''Unionicola'' is a genus of freshwater

arachnids Arachnids are arthropods in the class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroons. Adult arachnids ...

, specifically water mites, belonging to the family Unionicolidae. The genus was described in 1842 by

Samuel Stehman Haldeman Samuel Stehman Haldeman (August 12, 1812 – September 10, 1880) was an American natural history, naturalist and philologist. During a long and varied career he studied, published, and lectured on geology, conchology, entomology and philology. He ...

. The genus has

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

. Most ''Unionicola'' are associated with

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

, but ''Unionicola crassipes'' and ''Unionicola minor'' are associated with

sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar ...

of family

Spongillidae Spongilidae is a family of sponges that live in freshwater lakes and rivers. The following genera are recognized in the family: * '' Anheteromeyenia'' Schröder, 1927 * '' Corvoheteromeyenia'' Ezcurra de Drago, 1979 * '' Corvospongilla'' Annanda ...

. The association with

mussels Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, whic ...

can be described as symbiotic. There is evidence that mites consume host tissue and can be associated with reduced host fitness, although the causal direction of the latter remains unclear. Species include the following: * ''Unionicola gracilipalpis'' * ''Unionicola figuralis'' * ''Unionicola crassipes'' * ''Unionicola aculeata'' * ''Unionicola ypsilophora'' (Bonz, 1783)

References

{{Taxonbar, from=Q4645080 Trombidiformes Acari genera Taxa named by Samuel Stehman Haldeman Cosmopolitan arachnids