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Family Dytiscidae - Predaceous Diving Beetles

Dytiscid? - Hydroporus striola Dytiscidae 01a - Acilius abbreviatus - male - female Predaceous Diving Beetle - Graphoderus occidentalis - female Predaceous Diving Beetle - Agabus antennatus - female Acilius? - Acilius semisulcatus Agabus strigulosus Crotch - Agabus strigulosus Hydroporus columbianus Fall - Hydroporus columbianus - male Air Dropped Water Beetle - Acilius mediatus - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Adephaga (Ground and Water Beetles)
Family Dytiscidae (Predaceous Diving Beetles)
Other Common Names
Predacious Diving Beetles (spelling)
Numbers
White, p. 97, lists 41 genera, 476 species (1)

Classification of Nearctic Dysticidae (Adapted from Larson et al. 2000)
*Guide pages for tribes are not included in the guide at this time*

Subfamily Copelatinae Van den Branden 1885
Copelatus Erichson 1832

Agaporomorphus Zimmerman 1921

Subfamily Hydrotrupinae Roughley
Hydrotrupes Sharp 1882

Subfamily Agabetinae Van Der Branden 1885
Agabetes Crotch 1873

Laccophilus Leach 1817

Laccodytes Regimbart 1895

Subfamily Hydroporinae Erichson 1837
Tribe Methlini Van Der Branden 1885
Celina Aube 1837

Tribe Hydrovatini Sharp 1837
Hydrovatus Motschulsky 1853
Tribe Bidessini Sharp 1882
Comaldessus Spangler and Barr 1995

Uvarus Guignot 1939

Brachyvatus Zimmerman 1919
Andocheilus Babington 1841
Bidessonotus Regimbart 1895

Crinodessus Miller 1997
Neoclypeodytes Young 1967
Neobidessus Young 1967

Liodessus Guignot 1939

Tribe Laccornini Wolfe and Roughley 1990
Laccornis Gozis 1914

Tribe Hyphydrini Sharp 1882
Desmopachria Babington 1841

Pachydrus Sharp 1882
Tribe Hydroporinae Erichson 1837
Haedeoporus Young and Longley 1976
Stygoporus Larson and LarBonte 1994
Hygrotus Stephens 1839

Hydroporus Clairville 1806

Neoporus Guignot 1931

Sanfilippodytes Franciscolo 1979

Hydrocolus Roughley & Larson 2000

Lioporeus Guignot 1950
Heterosternuta Strand 1935

Oreodytes Seidlitz 1887

Nebrioporus Regimbart 1906

Stictotarsus Zimmerman 1837


Subfamily Colymbetinae Erichson 1837
Tribe Matini Van Der Branden 1885
Matus Aube 1836

Tribe Coptotomini Van der Branden 1885
Coptotomus Say 1885

Tribe Agabini Thomson 1867
Agabinus Crotch 1873
Carrhydrus Fall 1923

Agabus Leach 1817

Ilybius Erichson 1832

Tribe Colymbetini Erichson 1837
Colymbetes Clairville 1806

Neoscutopterus Balfour-Browne 1943
Hoperius Fall 1927
Rhantus Dejean 1883


Tribe Dytiscini Leach 1817
Dytiscus Linnaeus 1758

Tribe Acilini Thomson 1867
Acilius Leach 1817

Thermonectus Dejean 1837

Graphoderus Dejean 1833

Tribe Hydaticini Sharp 1882
Hydaticus Leach 1817

Tribe Cybistrini Sharp 1882
Megadytes Sharp 1882
Cybister Curtis 1827

Tribe Eretini Crotch 1873
Eretes Laporte 1833
Size
body length 1.2-40 mm
Identification
Aquatic beetles whose hind tibiae have long hairs, other modifications for swimming. Dytiscids move their legs together like oars, in the manner of Backswimmers in the Hemiptera. In other aquatic beetle families, such as the Hydrophilidae, the legs are moved alternately. (2)
In much of the eastern United States, the only two very large (25-35 mm) members of this family are Dytiscus and Cybister. They are similar, but several characters can be used to separate them. (3) (4)
  • Lower/outer hind tibial spur much wider than upper/inner in Cybister, spurs similar in size in Dytiscus.
  • Metatibia of Cybister is short and broad, that of Dytiscus is longer and narrower.
  • Prosternum of Cybister is greenish, that of Dytiscus is reddish.
  • Structure of adhesive pads on male protarsi differs between the two genera. Dytiscus has two larger circular disks on with adjacent smaller ones. Cybister has a longer, broader pad. This is shown nicely in figure 33 of White. (1)
  • On metatarsi, outer margin of Cybister has a narrow fringe, lacking in Dytiscus.
  • Females of Cybister have long lengthwise scratches on elytra, lacking deep furrows found on some female Dytiscus.
  • Male Dytiscus tends to have prominent rows of punctures on elytra, weak in Cybister.
Range
Much of North America.
See Also
Water Scavenger Beetles (Hydrophilidae)
Print References
White, pp. 96-100 (1)
Papp, pp. 60-62, discusses locomotion, has good discussion of family characters, including those of larvae (2).
Dillon, pp. 132-154 (3)
Ciegler, pp. 41-89, extensive keys (4)
America Beetles, Vol. 1, Chapter 12 (5)
Castner, pp. 112-113, has representative photos, comparing with other aquatics. (6)
Arnett et al. pp. 108-114 (7)
D.J. Larson, Y. Alarie, and R.E. Roughley, Predaceous Diving Beetles (Coleoptera: Dytiscidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska(8) keys to all species, with descriptions and distribution maps for those found in Canada (which covers many also found in the lower 48 US)
Internet References
preserved adult images of 46 species with descriptions, distribution, habitat, and biology of each (Charles Staines, Discover Life in America, dlia.org)
Univ. Florida--ENY 3005
Aquatic Invertebrates of Alberta - Beetles General info, keys to familes and genera, and several dozen photos