''Arrenurus'' (αρρεν - male, ουρά - tail) is a genus of water mites within the family Arrenuridae, and was first described by Antoine Louis Dugès in 1834. It has a cosmopolitan distribution in

lentic A lake ecosystem or lacustrine ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example of lentic ecosystems (''lentic'' ref ...

waters, even on remote Pacific islands, and is found on every continent, with the possible exception of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. Some 950 species are currently recognised, making ''Arrenurus'' the largest of genera. ''Arrenurus'' goes through seven stages - egg, inactive prelarva, larva, protonymph,

deutonymph Mites start as an egg and then may pass through up to six instars: prelarva, larva, protonymph, deutonymph, tritonymph, and adult. These developmental stages may look different or may be omitted depending on the mite group. All mites have an adult ...

, tritonymph, and adult, only the larval stage being parasitic, and marked sexual dimorphism in the heavily sclerotised adults. Taxonomy of females is often problematic, but relatively simple in the males. ''Arrenurus'' larvae are ectoparasites of some aquatic insects in freshwater habitats, particularly the

Odonata Odonata is an order of predatory flying insects that includes the dragonflies and damselflies (as well as the '' Epiophlebia'' damsel-dragonflies). The two major groups are distinguished with dragonflies (Anisoptera) usually being bulkier with ...

(Dragonflies and Damselflies). These mites establish an association for the purpose of transportation and nutrients, and attach to the host during the host's transition from larva to adult. Andrew et al. 2012, found that it is mainly ''Arrenurus'' species that are to be found on Odonata. Studies also show that parasitism by the mites affect the host's longevity and fecundity by draining its tissue fluids, hampering copulation and interfering with sperm transfer. ''Arrenurus'' larvae are also ectoparasites of

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

and

Coleoptera Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

. After the odonate has left the water and shed its skin, mites move from the

exuviae In biology, exuviae are the remains of an exoskeleton and related structures that are left after ecdysozoans (including insects, crustaceans and arachnids) have molted. The exuviae of an animal can be important to biologists as they can often be ...

onto the still soft adult. They often select the ventral parts of the thorax or abdomen, and to a lesser extent are found on the back or on the head, or on the major wing veins. After penetrating the dermis of the host, the larval mite produces a

stylostome The stylostome is a funnel- or channel-like structure formed in response to Trombiculidae, trombiculid mites. The formation is not caused by the mouthparts of the mites, because these mites do not have needle-like mouthparts as hematophagia, hema ...

, or small blind sac, within the host's body. Most stylostomes are able to resist assault by the host's immune system, such action consisting of initial hemolymph clotting, and deposition of

melanin Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...

around the sac and its encapsulation. Feeding from the host is only one of the aims - the other is

phoresy Phoresis or phoresy is a temporary commensalistic relationship when an organism (a phoront or phoretic) attaches itself to a host organism solely for travel. It has been seen in ticks and mites since the 18th century, and in fossils 320 ...

or using the host for transportation. Many mites are phoretic - the benefits being dispersal, fresh habitat, and expanding the

gene pool The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species. Description A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survi ...

References

External links

''Recherches sur l'ordre des Acariens en général et la famille des Trombidiés en particular''
* ''Dragonflies: Behavior and Ecology of Odonata'' - Philip Corbet (1999) {{Taxonbar, from=Q4625192 Arrenuridae Trombidiformes genera