Introduction

This small family contains the single genus Sphaerites Duftschmid, 1805 with four, or possibly five, species and is widespread in northern temperate regions. One species, S. politus Mannerheim, 1864 occurs in the northern United States, Canada and Alaska; it is found in carrion, compost and bear dung (Ursus spp.). Two species are widespread across southern Asia, S. dimidiatus Juracek, 1934 and S. nitidus Löbl, 1996. The widespread Palaearctic and Siberian species, S. glabratus (Fabricius, 1792), is the only one to occur in the U.K. These are small to medium sized beetles, 5.5-6.5mm, superficially similar to some broad-bodied Histerids but much less compact with a body length to width ratio of 1.6-1.7. The upper surface is glabrous and shiny, darkly coloured, often black, and with a metallic blue or green lustre. The antennae are relatively short and only weakly geniculate; 11-segmented with a cupule and a pubescent 3-segmented club, the insertions visible from above.  Head narrow compared to the pronotal width, with strongly protruding and finely-faceted eyes. Each elytron has 9 regular rows of punctures and lacks a scutellary striole. Smoothly rounded and truncate; exposing the pygidium but not the propygidium. The scutellum is always large and triangular. All species are fully winged and fly. Abdomen with 5 exposed sternites which are all articulated. The legs are not retractable to the extent of Histerids and the front tarsi do not retract into tibial grooves. Tarsi 5-5-5. Claws smooth. All species are terrestrial and associated with decaying organic matter, the adults are seldom recorded.