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).^[1][2]

Quick Facts Scientific classification, Species ...

Helophorus Temporal range: Late Jurassic–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Helophorus aquaticus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Infraorder:	Staphyliniformia
Superfamily:	Hydrophiloidea
Family:	Helophoridae Leach, 1815
Genus:	Helophorus Fabricius, 1775
Species
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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).^[3]

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.^[4]

Helophoridae belong to the superfamily Hydrophiloidea, and may be the sister taxon of Hydrochidae,^[5] or a clade comprising Hydrochidae, Hydrophilidae and Spercheidae or Georissidae and Epimetopidae.^[6] 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.^[7]

There are about 180 living species, including: