- Source: Georissus
Georissus, also called minute mud-loving beetles, is the only genus in the beetle family Georissidae (or Georyssidae). They are tiny insects living in wet soil, often near water. They are found on every continent except Antarctica.
Characteristics
Georissidae are small beetles (length 1–2 mm). They have a broadly oval body whose outline is more or less interrupted between the pronotum and the elytra. The head and pronotum are granulate, the prosternum is rudimentary, without intercoxal processes. The anterior coxae and trochanters are fused. The basal ventrite is very large.
Ecology
Species are generally found within mud and sand at the periphery of rivers and streams, but also occur in tropical rainforest leaf litter. Species of Georissus are predators on invertebrates, and under laboratory conditions sometimes engage in cannibalism. Species within the genus are known for their habit of psammophory (actively covering their elytra with sand or mud) which helps protect them against predators.
Systematics and evolution
There are about 75 living species, including:
Georissus australis
Georissus babai
Georissus bipartitus
Georissus caelatus
Georissus californicus
Georissus canalifer
Georissus capitatus
Georissus coelosternus
Georissus costatus
Georissus crenulatus
Georissus formosanus
Georissus fusicornis
Georissus granulosus
Georissus instabilis
Georissus japonicus
Georissus kingii
Georissus kurosawai
Georissus laesicollis
Georissus minusculus
Georissus occidentalis
Georissus pusillus
Georissus sakaii
Georissus septemcostatus
Georissus substriatus
Georissus trifossulatus
The genus is divided into three subgenera (Georissus, Neogeorissus and Nipponogeorissus). Formerly it was included within the family Hydrophilidae. Recent molecular data indicate, that they belong to a clade comprising the small groups of Hydrophiloidea - Epimetopidae, Hydrochidae, Helophoridae and Georissidae.