''Pachycondyla oligocenica'' 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 ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of formicid in the ant subfamily Ponerinae known from a fossil found in eastern Asia.

History and classification

''P. oligocenica'' is known from a single ant found in Russia. The specimen was described from a compression fossil preserved in diatomite deposits of the Bol’shaya Svetlovodnaya site. The site is exposed on the bank of Barachek Creek upstream from the creeks confluence with the Bol’shaya Svetlovodnaya River in the

Pozharsky District Pozharsky District (russian: Пожа́рский райо́н) is an administrativeLaw #161-KZ and municipalLaw #191-KZ district (raion), one of the twenty-two in Primorsky Krai, Russia. It is located in the northern and northwestern parts of t ...

, on the Pacific Coast of Russia. The fossil-bearing rocks preserve possibly

Priabonian The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage of t ...

plants and animals which lived in and around a small lake near a volcano. The site has been attributed to either the Maksimovka or Salibez Formations and compared to the Bembridge Marls and Florissant Formation, both of which are Priabonian in age. At the time of description, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

male specimen, number PIN 3429/1112 was preserved in the A. A. Borissiak Paleontological Institute collections, part 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 fossil was first described by the trio of paleomyrmecologists Gennady Dlussky,

Alexandr Rasnitsyn Alexandr Pavlovich Rasnitsyn (Russian: Александр Павлович Расницын) is a Russian entomologist, expert in palaeoentomology, and Honored Scientist of the Russian Federation (2001). His scientific interests are centered on ...

and Ksenia Perfilieva. In the type description, Dlussky, Rasnitsyn and Perfilieva named the species ''P. oligocenica'', with the

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

derived "Oligocene" the possible age of the site. At the time of description, only two other ''Pachycondyla'' species males had been described from fossils; the males of both '' P. baltica'' and '' P. succinea'' are known from fossils entombed in Eocene age

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 ...

. ''P. oligocenica'' is distinguished from both baltic amber species in that the holotype male is larger than the other males, males of those species with bodies ranging between long. ''P. oligocenica'' is one of two ''Pachycondyla'' species that were described by Dlussky, Rasnitsyn and Perfilieva from Bol’shaya Svetlovodnaya, the other species '' P. aberrans'' being described from a partial queen or male. Pachycondyla succinea BMNHP29202 full 01

Pachycondyla succinea BMNHP29202 full 01

Description

Though incomplete, the ''P. oligocenica'' male has an estimated body length of , while the alitrunk is . The head has an almost square outline, being slightly shorter than it is wide, and the rear edge is rounded. The large oval shaped eyes convex in shape, protruding slightly from the head capsule. Neither of the mandibles have any teeth along the edges, and they are placed far apart on the head, preventing touching when they close. The antennae are not preserved from the holotype, so the structure and length was unknown at the time of description. The forewing has a length of with the veins fully enclosing and forming the cells 1+2r, 3r, mcu, and rm. The rm cell is not present in the forewing of ''P. aberrans'', distinguishing the two species.

References

{{Taxonbar, from=Q27666792 Eocene insects Fossil ant taxa Fossil taxa described in 2015 Cenozoic insects of Asia †Pachycondyla oligocenica Insects described in 2015