''Proceratium eocenicum'' 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 of formicid in the ant subfamily

Proceratiinae Proceratiinae is a subfamily of ants in the poneromorph subfamilies group, with three extant genera, of which most are tropical or subtropical, although overall distribution is worldwide. Identification The ants are relatively small to medium i ...

known from fossils found in the Baltic region.

History and classification

''P. eocenicum'' is known from two fossil specimens of adult males. The fossils were discovered preserved as inclusions in transparent chunks of Baltic amber. Baltic amber is approximately forty six million years old, having been deposited during Lutetian stage of the Middle Eocene. There is debate on what plant family the amber was produced by, with macrofossil and microflossil evidence suggesting a '' Pinus'' relative, while chemical and spectroscopic evidence suggests ''

Agathis ''Agathis'', commonly known as kauri or dammara, is a genus of 22 species of evergreen tree. The genus is part of the ancient conifer family Araucariaceae, a group once widespread during the Jurassic and Cretaceous periods, but now largely re ...

'' or ''

Sciadopitys ''Sciadopitys verticillata'', the or Japanese umbrella-pine, is a unique conifer endemic to Japan. It is the sole member of the family Sciadopityaceae and genus ''Sciadopitys'', a living fossil with no close relatives. The oldest fossils of ''S ...

''. The paleoenvironment of the Eocene Baltic forests where the ''P. eocenicum'' lived was that of humid temperate to subtropical islands. The forests were composed of mostly '' Quercus'' and ''Pinus'' species, while the lower sections of the forests had paratropical plant elements, such as palms. At the time of description, the holotype male, number MZ PAN, no. 18097 was preserved in the

Museum of the Earth The Museum of the Earth is a natural history museum located in Ithaca, New York. The museum was opened in 2003 as part of the Paleontological Research Institution (PRI), an independent organization pursuing research and education in the history o ...

collections, part of the Polish Academy of Sciences. The paratype male, (CGC, no. 3306) was part of the Carsten Gröhn private collection as CGC no.3306, and subsequently deposited in the Geological-Paleontological Institute and Museum at the University of Hamburg as specimen GPIH, no. 4507. The fossil was first described by the Russian paleomyrmecologist Gennady Dlussky in a paper on the ant subfamilies Ponerinae, Cerapachyinae, and

Pseudomyrmecinae Pseudomyrmecinae is a small subfamily of ants containing only three genera of slender, large-eyed arboreal ants, predominantly tropical or subtropical in distribution. In the course of adapting to arboreal conditions (unlike the predominantly gro ...

in European Eocene ambers. In the type description, Dlussky named the species ''P. eocenicum'', 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 from "Eocene" as a reference to the age of the amber. As of 2015, six species of '' Proceratium'' had been described from fossils. '' P. denticulatum'', '' P. dominicanum'', '' P. gibberum'' and '' P. poinari'' are younger than ''P. eocenicum'', being described from the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

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 incl ...

. '' P. petrosum'', the first species to be described from a compression fossil, is from diatomite deposits of the Bol’shaya Svetlovodnaya site on the Pacific coast of Russia. ''P. eocenicum'' is of similar age to ''P. petrosum'', the only other species with a described fossil male.

Description

''P. eocenicum'' males range between in adult length, with a shiny exoskeleton. The surface of the exoskeleton has hairs, both upright and laying flat, and pitting across the whole body. The hairs are short, being shorter than the distance between each hair, while the upright hair is confined to areas of the legs, and around the tip of the gaster. The pits are not well developed on the head or the

scutum The ''scutum'' (; plural ''scuta'') was a type of shield used among Italic peoples in antiquity, most notably by the army of ancient Rome starting about the fourth century BC. The Romans adopted it when they switched from the military formati ...

, but become much more developed on the upper surface of the mesopleura and propodeum, spaced slightly closer than the diameter of each pit. Fore-wings on the males range between in length and have a distinct fringe of hair along the back edge of the wing.

References

External links

* {{Taxonbar, from=Q28340877 Proceratiinae Eocene insects Fossil taxa described in 2009 Prehistoric insects of Europe Hymenoptera of Europe Baltic amber Fossil ant taxa