras, 2000
 Hydraena magna Pu, 1951
 Hydraena magnessa Jäch, 1997
 Hydraena magnetica Zwick, 1977
 Hydraena mahensis Scott, 1913
 Hydraena malickyi Jäch, 1989
 Hydraena malkini Perkins, 1980
 Hydraena manabica Perkins, 2011
 Hydraena manaslu Skale and Jäch in Jäch and Skale, 2009
 Hydraena manfredjaechi Delgado & Soler, 1991
 Hydraena manguao Freitag and Jäch, 2007
 Hydraena manulea Perkins, 2011
 Hydraena manuloides Perkins, 2011
 Hydraena marawaka Perkins, 2011
 Hydraena marcosae Aguilera, Hernando & Ribera, 1997
 Hydraena marginicollis Kiesenwetter, 1849
 Hydraena mariannae Jäch, 1992
 Hydraena marinae Castro, 2003
 Hydraena martensi Skale and Jäch in Jäch and Skale, 2009
 Hydraena martinschoepfi Jäch and Díaz, 2005
 Hydraena masatakai Jäch and Díaz, 2003
 Hydraena maureenae Perkins, 1980
 Hydraena mauriciogarciai Perkins, 2011
 Hydraena mazamitla Perkins, 1980
 Hydraena mecai Millán & Aguilera, 2000
 Hydraena melas Dalla Torre 1877
 Hydraena mercuriala Perkins, 2011
 Hydraena meschniggi Pretner, 1929
 Hydraena metzeni Perkins, 2007
 Hydraena mexicana Perkins, 1980
 Hydraena mianminica Perkins, 2011
 Hydraena mignymixys Perkins, 1980
 Hydraena millerorum Perkins, 2007
 Hydraena miniretia Perkins, 2007
 Hydraena mintrita Perkins, 2011
 Hydraena mitchellensis Perkins, 2007
 Hydraena miyatakei Satô, 1959
 Hydraena modili Jäch, 1988
 Hydraena monikae Jäch and Díaz, 2000
 Hydraena monscassius Jäch, 1988
 Hydraena monstruosipes Ferro, 1986
 Hydraena monteithi Perkins, 2007
 Hydraena morio Kiesenwetter, 1849
 Hydraena mouzaiensis Sainte-Claire Deville, 1909
 Hydraena muelleri Pretner, 1931
 Hydraena muezziginea Jäch, 1988
 Hydraena multiloba Perkins, 2011
 Hydraena multispina Perkins, 2011
 Hydraena mylasae Jäch, 1992
 Hydraena nanocolorata Perkins, 2011
 Hydraena nanopala Perkins, 2011
 Hydraena nanoscintilla Perkins, 2011
 Hydraena neblina Perkins, 2011
 Hydraena nelsonmandelai Makhan, 2008
 Hydraena nevermanni Perkins, 1980
 Hydraena newtoni Perkins, 1980
 Hydraena nielshaggei Freitag and Jäch, 2007
 Hydraena nigra Hatch 1965
 Hydraena nigrita Germar, 1824
 Hydraena nike Jäch, 1995
 Hydraena nilguenae (Jäch, 1988)
 Hydraena nitidimenta Perkins, 2011
 Hydraena nivalis Jäch, 1992
 Hydraena notsui Sato, 1978
 Hydraena novacula Perkins, 2011
 Hydraena numidica Sainte-Claire Deville, 1905
 Hydraena nuratauensis Jäch, 1994
 Hydraena oaxaca Perkins, 1980
 Hydraena oblio Perkins, 1980
 Hydraena occidentalis Perkins, 1980
 Hydraena occitana (Audisio & De Biase, 1995)
 Hydraena okapa Perkins, 2011
 Hydraena okinawensis Jäch and Díaz, 1999
 Hydraena olidipastoris Jäch, 1988
 Hydraena ollopa Perkins, 2011
 Hydraena orchis Jäch and Díaz, 1998
 Hydraena orcula Perkins, 1980
 Hydraena ordishi Delgado and Palma, 1997
 Hydraena orientalis Breit, 1916
 Hydraena ortali Jäch, 1986
