Hydraenidae Temporal range: Early Jurassic–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Staphyliniformia
Superfamily:	Staphylinoidea
Family:	Hydraenidae Mulsant, 1844
Subfamilies
Hydraeninae Mulsant, 1844 Ochthebiinae C. G. Thomson, 1860 Orchymontiinae Perkins, 1997 Prosthetopinae Perkins, 1994

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.^[1]

Genera

These 56 genera belong to the family Hydraenidae:^[2][3][4]

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)