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.
Graphoderus is a genus of beetle in family Dytiscidae native to the Holarctic.
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.
Acilius is a holarctic genus of diving beetles in the family Dytiscidae and typically has a life cycle that is univoltine.
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.
Aethionectes is a genus of beetles in the family Dytiscidae found in sub-Saharan Africa and Madagascar.
Sandracottus is a genus of beetles in the family Dytiscidae. These aquatic beetles are found in ponds and slow streams from South Asia east to southern Japan, and south to Australia. They are generally about 1–1.5 cm (0.4–0.6 in) long and often have distinctive markings.
Tikoloshanes eretiformis is a species of beetle in the family Dytiscidae, the only species in the genus Tikoloshanes. This species has rarely been collected and is known only from South Africa and southern Mozambique.
Notaticus is a genus of beetles in the family Dytiscidae and the only genus in the tribe Aubehydrini. The genus is distributed in the lowland tropical areas of South America from Venezuela to Bolivia. The genus contains these two species:
Austrodytes is a genus of beetles in the family Dytiscidae found only in northern Australia. The genus contains these two species:
Onychohydrus is a genus of beetles in the family Dytiscidae. The genus is found in Australia, Tasmania, and New Zealand's North Island. The genus consists of these two species:
Regimbartina pruinosa is a species of beetle in the family Dytiscidae, the only species in the genus Regimbartina. The known distribution of the species is in Cameroon, Angola, and Gabon.
Spencerhydrus is a genus of beetles in the family Dytiscidae. The genus is found only in southern Australia and contains the following two species:
Sternhydrus is a genus of beetles in the family Dytiscidae. They are found in Australia, New Guinea, and Buru Island. The genus contains the following four species:
Copelatus marginipennis is a species of diving beetle. It is part of the genus Copelatus in the subfamily Copelatinae of the family Dytiscidae. It was described by Laporte in 1835.
Madaglymbus apicalis is a species of diving beetle. It is part of the genus Madaglymbus in the subfamily Copelatinae of the family Dytiscidae. It was described by Fairmaire in 1898. Madaglymbus apicalis is distributed along the coastlines of much of Africa.
Copelatus haemorrhoidalis is a species of diving beetle. It is part of the genus Copelatus in the subfamily Copelatinae of the family Dytiscidae. It was described by Régimbart in 1883.
Exocelina subjecta is a species of diving beetle. It is part of the genus Exocelina in the subfamily Copelatinae of the family Dytiscidae. It was described by David Sharp in 1882.
Exocelina cheesmanae is a species of diving beetle. It is part of the genus Exocelina in the subfamily Copelatinae of the family Dytiscidae. It was described by J. Balfour-Browne in 1939.
