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.
Megadytes is a genus of diving beetles in the family Dytiscidae. They are found in slow-moving or static freshwater habitats throughout most of the Neotropics, ranging from Florida and Mexico, through the West Indies and Central America, to South America as far south as central Argentina. The adult beetles measure about 1.65–4.75 cm (0.6–1.9 in) long depending on the exact species and the largest is also the largest in the family.
Meridiorhantus orbignyi is an extinct species of predaceous diving beetle in the family Dytiscidae. This species was formerly a member of the genus Rhantus.
Carabdytes is a genus of predaceous diving beetles in the family Dytiscidae. Carabdytes upin was formerly the sole species of this genus, but nine species in the genus Rhantus were transferred to Carabdytes as a result of research published by Balke et al. in 2017.
Meridiorhantus calidus is a species of predaceous diving beetle in the family Dytiscidae. It is found in North America and the Neotropics. This species was formerly a member of the genus Rhantus.
Bidessini is a tribe of predaceous diving beetles in the family Dytiscidae. There are at least 40 genera and at least 630 described species in Bidessini.
Nartus sinuatus Black with dark rufous legs; posterior margin of pronotum arched just before hind angles(3) is a species of predaceous diving beetle in the family Dytiscidae, found in North America. This species was formerly a member of the genus Rhantus.
Colymbetini is a tribe of predaceous diving beetles in the family Dytiscidae. There are about 11 genera and more than 160 described species in Colymbetini.
Colymbetinae is a subfamily of predaceous diving beetles in the family Dytiscidae. There are about 11 genera and at least 130 described species in Colymbetinae.
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.
Coptotomus loticus is a species of predaceous diving beetle in the family Dytiscidae. It is found in North America.
Hydrodytinae is a subfamily of predaceous diving beetles in the family Dytiscidae. There are at least two genera and four described species in Hydrodytinae.
Liadytiscinae is a subfamily of extinct predaceous diving beetles in the family Dytiscidae. There are about 5 genera and 10 described species in Liadytiscinae. All currently known members of the subfamily are known from the Early Cretaceous Jehol Biota of China.
Madaglymbus is a genus of predaceous diving beetles in the family Dytiscidae. There are about 15 described species in Madaglymbus. They are found in Africa.
Boreonectes is a genus of predaceous diving beetles in the family Dytiscidae. There are about 16 described species in Boreonectes. They are found in North America, the Neotropics, and the Palearctic.
Brancuporus is a genus of predaceous diving beetles in the family Dytiscidae. There are at least two described species in Brancuporus. They are found in Australasia.
Neobidessodes is a genus of predaceous diving beetles in the family Dytiscidae. There are about 10 described species in Neobidessodes. They are found in Australasia. The genus was first described in 2009, and the type species is N. denticulatus.
Meridiorhantus is a genus of predaceous diving beetles in the family Dytiscidae. There are about five described species in Meridiorhantus, found in the Neotropics and North America. These species were formerly members of the genus Rhantus, but were moved to Meridiorhantus when it was created by Balke et al. in 2017.
Caperhantus is a genus of predaceous diving beetles in the family Dytiscidae. There is one described species in Caperhantus, C. cicurius. This species was formerly a member of the genus Rhantus.
Nartus is a genus of predaceous diving beetles in the family Dytiscidae. There are at least two described species in Nartus. These species were formerly members of the genus Rhantus, but were moved to Nartus when it was reinstated by Balke et al. in 2017.
