| Hygrobia | |
|---|---|
 | |
| Hygrobia hermanni | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Adephaga |
| Family: | Hygrobiidae |
| Genus: | Hygrobia Latreille, 1804 |
| Species | |
| |
Hygrobia is agenus of aquaticbeetles native toEurope,North Africa,China andAustralia. It is the only genus in thefamilyHygrobiidae, also known as thePaelobiidae.[1] These are known commonly assqueak beetles[2] orscreech-beetles.[3]
There are six known livingspecies, with a highly disjunct distribution, and one extinct species,Hygrobia cretzschmari.
All species occur in lowland areas[4] and are mainly found in stagnant water.[5] They live in the mud, silt, and detritus of ponds.[4]
None of the species occur insympatry, except forH. nigra andH. australasiae in south-eastern Australia.[6]
Both adults and larvae arepredators, specialized onoligochaete worms. The adults feed for as long as 30 min, coming to the surface very briefly to renew the air-supply.[7]
Adults are able tostridulate, producing an audible sound,[8] which is why they are called squeak or screech beetles.
The body length ranges from 8.0 to 11.0 mm.Compound eyes are present, not divided into ventral and dorsal portions, strongly protruding.Labrum is short and transverse. Theantennae are filiform, almost glabrous, with 11 segments.[5]
Themonophyly of the family is not in doubt.[6]
Hygrobiidae is thought to be thesister group to a clade comprisingDytiscidae (diving beetles),Amphizoidae (trout stream beetles) andAspidytidae (cliff beetles), based onDNA sequence data.[6][9][10]
Regarding the relationships among the species ofHygrobia, a recent phylogenetic analysis suggested a sister group relationship betweenH. hermanni and a clade formed by the Australian species, withH. nigra sister toH. australasiae.[6]
Hygrobiidae probably diverged from other Hydradephagan clades around the time of the initial breakup ofPangea. The split between today'sPalearctic and Australian clades occurred later, possibly in the middleMesozoic, by dispersal events.[6]
Hygrobia australasiae (Clark, 1862) - Australia
Hygrobia davidi Bedel, 1883 -Jiangxi, southeastern China
Hygrobia hermanni (Fabricius, 1775) - Europe, northern Africa (Morocco,Algeria andTunisia), andIsrael
Hygrobia maculata Britton, 1981 - Australia
Hygrobia nigra (Clark, 1862) - Australia
Hygrobia wattsi Hendrich, 2001 - Australia
There has been a controversy associated with deciding which is the valid family name of squeak beetles: Hygrobiidae or Paelobiidae.[1] Paelobiidae has priority over Hygrobiidae, but the latter name was until recently much more widely used.[11]
