''Asymphylomyrmex'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 ...

s in the formicid subfamily

Formicinae The Formicinae are a subfamily within the Formicidae containing ants of moderate evolutionary development. Formicines retain some primitive features, such as the presence of cocoons around pupae, the presence of ocelli in workers, and little ...

. The genus contains a single described

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 ...

, ''Asymphylomyrmex balticus'' and is 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 ...

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 preserved ...

s which were found in Europe.

History and classification

When described by

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 ...

, ''Asymphylomyrmex'' was known only from ten separate fossil ants, 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 sever ...

worker, number K4305, plus another nine workers which are fossilized as inclusions in transparent chunks of

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 ...

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

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 as to what plant family the amber was produced by, with evidence supporting relatives of either '' Agathis'' or ''

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 ...

'' genera trees. When first described, the type worker along with two other workers in a single amber piece, were in the private collection of Professor Richard Klebs of Königsberg University, who first interested Wheeler on working with Baltic amber ant specimens. The remaining seven workers were present in 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. All the specimens showed varying degrees of clouding in the amber or are in less than favorable positions for study. The fossils were first studied by Wheeler, then a paleoentomologist with

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...

, who placed the species in a new genus ''Asymphylomyrmex''. Wheeler's 1915

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 and genus was published in the journal ''Schriften der Physikalisch-Okonomischen Gesellschaft zu Königsberg''. Based on the structure of the head and thorax, and on the lack of spurs on the middle and hind tibia, Wheeler suggested that the species was a highly derived group which did not leave any descendants, having gone fully extinct. This group of characteristics led to erecting a new genus in Dolichoderinae rather than placing the species into an existing genus. A 2009 study on Central and Eastern European noted that at least one additional specimen of ''Asymphylomyrmex'' had been studied, 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. ...

in Northern Ukraine.

Description

It is estimated the workers would have been around long overall. ''A. balticus'' individuals have heads which are nearly orbicular, but slightly flattened on the rear portions. The

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...

are large, slightly rounded in cross section, and placed along the sides. The

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

are present but spaced far apart. The

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

are slender, straight near the base then curving inwards towards the tips. The apex and central areas of the mandibles have large teeth present, while the basal area behind the central tooth is finely serrate. The mouth is surrounded by both maxillary and labial palpi. The maxillary palpi have four joints, while the labial palpi are only three-jointed. The antennae are composed of twelve segments, the terminal segments flaring slightly forming an indistinct club shape. The head and thorax have a fine punctate structuring to the exoskeleton, and are coloured an overall ferruginous red. The thorax shows a widening at the join between the pronotum and the mesonotum, then slopes towards the epinotum.

References

{{Taxonbar, from1=Q18010739, from2=Q11686892 Monotypic fossil ant genera Lutetian insects Fossil taxa described in 1915 Prehistoric insects of Europe Formicinae Baltic amber Rovno amber