 Hydraena orthosia Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006
 Hydraena otiarca Perkins, 2011
 Hydraena ovata Janssens, 1961
 Hydraena owenobesa Perkins, 2011
 Hydraena oxiana Janssens, 1974
 Hydraena ozarkensis Perkins, 1980
 Hydraena pachyptera Apfelbeck, 1909
 Hydraena pacifica Perkins, 1980
 Hydraena pacificica Perkins, 2011
 Hydraena paeminosa Perkins, 1980
 Hydraena pagaluensis Hernando and Ribera, 2001
 Hydraena paganettii Ganglbauer, 1901
 Hydraena pakistanica Jäch, 1992
 Hydraena pala Perkins, 2011
 Hydraena palamita Perkins, 2011
 Hydraena palawanensis Freitag and Jäch, 2007
 Hydraena pallidula Sainte-Claire Deville, 1909
 Hydraena palustris Erichson, 1837
 Hydraena pamirica Jäch, 1992
 Hydraena pamphylia Jäch and Díaz, 2001
 Hydraena pangaei Jäch, 1992
 Hydraena pantanalensis Perkins, 2011
 Hydraena paraguayensis Janssens 1972
 Hydraena parciplumea Perkins, 2007
 Hydraena particeps Perkins, 1980
 Hydraena parva Zwick, 1977
 Hydraena parysatis Janssens, 1981
 Hydraena paucistriata Jäch and Díaz, 2000
 Hydraena pavicula Perkins, 1980
 Hydraena paxillipes Perkins, 2011
 Hydraena peckorum Perkins, 2011
 Hydraena pectenata Perkins, 2011
 Hydraena pedroaguilerai Perkins, 2011
 Hydraena pegopyga Perkins, 2011
 Hydraena pelops Jäch, 1995
 Hydraena pensylvanica Kiesenwetter 1849
 Hydraena penultimata Perkins, 2011
 Hydraena perkinsi Spangler, 1980
 Hydraena perlonga Balfour-Browne, 1950
 Hydraena perpunctata Perkins, 2011
 Hydraena persica Janssens, 1981
 Hydraena pertransversa Perkins, 2011
 Hydraena peru Perkins, 1980
 Hydraena petila Perkins, 1980
 Hydraena phainops Perkins, 2011
 Hydraena phallerata Orchymont 1944
 Hydraena phallica d’Orchymont, 1930
 Hydraena phassilyi Orchymont, 1931
 Hydraena philippi Jäch and Díaz, 2005
 Hydraena philyra Orchymont, 1944
 Hydraena phoenicia Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006
 Hydraena photogenica Perkins, 2011
 Hydraena pici Sainte-Claire Deville, 1905
 Hydraena picula Perkins, 2011
 Hydraena pilipes Zwick, 1977
 Hydraena pilulambra Perkins, 2011
 Hydraena pindica Janssens, 1965
 Hydraena planata Kiesenwetter, 1849
 Hydraena planata Kiesenwetter, 1849
 Hydraena plastica d’Orchymont, 1943
 Hydraena platycnemis Jäch, 1988
 Hydraena platynaspis Jäch, 1988
 Hydraena platysoma Janssens, 1968
 Hydraena plaumanni Orchymont, 1937
 Hydraena plumipes Rey 1886
 Hydraena pluralticola Perkins, 2011
 Hydraena plurifurcata Jäch and Díaz, 1998
 Hydraena polita Kiesenwetter, 1849
 Hydraena pontequula Perkins, 1980
 Hydraena pontica Janssens, 1963
 Hydraena porchi Perkins, 2007
 Hydraena porcula Jäch and Díaz, 1998
 Hydraena praetermissa Jäch, 1987
 Hydraena premordica Perkins, 1980
 Hydraena pretneri Chiesa, 1927
 Hydraena prieto Perkins, 1980
 Hydraena princeps Fauvel, 1903
 Hydraena processa Perkins, 2011
