Common name: Water scavenger beetles
Number of species: 20
Size Range: 2-7mm
Tarsi: 5-5-5.
Description:
One British genus, Helophorus, with 20 species. Small (2-7mm) elongate beetles, with the body outline constricted between the elytra and pronotum, they have long palps, similar in size to their antennae and 7 longitudinal grooves on the coarsely-granulate pronotum. The genus is characteristic of impermanent ponds, often ephemeral pools on grassland, although a few species are associated with dry ground. Dissection of males is very useful for reliable ID.
Where do giant water scavenger beetles live?
These beetles are found swimming in marshy freshwater ponds throughout the world, especially in warm regions. Water scavenger beetles have smooth, oval, dark brown or black bodies and short, hairy, clubbed antennae.
How big are water scavenger beetles?
1-1/2 inch
They range in size up to 1-1/2 inch (40 mm). Larvae may be up to 2-3/8 inches (60 mm) long. Their jaws (mandibles) are usually toothed. The abdomen often has a wrinkled appearance and often has long filaments extending from the sides (some predaceous diving beetles also have filaments).
What is the Japanese water scavenger beetle?
Regimbartia attenuata, commonly known as Japanese water scavenger beetle, is a species of water scavenger beetle widely distributed in the Old World, from northern Australia and Japan westward to the countries of Arabian Peninsula, including Oman and Yemen.
Helophorus is the only genus in the beetle family Helophoridae (traditionally included within Hydrophilidae as the subfamily Helophorinae) within the Hydrophiloidea. They are small insects, found mainly in the Holarctic region (150 occur in Palearctic and 41 species in North America), but two or three species also live in the Afrotropical region, Central America and one in the Indomalayan region (northern India).
Characteristics
Length about 2–9 mm. Body elongate with outline more or less interrupted between pronotum and elytra. On pronotum they have granulate sculpture and unique pattern of 7 longitudinal grooves. Ventral surface is with fine microsculpture, pubescent. Larvae are with long 3 segmented urogomphi and simple (non lobate) 8th tergum. They have four-segmented legs and a 10 segmented abdomen (with the 10th segment being a bit reduced).
Ecology
The majority of Helophorus species adults are aquatic live on the periphery of rivers and streams as well as stagnant bodies of water or pools, though a number are also terrestrial. Adults generally feed on decaying plant material, though some are known to feed on living plant tissue, with several species noted as pests of turnips. The larvae are terrestrial and are predominantly carnivores, though in some species are herviorous, and are pests of turnips, rutabaga, and wheat.
Systematics and evolution
Helophoridae belong to the superfamily Hydrophiloidea, and may be the sister taxon of Hydrochidae, or a clade comprising Hydrochidae, Hydrophilidae and Spercheidae or Georissidae and Epimetopidae. Earlier systems included all of these families in the family Hydrophilidae. The genus is divided into many subgenera (Atracthelophorus, Cyphelophorus, Empleurus, Eutrichelophorus, Gephelophorus, Helophorus, Orphelophorus, Rhopalohelophorus and Transithelophorus). The oldest fossils of Helophorus are from the Late Jurassic of Asia, with the major clades of extant Helophorus likely diverging from each other during the Early Cretaceous.
Beetles represent the largest insect group with around 4,000 species in Britain and 300,000 worldwide. They are easy to recognise as their front wings are hard, covering the second pair of wings and the abdomen. All beetles have biting mouthparts. The beetle species in this gallery are grouped into families which are presented in taxonomic order according to the Checklist of Beetles of the British Isles (Duff 2012).
Helophorus ís the only genus in the beetle family Helophoridae (traditionally included within Hydrophilidae as the subfamily Helophorinae). They are small insects, found mainly in the Holarctic region (150 occur in Palearctic and 41 species in North America), but two or three species also live in the Afrotropical region, Central America and one in the Indomalayan region (northern India).
