Aneuretellus
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''Aneuretellus'' is an
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
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
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...
in the formicid subfamily
Aneuretinae Aneuretinae is a subfamily of ants consisting of a single extant species, ''Aneuretus simoni'' ( Sri Lankan relict ant), and 9 fossil species. Earlier, the phylogenetic position of ''A. simoni'' was thought to be intermediate between primitive a ...
, and is one of eight genera of the subfamily. The genus contains a single described species ''Aneuretellus deformis'' and is known from one
Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...
fossil which was found in
Sakhalin Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh: ...
in the
Russian Far East The Russian Far East (russian: Дальний Восток России, r=Dal'niy Vostok Rossii, p=ˈdalʲnʲɪj vɐˈstok rɐˈsʲiɪ) is a region in Northeast Asia. It is the easternmost part of Russia and the Asian continent; and is admini ...
.


History and classification

When first described, ''A. deformis'' was known from a single fossil insect included in a transparent chunk of Sakhalin amber. When the fossil was described it was part of the amber collections housed in the Paleontological Institute of the
Russian Academy of Sciences The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across t ...
. The amber was recovered from fossil bearing rocks in the Sakhalin region of Eastern Russia. Sakhalin amber is noted for having undergone high temperatures and pressures after the resin was buried. As a result insects and other inclusions in the amber are not as well preserved as those of other amber locations, even those of older ambers. The inclusions are most of the time carbonized reducing fine detail preservation, and the amber has been subjected to
plastic deformation In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain ...
changing the shapes and features of the inclusions. The distortion is visible in the outlines of trapped air bubbles, which are elongated along the plane of distortion, rather than spherical as seen with bubbles in Eocene
Baltic amber The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite. It was produced sometime during the Eocene epoch, but exactly when is controversial. It has been estimated that these forests created more than 1 ...
and Cretaceous
Taymyr amber Taymyr or Taimyr may refer to: Places *Taymyr Peninsula, a peninsula in Siberia *Taymyr Gulf *Taymyra, a river in the Taymyr Peninsula *Lake Taymyr *Taymyr Island, an island in the Kara Sea *Taymyr Autonomous Okrug, a former federal subject of Rus ...
. In some cases the inclusions are at least partially filled with amber rather than being hollow. Sakhalin amber has been attributed a range of geological ages, with
Vladimir Zherikhin Vladimir Vasilevich Zherikhin (russian: Владимир Васильевич Жерихин, 22 July 194521 December 2001), of the Paleontological Institute, Russian Academy of Sciences, Moscow, was one of the world's leading paleoentomologists ...
in 1978 suggesting dates between 59 and 47 million years old. In 1988,
Gennady Dlussky Gennady ( rus, Геннадий, p=ɡʲɪˈnadʲɪj), also spelled Gennadi or Gennadiy, is a Russian male name. They are derived from the Greek given name Gennadius. People *Gennady Gladkov, Soviet and Russian composer *Gennady Golovkin, Kazakh bo ...
suggested a tentative Paleocene age, which was followed by subsequent authors through 2013. However research published in 1999 on the Naibuchi Formation, in which Sakhalin amber is directly preserved, gives a Middle Eocene age based on geological and paleobotanical context. The Sakhalin amber forest had a variety of plants living in a mixed coastal swamp, river, and lake environment. The river and lake system had numerous swampy areas that resulted in active
peat bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
formation. The bogs were surrounded by ''
Osmunda ''Osmunda'' is a genus of primarily temperate-zone ferns of family Osmundaceae. Five to ten species have been listed for this genus. Description Completely dimorphic fronds or pinnae (hemidimorphic), green photosynthetic sterile fronds, and no ...
'',
Nymphaeaceae Nymphaeaceae () is a family of flowering plants, commonly called water lilies. They live as rhizomatous aquatic herbs in temperate and tropical climates around the world. The family contains nine genera with about 70 known species. Water li ...
and
Ericaceae The Ericaceae are a family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with c.4250 known species spread across 124 genera, making it th ...
plants, while ''
Taxodium ''Taxodium'' is a genus of one to three species (depending on taxonomic opinion) of extremely flood-tolerant conifers in the cypress family, Cupressaceae. The generic name is derived from the Latin word ''taxus'', meaning " yew", and the Greek ...
'', ''
Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'', ''
Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...
'', and other trees populated the forest. The amber fossil was first studied by paleoentomologist Gennady Dlussky of the Russian Academy of Sciences, with his 1988
type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...
for the species published in ''Paleontologicheskii Zhurnal''. The species name ''deformis'' was coined from the Latin word meaning "deformed". The etymology of the genus name ''Aneuretellus'' was not explained by Dlussky. Based on the structure of the petiole and shape of the gaster, Dlussky placed ''A. deformis'' into the ant subfamily Aneuretinae. The subfamily includes three additional extinct genera, '' Mianeuretus'', ''
Paraneuretus ''Paraneuretus'' is an extinct genus of formicid in the ant subfamily Aneuretinae known from fossils found in Asia and Europe. The genus contains three middle to late Eocene age species, ''Paraneuretus dubovikoffi'', ''Paraneuretus longicornis ...
'', and '' Protaneuretus'', and a single living genus and species '' Aneuretus simoni'', found in Sri Lanka.


Description

The lone worker of ''Aneuretellus'' has a body length of , a head length of and antennae with twelve segments. The head is generally
trapezoid A quadrilateral with at least one pair of parallel sides is called a trapezoid () in American and Canadian English. In British and other forms of English, it is called a trapezium (). A trapezoid is necessarily a Convex polygon, convex quadri ...
in shape, with a notably convex rear margin. The antennae have a basal segment, that does not reach past the occipital margin, eleven additional segments, the last three of which are enlarged and form a terminal club. The eyes are shifted forward on the head, while the funicular segments, those between the scape and club, are thickened. Both are features seen in ant species that typically soil or leaf litter dwelling. Due to positioning of the worker in the amber, two of the important features distinguishing the subfamily Aneuretinae genera are not directly visible. An elongated one segmented petiole is indicated by the lower impression of the petiole in the amber, though the upper portion of the petiole along with the upper portion of the mesosoma after the
pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on ea ...
are missing from the specimen. Though the junction of the petiole with the gaster is missing, the lower impression of the petiole shows it was probably widening at the junction.


References

{{Taxonbar, from=Q18102276 †Aneuretellus Fossil taxa described in 1988 Insects of Asia Eocene insects Fossil ant genera Sakhalin amber