Opilioacaridae is the sole family of

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 in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Opilioacarida, made up of about 13 genera. The mites of this family are rare, large (1.5 to 2.5 mm) mites, and are widely considered primitive, as they retain six pairs of

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s, and abdominal segmentation. They have historically been considered separate from other mites belonging to

Acariformes The Acariformes, also known as the Actinotrichida, are the more diverse of the two superorders of mites. Over 32,000 described species are found in 351 families, with an estimated total of 440,000 to 929,000 species, including undescribed speci ...

and

Parasitiformes Parasitiformes are a superorder of Arachnids, constituting one of the two major groups of mites, alongside Acariformes. Parasitiformes has, at times, been classified at the rank of order or suborder. It is uncertain whether Parasitiformes and Ac ...

, but are now generally considered a subgroup of Parasitiformes based on

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

. The first member of the Opilioacarida to be discovered was the

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

n species '' Opilioacarus segmentatus'', which was described by

Carl Johannes With Carl Johannes With (11 December 1877 – 16 June 1923) was a Danish medical doctor and arachnologist, specialising in pseudoscorpions and mites. With was born in Lemvig to Nicolai Rasmus With and his wife Rasmine Sophie Dorothea With, but was or ...

in 1902, followed by the Sicilian '' Eucarus italicus'' and '' Eucarus arabicus'' from

Aden Aden () is a port city located in Yemen in the southern part of the Arabian peninsula, on the north coast of the Gulf of Aden, positioned near the eastern approach to the Red Sea. It is situated approximately 170 km (110 mi) east of ...

, both in 1904. Two

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

specimens are known, one of which was discovered in

Baltic amber Baltic amber or succinite is amber from the Baltic region, home of its largest known deposits. It was produced sometime during the Eocene epoch, but exactly when is controversial. It has been estimated that this forested region provided the re ...

from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

, while the other one was discovered in the

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

(

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

) around 99 million years old, tentatively assigned to the living genus '' Opilioacarus.'' Members of the group live in semi-arid and tropical environments in

leaf-litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituent ...

, under rocks and in caves. Their diet is known to include arthropod carcasses, fungal spores, and pollen.

Genera

These 13 genera belong to the family Opilioacaridae: * '' Adenacarus'' Hammen, 1966 * '' Amazonacarus'' Vázquez, Araújo & Feres, 2014 * '' Brasilacarus'' Vázquez, Araújo & Feres, 2015 * '' Caribeacarus'' Vázquez & Klompen, 2009 * '' Indiacarus'' Das & Bastawade, 2007 * '' Neocarus'' Chamberlin & Mulaik, 1942 * '' Opilioacarus'' With, 1902 * '' Panchaetes'' Naudo, 1963 * '' Paracarus'' Chamberlin & Mulaik, 1942 * '' Phalangiacarus'' Coineau & Hammen, 1979 * '' Salfacarus'' Hammen, 1977 * '' Siamacarus'' Leclerc, 1989 * '' Vanderhammenacarus'' Leclerc, 1989

References

External links

* {{Taxonbar, from1=Q136926, from2=Q14849555 Acari taxonomy Arachnid orders Monotypic arthropod taxa