Dryopidae

Dryops ernesti

The Dryopidae, German (together with the closely related Elmidae ) often referred to as hooks or claws beetle beetles, are a family of beetles. The species live partly in water, some in moist habitats and riparian zones ( " riparisch " ) on land. The family includes about 250 species in Central Europe, 13 species in two genera.

Features

Dryopidae are between a good and just ten millimeters long, hard sclerotized and usually black or dark brown colored beetles. Rarely, the elytra on shiny metallic blue or green tones or red spots, usually the body appendages (legs, antennae, mouthparts ) are brightened somewhat, often reddish brown or reddish. The body is often nearly glabrous or hairy little flashy, but can carry a dense and stiff pubescence of short erect hairs in some genera. The belly helps the aquatic representatives of an extremely dense and very short, with the naked eye visible hairs, which maintains an air film, which is used for breathing underwater ( plastron respiration ). The body outline is usually compact, more or less flattened oval, the head partially retracted into the pronotum, the mouthparts are facing down ( hypognath ).

Typical of the family and distinctive feature of the Elmidae is the construction of the sensor. These are usually very short and consist of a relatively small base member, a very large, mostly asymmetrically unilaterally expanded second member and a relatively short, one-sided sawn sensor lobe from nine to eleven members, the length of which barely exceeds that of the second member. Variations of this basic form occur in some genera. Thus, the antenna of Ceradryops is tripartite, the six members of Uenodryops. Wherein the first segment extends Holcodryops instead of the second. Mostly, the head below the antennae pits into which they can be inserted.

The pronotum often has longitudinal grooves or longitudinal keels, sometimes the elytra. The elytra extend to the end of the abdomen, they are usually pulled something together pointed to the rear. On its top point strips are usually trained, sometimes in furrows. Most species have fully developed hind wings and are well capable of flight, a number of non airworthy species with shortened wings before coming. The most powerful legs have five-membered tarsi, the last member is club-shaped enlarged and taken together is greater than the first four. At this sits a pair of sharp, long claws. The Coxen ( hips ) of the rear legs can be inserted under platy projections ( leg ceilings). The legs ( femurs ) are hollowed out in the rule so that the rails can be inserted into this recess. The abdomen has the ventral side on five visible sternites, of which the first four are moved close to each other and connected to each other without joint membrane.

It is characterized by the construction of the female genitalia. These are transformed into a two-part, highly elongated, often pike -like appendage, which probably serves as ovipositor to lay eggs in muddy banks or plant tissue. It could reach in an extended state, the length of the abdomen.

Larvae

Larvae Dryopidae are more or less elongated cylindrical in shape with a circular outline and the body relatively short legs. They are hard sclerotized and reddish, sometimes yellow to brown, colored, often with dark circles or dark drawing. Its length is about 7 to 12 millimeters. The head is partially retracted into the fuselage, the mouthparts facing forward ( prognathous ). On the sides of the head usually sit six button-shaped larval eyes ( stemmata ) which may also be missing. The abdomen consists of nine segments, the posterior are fused ring. On the ninth segment is located on the ventral side, a lid (operculum ) with two hook-like attachments ( limb rudiments ). In contrast to the Elmidae the larvae of Dryopidae do not have gills, they are air breathing with open spiracles.

Dolls

Dolls of the Dryopidae are known only from a few species. These are elongated, hairy and whitish colored with relatively soft cuticle. In most classes, the rear end is drawn out into a spine or thread. Noteworthy are dark and heavily sclerotized, clip-like extensions on the dorsal side, as "gin traps" (engl: Fang iron) are known, these are movable by muscles. They may serve for defense, but more likely for clamping in the doll chamber.

Way of life

The Dryopidae live as Imagines either in water or in moist habitats on land, usually in the riparian zone of waters. The larvae are in all cases, country living ( or terrestrial). Inhabited by both stationary as well as moving water, often including very small with temporary water management. In contrast to the Elmidae the beetles are but mostly shunning flow in rivers and prefer quiet bays and the littoral zone. Some genera, such as Helichus can also occur in fast flowing areas. Many species of the riparian zone to live temporarily submerged in the water, some on land and change his life between these habitats back and forth.

The life cycle and biology of most species are poorly understood. At least some species require several years for larval development. Both the beetles and their larvae feed, if known, of soft plant debris ( detritus ) and algae.

System

The Dryopidae include a number of related, all of them living in the water or in very moist habitats families in a lineage within the superfamily Byrrhoidea. The group was conceived as a separate superfamily Dryopoidea. The phylogeny of this group is still unclear. Closest related and possible sister group might be just the anatomy, especially the larvae, the family Limnichidae.