~70 spp. in 6 genera of 2 subfamilies in our area, 210 spp. in the New World, ~1400 described spp. (+hundreds undescribed) in >40 genera worldwide(1)(2)(3)(4)(5)(6) (the cosmopolitan Hydraena alone includes ~900 described spp.)
not yet in the guide: Enicocerus (regarded as subgenus of Ochthebius by some workers)
in moss or accumulations of moist/wet dead leaves and sticks/twigs along the margins of streams, rivers, sinkholes, pools and ponds; also in littoral zone substrata(7)
Food
Larvae and adults graze on wet stones, sand grains and plant matter, where they feed on algae, bacteria, protozoans and detritus(7)
Remarks
Some of the oldest beetle fossils are hydraenids, from the lower Jurassic(1)
See Also
The antennal club of 5 antennomeres (vs normally 3 antennomeres in hydrophiloids)(1)