''Aphaenogaster praerelicta'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

in the subfamily

Myrmicinae Myrmicinae is a subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily ...

known from a solitary

Late Oligocene The Chattian is, in the geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the pro ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

fossil found in

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. At the time of description ''A. praerelicta'' was one of three ''Aphaenogaster'' species known from Mexico.

History and classification

''Aphaenogaster praerelicta'' is known from a solitary fossil insect which is an

inclusion Inclusion or Include may refer to: Sociology * Social inclusion, action taken to support people of different backgrounds sharing life together. ** Inclusion (disability rights), promotion of people with disabilities sharing various aspects of lif ...

in a transparent chunk of

Mexican amber Mexican amber, also known as Chiapas Amber is amber found in Mexico, created during the Early Miocene and middle Miocene epochs of the Cenozoic Era in southwestern North America. As with other ambers, a wide variety of taxa have been found as in ...

along with three

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

, two

springtail Springtails (class Collembola) form the largest of the three lineages of modern Hexapoda, hexapods that are no longer considered insects. Although the three lineages are sometimes grouped together in a class called Entognatha because they have in ...

s, a

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

, and some pollen grains. Mexican amber is recovered from fossil bearing rocks in the

Simojovel Simojovel is a Municipalities of Chiapas, municipality in the List of states in Mexico, Mexican state of Chiapas in southern Mexico. As of 2010, the municipality had a total population of 40,297, up from 31,615 as of 2005. It covers an area of ...

region of

Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...

, Mexico. The amber dates from between 22.5 million years old, representing the youngest sediments of the Balumtun Sandstone, and the 26 million year old La Quinta Formation. This age range straddles the boundary between the

and

and is complicated by both formations being secondary deposits for the amber: the age range represents only the youngest that it might be. The amber was produced by either of two extinct ''

Hymenaea ''Hymenaea'' is a genus of plants in the legume family Fabaceae. Of the fourteen living species in the genus, all but one are native to the tropics of the Americas, with one additional species ('' Hymenaea verrucosa'') on the east coast of ...

'' species, ''

Hymenaea mexicana ''Hymenaea mexicana'' is an extinct legume species in the family Fabaceae described from a series of isolated fossil petals, leaflets, and amber. The species is known from a group of Late Oligocene to Early Miocene locations in southern Mexico. ...

'' or ''

Hymenaea allendis ''Hymenaea allendis'' is an extinct legume species in the family Fabaceae described from a single isolated fossil flower in amber. The species is known from a Late Oligocene to Early Miocene location in southern Mexico. Unlike the coeval extinc ...

'', both of which were initially described from fossil flowers included in Mexican amber. The fossil is part of the amber collection of George Poinar Jr., which at the time of description, was housed at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

. The fossil ant was first studied by paleoentomologist Maria De Andrade of the

University of Basel The University of Basel (Latin: ''Universitas Basiliensis''; German: ''Universität Basel'') is a public research university in Basel, Switzerland. Founded on 4 April 1460, it is Switzerland's oldest university and among the world's oldest univ ...

. De Andrade's 1995

type description A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

of the new species was published in the German journal ''Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie)''. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''praerelicta'' is a combination of the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

"prae" meaning ''before'' and "relicta", the species name for the modern '' Aphaenogaster relicta'' of

Haiti Haiti, officially the Republic of Haiti, is a country on the island of Hispaniola in the Caribbean Sea, east of Cuba and Jamaica, and south of the Bahamas. It occupies the western three-eighths of the island, which it shares with the Dominican ...

, to which ''A. praerelicta'' is most similar. ''A. praerelicta'' is one of two species described by De Andrade in the 1995 paper: the other species '' Aphaenogaster amphioceanica'' was found in

Dominican amber Dominican amber is amber from the Dominican Republic derived from resin of the extinct tree '' Hymenaea protera''. Dominican amber differentiates itself from Baltic amber by being nearly always transparent, and it has a higher number of fossil in ...

. Three l species of ''Aphaenogaster'' are currently known from Mexico, the fossil ''A. praerelicta'', '' A. ensifera'' and '' A. mexicana''.

Description

The ''Aphaenogaster praerelicta'' specimen is a well-preserved worker caste adult with an estimated body length of approximately . The overall coloration of ''A. praerelicta'' is a brown tone, with the legs and posterior borders of the

tergites A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'margin'. ...

shading slightly lighter. The body has numerous long thick hairs which range from fully erect to lying down against the exoskeleton. The head widens towards the posterior edge and lacks the "neck" which is seen in ''A. amphioceanica''. While the hollows where the antennae were attached to the head capsule are small, the antennae of ''A. praerelicta'' are unknown, as they were lost before the specimen was entombed. The head capsule has numerous deep anatomizing ridges over which a strong reticulation is superimposed. The propodeum is notable in having two spines long that point upwards and backwards and another set of spines at the humeral angle closer to the head. The combination of no "neck", short humeral spines and long posterior spines on the propodeum are unique. The character combination is similar to that of several modern North American species and ''A. relicta'' of Hati.

References

{{Taxonbar, from=Q15733597 praerelicta Miocene insects of North America Fossil ant taxa Fossil taxa described in 1995 Mexican amber Species known from a single specimen