The Trachypachidae are a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s that generally resemble small ground beetle

Ground beetle

Ground beetles are a large, cosmopolitan family of beetles, Carabidae, with more than 40,000 species worldwide, approximately 2,000 of which are found in North America and 2,700 in Europe.-Description and ecology:...

s, but that are distinguished by the large coxa

Coxa

Coxa may refer to:* Theta Leonis, a star* Nickname of Brazilian soccer team Coritiba Foot Ball Club* Hip, below the lateral side of the abdomen* The short most-proximal base jointed segment of the arthropod leg...

e of their rearmost legs. Only six species are known in the family, with four species of Trachypachus found in northern Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 and northern North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, and two species of Systolosoma in Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

.

Their habits are similar to those of the ground beetles; they are usually found in the leaf litter of conifer forests.

To quote G. E. Ball, "the most interesting thing about this small family is its uncertain phylogenetic relationships"; it has been classified as a subfamily of Carabidae, and as a family been placed in several different positions relative to other beetle families.

Species

• Genus Systolosoma
  • Systolosoma breve
  • Systolosoma lateritium

• Genus Trachypachus
  • Trachypachus holmbergi
  • Trachypachus gibbsii
  • Trachypachus zetterstedi
  • Trachypachus slevini