 Hydraena producta Mulsant & Rey, 1852
 Hydraena prokini Jäch & Díaz, 2006
 Hydraena propria Perkins, 2011
 Hydraena prusensis Jäch, 1992
 Hydraena pseudocirrata Skale and Jäch in Jäch and Skale, 2009
 Hydraena pseudopalawanensis Freitag and Jäch, 2007
 Hydraena pseudoriparia Orchymont, 1945
 Hydraena puetzi Jäch, 1994
 Hydraena pugillista Perkins, 2007
 Hydraena pulchella Germar, 1824
 Hydraena pulsatrix Perkins, 1980
 Hydraena punctata LeConte, 1855
 Hydraena puncticollis Sharp 1882
 Hydraena punctilata Perkins, 2011
 Hydraena putearius Jäch and Díaz, 2000
 Hydraena pygmaea Waterhouse, 1833
 Hydraena quadrata (Janssens, 1980)
 Hydraena quadricollis Wollaston 1864
 Hydraena quadricurvipes Perkins, 1980
 Hydraena quadriplumipes Perkins, 2011
 Hydraena quechua Perkins, 1980
 Hydraena queenslandica Perkins, 2007
 Hydraena quetiae Castro, 2000
 Hydraena quilisi Lagar, Fresneda and Fernando, 1987
 Hydraena quintana Perkins, 2011
 Hydraena ramuensis Perkins, 2011
 Hydraena ramuquintana Perkins, 2011
 Hydraena receptiva Perkins, 2011
 Hydraena regimbarti Zaitzev, 1908
 Hydraena remulipes Perkins, 2011
 Hydraena reticulata Zwick, 1977
 Hydraena reticulobesa Perkins, 2011
 Hydraena reticuloides Perkins, 2007
 Hydraena reticulositis Perkins, 2007
 Hydraena revelovela Perkins, 2007
 Hydraena reverberata Perkins, 2011
 Hydraena reyi Kuwert, 1888
 Hydraena rhinoceros (Janssens, 1972)
 Hydraena rhodia Jäch, 1985
 Hydraena riberai Jäch, Aguilera, and Hernando, 1998
 Hydraena richardimbi Jäch, 1992
 Hydraena rigua Orchymont, 1931
 Hydraena ripaeaureae (Janssens, 1972)
 Hydraena riparia Kugelann, 1794
 Hydraena rivularis Guillebeau, 1896
 Hydraena robusta Zwick, 1977
 Hydraena rosannae Audisio, Trizzino and De Biase in Audio, Trizzino, De Biase, Mancini and Antonini, 2009
 Hydraena rudallensis Blackburn, 1896
 Hydraena rufipennis Boscá Berga, 1932
 Hydraena rufipes Curtis, 1830
 Hydraena rugosa Mulsant, 1844
 Hydraena ruinosa Zwick, 1977
 Hydraena rukiyeae Kasapoglu, Jäch and Skale, 2010
 Hydraena sabella Perkins, 1980
 Hydraena saga d’Orchymont, 1930
 Hydraena sagatai Perkins, 2011
 Hydraena sahlbergi Orchymont, 1923
 Hydraena saluta Perkins, 2011
 Hydraena samia Jäch, 1986
 Hydraena samnitica Fiori, 1904
 Hydraena samnitica Knisch, 1924
 Hydraena sanfilippoi (Audisio & De Biase, 1995) 
 Hydraena sappho Janssens, 1965
 Hydraena sardoa Binaghi, 1961
 Hydraena satoi Jäch and Díaz, 1999
 Hydraena sautakei Jäch and Díaz, 1999
 Hydraena sauteri Orchymont, 1913
 Hydraena scabra Orchymont, 1925
 Hydraena scabrosa Orchymont, 1931
 Hydraena schawalleri Skale and Jäch in Jäch and Skale, 2009
 Hydraena schilfii Jäch, 1988
 Hydraena schillhammeri Jäch, 1988
 Hydraena schmidi Jäch and Díaz, 2001
 Hydraena schoedli Jäch, 1992
 Hydraena schoenmanni Jäch, 1988
