''Hygrobia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of aquatic

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s native to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is the only genus in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Hygrobiidae, also known as the Paelobiidae.Nilsson, A. N. (2006)
Which name is valid – Hygrobiidae or Paelobiidae?
''Latissimus'' 21 37–39. These are known commonly as squeak beetles or screech-beetles. There are six known living

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, with a highly disjunct distribution, and one extinct species, ''Hygrobia cretzschmari''.

Biology

All species occur in lowland areas Dettner, K. (2005). Noteridae. ''Handbook of Zoology'', ''4'', 72–90. and are mainly found in stagnant water.Holmen, M. (1987). Family Hygrobiidae. ''The aquatic Adephaga (Coleoptera) of Fennoscandia and Denmark''. Brill, 136–142. They live in the mud, silt, and detritus of ponds. None of the species occur in

sympatry In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...

, except for ''H. nigra'' and ''H. australasiae'' in south-eastern Australia.Hawlitschek, O., Hendrich, L., & Balke, M. (2012). Molecular phylogeny of the squeak beetles, a family with disjunct Palearctic-Australian range. ''Molecular Phylogenetics and Evolution'', ''62''(1), 550–554. Both adults and larvae are

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s, specialized on

oligochaete Oligochaeta () is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworms ...

worms. The adults feed for as long as 30 min, coming to the surface very briefly to renew the air-supply. Adults are able to

stridulate Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...

, producing an audible sound, which is why they are called squeak or screech beetles.

Morphology

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. The antennae are filiform, almost glabrous, with 11 segments.

Phylogeny and evolution

The

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

of the family is not in doubt. Hygrobiidae is thought to be the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to a clade comprising Dytiscidae (diving beetles), Amphizoidae (trout stream beetles) and Aspidytidae (cliff beetles), based on DNA sequence data. Regarding the relationships among the species of ''Hygrobia'', a recent phylogenetic analysis suggested a sister group relationship between ''H. hermanni'' and a clade formed by the Australian species, with ''H. nigra'' sister to ''H. australasiae.'' Hygrobiidae probably diverged from other Hydradephagan clades around the time of the initial breakup of

Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

. The split between today's

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

and Australian clades occurred later, possibly in the middle

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

, by dispersal events.

Species diversity and distribution

''Hygrobia australasiae'' (Clark, 1862) - Australia ''Hygrobia davidi'' Bedel, 1883 -

Jiangxi Jiangxi (; ; formerly romanized as Kiangsi or Chianghsi) is a landlocked province in the east of the People's Republic of China. Its major cities include Nanchang and Jiujiang. Spanning from the banks of the Yangtze river in the north int ...

, southeastern China ''Hygrobia hermanni'' (Fabricius, 1775) - Europe, northern Africa (

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...

and

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

), and

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

''Hygrobia maculata'' Britton, 1981 - Australia ''Hygrobia nigra'' (Clark, 1862) - Australia ''Hygrobia wattsi'' Hendrich, 2001 - Australia

Family name

There has been a controversy associated with deciding which is the valid family name of squeak beetles: Hygrobiidae or Paelobiidae. Paelobiidae has priority over Hygrobiidae, but the latter name was until recently much more widely used.Lawrence, J. F., & Newton, A. F. (1995). Families and subfamilies of Coleoptera with selected genera, notes, references and data on family-group names. p. 779-1006 n:Biology, Phylogeny and Classification of Coleoptera. Papers celebrating the 80th birthday of Prof. Roy A. ''Museum i Instyut Zoologii PAN, Warzawa''.

References

External links

''Hygrobia''.
Fauna Europaea. {{Taxonbar, from=Q15635851 Adephaga genera Palearctic insects Insects of Australia