Dryopidae is a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s, commonly named long-toed water beetles, in the superfamily
Byrrhoidea
Byrrhoidea is a superfamily of beetles belonging to Elateriformia that includes several families which are either aquatic or associated with a semi-aquatic habitat. Other than the superfamily Hydrophiloidea, most of the remaining Polyphagan beetle ...
. It was described by
Gustaf Johan Billberg
Gustaf Johan Billberg (14 June 1772, Karlskrona – 26 November 1844, Stockholm) was a Swedish botanist, zoologist and anatomist, although professionally and by training he was a lawyer and used science and biology as an avocation. The plant genu ...
in 1820.
Description
Long-toed water beetles are named for their extended claws. Adults have dense hairs, which allow the beetles to breathe while underwater. The flight muscles of the females weaken as they age.
When the
pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
e complete the
imago
In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
stage of their life cycle, they move towards running water, and may be attracted to lights.
Despite being referred to as
aquatic insects, the beetles are unable to swim,
clinging to
detritus
In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...
that float. All long-toed water beetles feed on plants that are in the water, but the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e generally are
terrestrial, and at least some also feed on plant matter. ''
Stygoparnus
''Stygoparnus'' is a monotypic genus[''Stygoparnus''.]
BugGuide.net of Genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
of the family closely resemble
riffle beetles, but the
antennae are different from the long-toed water beetles, looking similar to clubs.
Habitat
Members of this family are found on every continent, except Antarctica and Australia, being more common in the
tropics
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
. In 2005, a possible fossilized specimen of Dryopidae was found in the
Crato Formation by entomologists
David Grimaldi and
Michael S. Engel.
Beetles that have water as a habitat, including long-toed water beetles, can help show the quality of
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
.
Genera
* ''
Ahaggaria''
Bollow, 1938
* ''
Ceradryops''
Hinton, 1937
* ''
Drylichus''
Heller, 1916
* ''
Dryops''
Olivier, 1791
* ''
Elmomorphus''
Sharp, 1888
* ''
Elmoparnus''
Sharp, 1882
* ''
Geoparnus''
Besuchet, 1978
* ''
Guaranius''
Spangler, 1991
* ''
Helichus
Beetles of the genus ''Helichus'' are found worldwide apart from in Australia and Antarctica. Adults reach long and live in aquatic or riparian environments. The larvae are land-dwelling which may be unique in water living insects.
Species
Thes ...
''
Erichson, 1847
* ''
Holcodryops''
Spangler, 1987
* ''
Malaiseianus''
Bollow, 1940
* ''
Onopelmus''
Spangler, 1980
* ''
Oreoparvus''
Delève, 1965
* ''
Pelonomus''
Erichson, 1847
* ''
Phallodryops''
Delève, 1963[
]
* ''
Postelichus''
Nelson, 1989
* ''
Protoparnus''
Sharp, 1883
* ''
Pseudopelonomus''
Brown, 1981
* ''
Quadryops''
Perkins & Spangler, 1985
* ''
Rapnus''
Grouvelle, 1899
* ''
Sostea''
Pascoe, 1860
* ''
Sosteamorphus''
Hinton, 1936
* ''
Strina''
Redtenbacher, 1867
* ''