 Hydraena schubertorum Jäch and Díaz, 2001
 Hydraena schuelkei Jäch, 1992
 Hydraena schuleri Ganglbauer, 1901
 Hydraena schuleri Ganglbauer, 1901
 Hydraena scintilla Perkins, 1980
 Hydraena scintillabella Perkins, 1980
 Hydraena scintillamima Perkins, 2011
 Hydraena scintillapicta Perkins, 2011
 Hydraena scintillarca Perkins, 2011
 Hydraena scintillutea Perkins, 1980
 Hydraena scitula d’Orchymont, 1943
 Hydraena scolops Perkins, 1980
 Hydraena scopula Perkins, 1980
 Hydraena scythica Janssens, 1974
 Hydraena sepikramuensis Perkins, 2011
 Hydraena septemlacuum Jäch, 1992
 Hydraena serpentina Jäch, 1988
 Hydraena serricollis Wollaston, 1864
 Hydraena servilia Orchymont, 1936
 Hydraena sexarcuata Perkins, 2011
 Hydraena sexsuprema Perkins, 2011
 Hydraena sharmai Skale and Jäch in Jäch and Skale, 2009
 Hydraena sharpi Rey, 1886
 Hydraena shorti Perkins, 2011
 Hydraena sicula Kiesenwetter, 1849
 Hydraena sidon Jäch, Díaz and Dia in Jäch, Dia and Díaz, 2006
 Hydraena sierra Perkins, 1980
 Hydraena similis Orchymont, 1930
 Hydraena simonidea Orchymont, 1931
 Hydraena simplicicollis Blackburn, 1896
 Hydraena simplipes Zwick, 1977
 Hydraena sinope Jäch, 1992
 Hydraena smyrnensis Sahlberg, 1908
 Hydraena socius Jäch and Díaz, 1999
 Hydraena solarii Pretner, 1930
 Hydraena solodovnikovi Jäch & Díaz, 2006
 Hydraena sordida Sharp 1882
 Hydraena spangleri Perkins, 1980
 Hydraena spatula Perkins, 2011
 Hydraena speciosa Orchymont, 1944
 Hydraena spinipes Baudi, 1882
 Hydraena spinissima Perkins, 2007
 Hydraena spinobesa Perkins, 2011
 Hydraena splecoma Perkins, 1980
 Hydraena squalida Orchymont, 1932
 Hydraena stefani Jäch and Díaz, 2005
 Hydraena steineri Perkins, 2011
 Hydraena stellula Perkins, 2011
 Hydraena storeyi Perkins, 2007
 Hydraena striolata Perkins, 2011
 Hydraena stussineri Kuwert, 1888
 Hydraena subacuminata Rey, 1884
 Hydraena subgrandis Jäch, 1988
 Hydraena subimpressa Rey 1885
 Hydraena subina Orchymont, 1944
 Hydraena subinflata Orchymont, 1944
 Hydraena subinoides Orchymont, 1944
 Hydraena subintegra Ganglbauer, 1901
 Hydraena subinura Orchymont, 1944
 Hydraena subirregularis Pic, 1918
 Hydraena subjuncta Orchymont, 1930
 Hydraena sublamina Orchymont, 1945
 Hydraena sublapsa Orchymont, 1945
 Hydraena subsequens Rey, 1886
 Hydraena supersexa Perkins, 2011
 Hydraena supina Perkins, 2011
 Hydraena szechuanensis Pu, 1951
 Hydraena takin Skale and Jäch in Jäch and Skale, 2009
 Hydraena takutu Perkins, 2011
 Hydraena tarsotricha Perkins, 2011
 Hydraena tarvisina (Ferro, 1991)
 Hydraena tatii Sáinz-Cantero & Alba-Tercedor, 1989
 Hydraena tauricola Jäch, 1988
 Hydraena taxila Janssens, 1962
 Hydraena tekmanensis 
 Hydraena tenjikuana Satô, 1979
 Hydraena tenuis (Janssens, 1980)
 Hydraena tenuisella Perkins, 2007
 Hydraena tenuisoror Perkins, 2007
 Hydraena terebrans Jäch, 1992
