Pachysternum

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Subclassis: Pterygota
Cladus: Metapterygota
Infraclassis: Neoptera
Cladus: Eumetabola
Cladus: Endopterygota
Superordo: Coleopterida
Ordo: Coleoptera
Subordo: Polyphaga
Infraordo: Staphyliniformia
Superfamilia: Hydrophiloidea

Familia: Hydrophilidae
Subfamilia: Sphaeridiinae
Tribus: Megasternini
Genus: Pachysternum
References

Fikáček, M.; Boukal, M. 2004: Pachysternum capense, a new genus and species for Europe, and updated key to genera and subgenera of European Sphaeridiinae (Coleoptera: Hydrophilidae). Klapalekiana, 40: 1–12. Full article (PDF) Reference page.
Fikáček, M.; Jia, F.; Prokin, A. 2012: A review of the Asian species of the genus Pachysternum (Coleoptera: Hydrophilidae: Sphaeridiinae). Zootaxa 3219: 1–53. Preview Reference page.
Lõkkös, A.; Boukal, M.; Fikáček, M. 2014: The hydrophilid beetle Pachysternum capense (Mulsant, 1844) (Coleoptera: Hydrophilidae) became a world-wide adventive species: a summary of distribution with new records from Europe, Australia, and South America. North-western journal of zoology 10(2): 333–336. Full article (PDF) Reference page.