Hydraenidae is a family of very small aquatic beetles, sometimes called "Minute moss beetles", with a worldwide distribution. They are around 0.8 to 3.3 mm in length. The adults store air on the underside of the body as well as beneath the elytra which allows them to crawl underwater, often on the underside of the water surface tension, though they cannot swim. Some species have gills that effectively allow them to stay underwater indefinitely. Larvae vary from being fully terrestrial, to being aquatic at least in their earliest instars. The diet of hydraenid larvae and adults is thought to consist of algae, spores and other plant matter. At least some hydraenid adults use stridulation to communicate. There are around 1,300 species in 42 genera. Genera These 56 genera belong to the family Hydraenidae: Adelphydraena Perkins, 1989 Archaeodraena Jäch & Yamamoto, 2017 Aulacochthebius Kuwert, 1887 Calobius Wollaston, 1854 Cobalius Rey, 1886 Coelometopon Janssens, 1972 Davidraena Jäch, 1994 Decarthrocerus Orchymont, 1948 Discozantaena Perkins & Balfour-Browne, 1994 Edaphobates Jäch & Díaz, 2003-01 Enicocerus Stephens, 1829 Ginkgoscia Jäch & Díaz, 2004-01 Gondraena Jäch, 1994 Gymnanthelius Perkins, 1997 Gymnochthebius Orchymont, 1943 Haptaenida Perkins, 1997 Heptaenida Perkins, 1997 Homalaena Ordish, 1984 Hughleechia Perkins, 1981 Hydraena Kugelann, 1794 Hydraenida Germain, 1901 Hydroenida Germain, 1901 Hymenodes Mulsant, 1844 Laeliaena Sahlberg, 1900 Limnebius Leach, 1815 Madagaster Perkins, 1997 Menomadraena Perkins, 2017 Meropathus Enderlein, 1901 Micragasma Sahlberg, 1900 Neochthebius Orchymont, 1932 Nucleotops Perkins & Balfour-Browne, 1994 Ochtebiites Ponomarenko, 1977 Ochthebius Leach, 1815 Ochtheosus Perkins, 1997 Oomtelecopon Perkins, 2005 Orchymontia Broun, 1919 Parasthetops Perkins & Balfour-Browne, 1994-31 Parhydraena Orchymont, 1937 Parhydraenopsis Perkins, 2009-16 Phothydraena Kuwert, 1888 Pneuminion Perkins, 1997 Podaena Ordish, 1984 Prionochthebius Kuwert, 1887 Prosthetops Waterhouse, 1879 Protochthebius Perkins, 1997 Protosthetops Perkins, 1994 Protozantaena Perkins, 1997 Pterosthetops Perkins, 1994 Sebasthetops Jäch, 1998-01 Sicilicula Balfour-Browne, 1958 Spanglerina Perkins, 1980 Trinomadraena Perkins, 2017 Tympallopatrum Perkins, 1997 Mesoceration Janssens, 1967 Parhydraenida Balfour-Browne, 1975 Tympanogaster Janssens, 1967 Extinct genera †Archaeodraena Jäch and Yamamoto 2017, Burmese amber, Myanmar, Late Cretaceous (Cenomanian) †Ochtebiites Ponomarenko 1977 Abasheva Formation, Russia, Early Jurassic (Pliensbachian), Ichetuy Formation, Russia, Karabastau Formation, Kazakhstan, Late Jurassic (Oxfordian), Mogotuin Formation, Mongolia, Early Cretaceous (Aptian) References External links Hydraenidae, Identification and Ecology of Australian Freshwater Invertebrates. Hydraenidae at Tolweb Staphylinoidea Beetle families