''Aphaenogaster sommerfeldti'' is an extinct

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 ...

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 ...

in the subfamily Myrmicinae known from a group of

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'', "da ...

fossils found in Europe. ''A. sommerfeldti'' is one of three species in the ant genus '' Aphaenogaster'' to have been noted from fossils found in

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 ...

William Morton Wheeler William Morton Wheeler (March 19, 1865 – April 19, 1937) was an American entomologist, myrmecologist and Harvard professor. Biography Early life and education William Morton Wheeler was born on March 19, 1865, to parents Julius Morton Wheel ...

History and classification

When first examined, ''Aphaenogaster sommerfeldti'' was described from a pair of

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

workers which are fossilized as inclusions in transparent chunks of

. Baltic amber is approximately forty six million years old, having been deposited during

Lutetian The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the ...

stage of the

. There is debate on what plant family the amber was produced by, with evidence supporting relatives of either an '' Agathis'' relative or a ''

Pseudolarix ''Pseudolarix'' is a genus of coniferous trees in the pine family Pinaceae containing three species, the extant '' Pseudolarix amabilis'' and the extinct species '' Pseudolarix japonica'' and '' Pseudolarix wehrii''. ''Pseudolarix'' species are ...

'' relative. All the type specimens were collected over 125 years ago, and when first described were part of the

University of Königsberg The University of Königsberg (german: Albertus-Universität Königsberg) was the university of Königsberg in East Prussia. It was founded in 1544 as the world's second Protestant academy (after the University of Marburg) by Duke Albert of Pruss ...

amber collection. The fossils were first studied by Austrian entomologist

Gustav Mayr Gustav L. Mayr (12 October 1830 – 14 July 1908) was an Austrian entomologist and professor in Budapest and Vienna. He specialised in Hymenoptera, being particularly known for his studies of ants.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 ...

of the new species was published in the Königsberg journal '' Beiträge zur Naturkunde Preussens''.

in his 1915 paper ''The ants of the Baltic amber'' noted that the University of Königsberg collections then contained a total of fourteen workers, plus one unnumbered specimen. An additional three were present in the private collection of Professor Richard Klebs, who first interested Wheeler on working with Baltic amber ant specimens. Alongside ''A. sommerfeldti'', three other ''Aphaenogaster'' species are known from European amber fossil, '' A. antiqua'', '' A. mersa'', and '' A. oligocenica''. While both ''A. oligocenica'' and ''A. sommerfeldti'' are known from Baltic and

Bitterfeld 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 ...

, ''A. mersa'' has only been found in Baltic amber and ''A. antiqua'' from

Rovno amber Rivne amber, occasionally called Ukrainian amber, is amber found in the Rivne Oblast and surrounding regions of Ukraine and Belarus. The amber is dated between Late Eocene and Early Miocene, and suggested to be contemporaneous to Baltic amber. ...

Description

Overall ''Aphaenogaster sommerfeldti'' can be distinguished from the related Baltic amber species ''A. oligocenica'' in several ways. ''A. sommerfeldti'' individuals have an overall more sloped and curved

mesonotum The mesothorax is the middle of the three segments of the thorax of hexapods, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal), the mesosternum (ventral), and the mesopleuron (lateral) on ...

with the epinotum showing more tooth liked projections on the surface then seen in ''A. oligocenica''. The other Baltic amber species, ''A. mersa'', shows a more extensive amount of rugose structuring to the head, thorax, and body, with a reticulation in the structuring, while that of ''A. sommerfeldti'' is a longitudinal striate pattern. ''A. sommerfeldti'' shows a similar morphology to the living species '' A. subterranea'' from the warmer areas of southern Europe. The two species differ in the more upright spines on the epinotum of ''A. sommerfeldti''. The head capsule of ''A. sommerfeldti'' is slimmer with thinner antenna segments and more complex rugosity on the rear of the capsule.

References

{{Taxonbar, from=Q17497414 Lutetian insects Fossil ant taxa Fossil taxa described in 1868 Prehistoric insects of Europe †Aphaenogaster sommerfeldti Baltic amber