''Dytiscacarus'' is a genus of trombidiform

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s that are sub-elytral parasites of diving beetles (

Dytiscidae The Dytiscidae, from the Ancient Greek word δυτικός (''dystikos''), meaning "able to dive", are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species l ...

). It is in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Dytiscacaridae, and comprises three species. It has been recorded from

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

and the United States.

Morphology

The family has three distinctive features not found in other mites (

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...

): the infracapitulum has a pair of gnathosomatic neostigmata on its dorsal face, the movable cheliceral stylets are sheathed and can be deeply retracted into the

prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

, and the pretarsi of all legs lack empodia and bear paired claws strongly modified into sclerotized tenent-like structures (to attach to hosts). These features occur in all of the active life stages. Dytiscacaridae are also

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

: females have the fourth pair of legs elongated (possibly for greater mobility), while males have a caudal copulatory capsule.

Biology

Dytiscacaridae spend their life cycle under the

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

of Dytiscidae beetles. The eggs are laid on the inner surface of the elytra, being glued there by a gelatinous substance. It is possible, though not yet confirmed, that these mites pierce the beetle's wings with their stylets to feed on

hemolymph Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph c ...

. It is unknown how the mites disperse from beetle to beetle. It may be that like other heterostigmatan mites, adult females are the dispersants. They may be

sexually transmitted A sexually transmitted infection (STI), also referred to as a sexually transmitted disease (STD) and the older term venereal disease (VD), is an infection that is spread by sexual activity, especially vaginal intercourse, anal sex, oral ...

, dispersing from beetle to beetle during mating.

Species

* '' Dytiscacarus americanus'' Mortazavi and Hajiqanbar, 2018 – US. Host ''

Hydaticus bimarginatus ''Hydaticus'' is a genus of predatory water beetle belonging to the family Dytiscidae. ''Hydaticus'' can be found throughout most of the world. There are 150 described species and 12 subspecies in two subgenera in the genus ''Hydaticus''. Subg ...

'' * '' Dytiscacarus iranicus'' Mortazavi and Hajiqanbar, 2018 – Iran. Host '' Hydaticus pictus'' * '' Dytiscacarus thermonecti'' Mortazavi and Hajiqanbar, 2018 – US. Host '' Thermonectus basillaris''

References

{{Taxonbar, from1=Q113163339 Raphignathoidea Parasitic acari Parasites of insects