 Hydraena terralta Perkins, 1980
 Hydraena testacea Curtis, 1830
 Hydraena tetana Perkins, 2011
 Hydraena textila Perkins, 2007
 Hydraena thienemanni Orchymont, 1932
 Hydraena thola Perkins, 2011
 Hydraena tholasoris Perkins, 2011
 Hydraena thumbelina Perkins, 2011
 Hydraena thumbelipes Perkins, 2011
 Hydraena thyene Balfour-Browne, 1958
 Hydraena tibiopaca Perkins, 2011
 Hydraena tobogan Perkins, 2011
 Hydraena torosopala Perkins, 2011
 Hydraena torricellica Perkins, 2011
 Hydraena transvallis Perkins, 2011
 Hydraena trapezoidalis Zwick, 1977
 Hydraena tricantha Zwick, 1977
 Hydraena trichotarsa Perkins, 2011
 Hydraena tricosipes Perkins, 2011
 Hydraena tridigita Perkins, 2011
 Hydraena tridisca Perkins, 2007
 Hydraena triloba Perkins, 2007
 Hydraena trinidensis Perkins, 1980
 Hydraena triparamera Jäch, 1982
 Hydraena tritropis Perkins, 2011
 Hydraena tritutela Perkins, 2011
 Hydraena truncata Rey, 1885
 Hydraena tubuliphallis Jäch, 1982
 Hydraena tucumanica Perkins, 1980
 Hydraena tuolumne Perkins, 1980
 Hydraena turcica Janssens, 1965
 Hydraena turrialba Perkins, 1980
 Hydraena tyrrhena Binaghi, 1961
 Hydraena ulna Perkins, 2011
 Hydraena umbolenta Perkins, 2011
 Hydraena unca Valladares, 1989
 Hydraena undevigintioctogintasisyphos Jäch and Díaz, 2005
 Hydraena undulata Jäch and Díaz, 1998
 Hydraena unita Perkins, 2011
 Hydraena uzbekistanica Jäch, 1994
 Hydraena vandykei Orchymont, 1923
 Hydraena variopaca Perkins, 2011
 Hydraena vedrasi d’Orchymont, 1931
 Hydraena vela Perkins, 1980
 Hydraena velvetina Perkins, 2011
 Hydraena venezuela Perkins, 2011
 Hydraena verberans Jäch and Díaz, 2006
 Hydraena verstraeteni Ferro, 1984
 Hydraena victoriae Jäch and Díaz, 1999
 Hydraena vietnamensis (Janssens, 1972)
 Hydraena virginalis Janssens, 1963
 Hydraena vodozi Sainte-Claire Deville, 1908
 Hydraena vulgaris Jäch and Díaz, 2000
 Hydraena waldheimi Jäch, 1987
 Hydraena wangi Jäch and Díaz, 1998
 Hydraena wangmiaoi Jäch and Díaz, 2005
 Hydraena watanabei Jäch and Satô, 1988
 Hydraena wattsi Perkins, 2007
 Hydraena weigeli Skale and Jäch in Jäch and Skale, 2009
 Hydraena weiri Perkins, 2007
 Hydraena wencke Skale and Jäch in Jäch and Skale, 2009
 Hydraena wewalkai Jäch, 1988
 Hydraena williamsensis Deane, 1931
 Hydraena wittmeri Satô, 1979
 Hydraena wolfi Skale and Jäch in Jäch and Skale, 2009
 Hydraena wrasei Jäch, 1992
 Hydraena xingu Perkins, 2011
 Hydraena yonaguniensis Jäch and Díaz, 2003
 Hydraena yosemitensis Perkins, 1980
 Hydraena yoshitomii Jäch and Díaz, 1999
 Hydraena youngi Perkins, 1980
 Hydraena ypsilon Zwick, 1977
 Hydraena yunnanensis Pu, 1942
 Hydraena zapatina Perkins, 1980
 Hydraena zelandica Ordish, 1984
 Hydraena zetteli Freitag and Jäch, 2007
 Hydraena zezerensis Díaz Pazos & Bilton, 1995
 Hydraena zwicki Perkins, 2007 

Waterkruipers