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.
Carabdytes alutaceus is an endangered species of beetle in the family Dytiscidae. It is endemic to New Caledonia, in the southwest Pacific Ocean.
Rhantus is a genus of beetle in family Dytiscidae. There are about 100 species distributed worldwide. They often live in pools and marshy habitat types. Several species have colonized oceanic islands and become endemics.
Meridiorhantus orbignyi is an extinct species of predaceous diving beetle in the family Dytiscidae. This species was formerly a member of the genus Rhantus.
Matus is a genus of beetle in family Dytiscidae from North America. It contains the following species:
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.
Coptotomus is a genus of predaceous diving beetles in the family Dytiscidae, the only genus of the subfamily Coptotominae. There are about six described species in Coptotomus, found in North America and the Neotropics.
Batrachomatus is a genus of beetles in the family Dytiscidae, containing the following species:
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.
Carabdytes plantaris is a naturally uncommon species of diving beetle in the family Dytiscidae. It is endemic to New Zealand. For over a century, it was known from just a single specimen collected in 1880 "near Dunedin", and doubts were cast on whether it was actually a New Zealand species at all. In 1986, it was rediscovered when several were collected from a roadside pond near Lake Ellesmere. Carabdytes plantaris is now classed as "naturally uncommon" by the Department of Conservation.
Nartus grapii is a species of beetle in family Dytiscidae, found in the Palearctic. This species was formerly a member of the genus Rhantus.
Rhantus frontalis is a species of predaceous diving beetle in the family Dytiscidae. It is found in Europe & Northern Asia and North America.
Nartus sinuatus 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.
Rhantus suturellus is a species of predaceous diving beetle in the family Dytiscidae. It is found in North America and the Palearctic.
Rhantus gutticollis is a species of predaceous diving beetle in the family Dytiscidae. It is found in North America and the Neotropics.
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.
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.
