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. Found on every continent except Antarctica.

Georissus
G. crenulatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Superfamily: Hydrophiloidea
Family: Georissidae
Laporte, 1819
Genus: Georissus
Latreille, 1809
Species

see text

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.[1]

Species within this genus are known for their habit of psammophory (actively covering their elytra with sand or mud) which helps protect them against predators).[2]

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.[3]

References
  1. M.Hansen. Phylogeny and classification of the staphyliniform beetle families (Coleoptera). Biologiske Skrifter 48, Copenhagen, 1997
  2. Bameul, Franck (1989-01-01). "Description of the camouflage behaviour of a Coleoptera: The active disguise of Georissus crenulatus (Coleoptera Georissidae), and proposal of a new classification of disguises among invertebrates". 309: 351–356. Cite journal requires |journal= (help)
  3. D.Bernhard et al., From terrestrial to aquatic habitats and back again — molecular insights into the evolution and phylogeny of Hydrophiloidea (Coleoptera) using multigene analyses. Zoologica Scripta 35 (6) , 597–606, 2006


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