The Dytiscidae – based on the Greek dytikos (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live among leaf litter. The adults of most are between 1 and 2.5 cm (0.4–1.0 in) long, though much variation is seen between species. The European Dytiscus latissimus and Brazilian Megadytes ducalis are the largest, reaching up to 4.5 cm (1.8 in) and 4.75 cm (1.9 in) respectively. In contrast, the smallest is likely the Australian Limbodessus atypicali of subterranean waters, which only is about 0.9 mm (0.035 in) long. Most are dark brown, blackish, or dark olive in color with golden highlights in some subfamilies. The larvae are commonly known as water tigers due to their voracious appetite. They have short, but sharp mandibles and immediately upon biting, they deliver digestive enzymes into prey to suck their liquefied remains. The family includes more than 4,000 described species in numerous genera.
Ilybius is a large genus of predatory aquatic beetles in the family Dytiscidae. The genus is native to the Palearctic, the Near East, the Nearctic, and North Africa. 70 species has been described from this genus:
Hydroporus is a genus of water beetles native to the Palearctic, the Nearctic, the Near East, and North Africa. It contains the following species:
Neoclypeodytes is a genus of beetles in the family Dytiscidae, containing the following species:
Desmopachria is a genus of beetles in the family Dytiscidae, containing the following species:
Celina is a genus of predaceous diving beetles in the family Dytiscidae. There are at least 30 described species in Celina.
Berosus is a genus of beetles in the family Hydrophilidae, the water scavenger beetles. The genus contains 273 species. It is distributed worldwide.
Tropisternus is a genus of hydrophilid beetles with 63 species in five subgenera in North and South America.
Cymbiodyta is a genus of hydrophilid beetles with 31 species. Twenty–eight of the species occur in the Americas and three species in the Palearctic.
Deltostethus is a genus of water scavenger beetles in the family Hydrophilidae. There are at least four described species in Deltostethus.
Eulimnichus is a genus of minute marsh-loving beetles in the family Limnichidae. There are more than 30 described species in Eulimnichus.
Laccobius is a genus of water scavenger beetles in the family Hydrophilidae. There are more than 80 described species in Laccobius.
Sericoderus is a genus of minute hooded beetles in the family Corylophidae. There are about 12 described species in Sericoderus.
Hyphydrini is a tribe of predaceous diving beetles in the family Dytiscidae. There are about 16 genera and more than 390 described species in Hyphydrini.
Lichnanthe is a genus of bumble bee scarab beetles in the family Glaphyridae. There are about 10 described species in Lichnanthe.
Litargus is a genus of hairy fungus beetles in the family Mycetophagidae. There are at least 20 described species in Litargus.
Pycnomerus is a genus of ironclad beetles in the family Zopheridae. There are more than 20 described species in Pycnomerus.
Monotominae is a subfamily of root-eating beetles in the family Monotomidae. There are about 10 genera and more than 80 described species in Monotominae.
Coelostomatini is a tribe of water scavenger beetles in the family Hydrophilidae. There are about 7 genera and more than 70 described species in Coelostomatini.
Larainae is a subfamily of riffle beetles in the family Elmidae. There are more than 20 genera and 160 described species in Larainae.
