Agabus is a large genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of predatory aquatic

Aquatic insects

Aquatic insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.-Breathing:...

 beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s in the family Dytiscidae

Dytiscidae

Dytiscidae – based on the Greek dytikos , "able to dive" – are the predaceous diving beetles, a family of water beetles. They are about 25 mm long on average, though there is much variation between species. Dytiscus latissimus, the largest, can grow up to 45 mm long...

, proposed in 1817 by William Elford Leach

William Elford Leach

William Elford Leach FRS was an English zoologist and marine biologist.Leach was born at Hoe Gate, Plymouth, the son of a solicitor. At the age of twelve he went to school in Exeter, studying anatomy and chemistry. By this time he was already collecting marine samples from Plymouth Sound and along...

 and named after Agabus

Agabus

Saint Agabus or Saint Agabo was an early follower of Christianity mentioned in the Acts of the Apostles as a prophet. He is traditionally remembered as one of the Seventy Disciples described in Luke ....

, an early follower of Christianity. The adult beetles are moderate-sized, 5 to 14 mm long. The genus is primarily Holarctic

Holarctic

The Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...

 in distribution, with only a few species known from the Afrotropic

Afrotropic

The Afrotropic is one of the Earth's eight ecozones. It includes Africa south of the Sahara Desert, the southern and eastern fringes of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the islands of the western Indian Ocean. It was formerly...

 and Neotropic realms. Three species of Agabus, namely A. clypealis

Agabus clypealis

Agabus clypealis is a species of beetle in family Dytiscidae. It can be found in Denmark, Germany, Latvia, Poland, Russia, and Sweden.-References:* Foster, G. 1996. . Downloaded on 9 August 2007....

, A. discicollis

Agabus discicollis

Agabus discicollis is a species of beetle in family Dytiscidae. It is endemic to Ethiopia.-References:* Foster, G. 1996. . Downloaded on 9 August 2007....

and A. hozgargantae

Agabus hozgargantae

Agabus hozgargantae is a species of beetle in family Dytiscidae. It is endemic to Spain.-References:* Foster, G. 1996. . Downloaded on 9 August 2007....

are endangered

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 according to the IUCN Red List

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

. The division into subgenera is not widely accepted. However, a number of species group

Species group

A species group is an informal taxonomic rank into which an assemblage of closely related species within a genus are grouped because of their morphological similarities and their identity as a biological unit with a single monophyletic origin.-Use:...

s are recognized after the works of David J. Larson and Anders N. Nilsson. The genus is probably polyphyletic or paraphyletic. In a recent study of mitochondrial DNA

Mitochondrial DNA

Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...

, Agabus was found paraphyletic with respect to several of the species groups of Platambus

Platambus

Platambus is a genus of beetle native to the Palearctic, including Europe, the Near East and North Africa. It destingushed by a wide epipleuron. Ventral body part, as a fact, has spot marking.-External links:*...

, a closely related genus in the tribe Agabini. Lately the taxonomy of the genus has been revised, and some groups of species were transferred from Agabus sensu stricto to other genera in the tribe Agabini.

Further reading

Hilsenhoff, W.L. (1986) Life history strategies of some Nearctic Agabini (Coleoptera, Dytiscidae). Entomologica Basiliensia 11: 385-390.

Larson D.J. (1989). Revision of North American Agabus Leach (Coleoptera: Dytiscidae): introduction, key to species groups, and classification of the ambiguus-, tristis- and arcticus-groups. The Canadian Entomologist 121: 861-919.

Larson D.J. (1991). Revision of North American Agabus Leach (Coleoptera: Dytiscidae): elongatus-, zetterstedti-, and confinis-groups. The Canadian Entomologist 123: 1239-1317.

Larson D.J. (1994). Revision of North American Agabus Leach (Coleoptera: Dytiscidae): lutosus-, obsoletus-, and fuscipennis-groups. The Canadian Entomologist 126: 135-181.

Larson D.J. (1996). Revision of North American Agabus Leach (Coleoptera: Dytiscidae): the opacus-group. The Canadian Entomologist 128: 613-665.

Larson D.J. (1997). Revision of North American Agabus Leach (Coleoptera: Dytiscidae): the seriatus-group. The Canadian Entomologist 129: 105-149.

Larson D.J., Alarie Y., Roughley R.E. (2000) Predaceous diving beetles (Coleoptera: Dytiscidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska. Ottawa: NRC Research Press. ISBN 0660179679.

Larson, D.J. & Nilsson, A.N. (1985) The Holarctic species of Agabus (sensu lato) Leach (Coleoptera: Dystiscidae). The Canadian Entomologist 117: 119-130.

Larson D.J. & Wolfe R.W. (1998). Revision of North American Agabus (Coleoptera: Dytiscidae): the semivittatus-group. The Canadian Entomologist 130: 27-54.

Nilsson, Anders N. (1982). A key to the identification of the known third-stage larvae of the Fennoscandian species of the genus Agabus (Coleoptera: Dytiscidae). Entomologica Scandinavica 13 (3): 333-338.

Nilsson, Anders N. (1986) Life cycle and habitats of the northern European Agabini (Coleoptera: Dytiscidae). Entomologica Basiliensia 11: 391-417, 1986.

Nilsson, Anders N. (1987) A key to the first instar larvae of Fennoscandian Agabus Leach (Coleoptera, Dytiscidae). Fauna Norvegica, Series B 34 (2): 131-137.

Nilsson, Anders N. (1992) A revision of Afrotropical Agabus Leach (Coleoptera, Dytiscidae), and the evolution of tropicoalpine super specialists. Systematic Entomology

Systematic Entomology

Systematic Entomology is a scientific journal covering the field of systematic entomology, published by the Royal Entomological Society of London. Having begun in 1932 as Proceedings of the Royal Entomological Society of London, Series B: Taxonomy, the title was changed to ournal of Entomology,...

17 (2), 155-179.

Nilsson, Anders N. (2000) A new view on the generic classification of the Agabus-group of genera of the Agabini, aimed at solving the problem with a paraphyletic Agabus (Coleoptera: Dytiscidae). Koleopterologische Rundschau 70: 17–36.

External links

• Genus Agabus Leach, 1817 (Coleoptera, Dytiscidae) (atlas of beetles of Russia)