Helophorus Fabricius, 1775

Fikáček, Martin, Prokin, Alexander, Angus, Robert B., Pono, Alexander, Marenko, Yue, Yanli, Ren, Dong & Prokop, Jakub, 2012, Revision of Mesozoic fossils of the helophorid lineage of the superfamily Hydrophiloidea (Coleoptera: Polyphaga), Acta Entomologica Musei Nationalis Pragae 52 (1), pp. 89-127 : 103

Helophorus Fabricius, 1775

Type species. Silpha aquatica Linnaeus, 1758 (= Helophorus (s. str.) aquaticus (Linnaeus, 1758) (modern)), designated by LATREILLE (1810).

Time range. Late Jurassic (ca. 150–146 mya) to recent.

Diagnosis. Adult: Head and pronotum at least partly with setiferous granules in most species (granulation totally reduced in few species only); frontoclypeal suture very distinct, its median portion grooved; mentum distinctly transverse or only slightly wider than long; gula usually strongly constricted (moderately wide with well-separated gular sutures in few species only); pronotum with one to five longitudinal grooves (if less than five grooves are present, then all pronotal intervals bear large and very distinct setiferous granules); lateral margin of pronotum at least slightly crenulate; anterolateral portion of hypomeron with antennal groove; mesanepisterna not meeting mesally; mesoventrite very narrow at anterior margin, bearing a transverse ridge posteromedially; elytra of variable coloration, but never pale with dark stripes along elytral series; elytra in some species with elevated or costate alternate intervals.

Larva: Head prognathous; nasale simply triangular or with lobate lateral margins; epistomal lobes large, slightly overlapping nasale, bearing series of stout setae; mandible with two retinacular teeth; labium without ligula; each parietale with 6 stemmata situated in area of darker cuticle; all thoracic segments with large dorsal tergite; abdominal segments 1–8 each with a pair of dorsal sclerites and an additional large sclerite laterally of them on each side; tracheal system holopneustic, spiracular atrium absent; urogomphi large, three-segmented.