''Formicium'' is an extinct collective

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of giant

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 ...

s in the Formicidae subfamily

Formiciinae Formiciinae is an extinct subfamily of ants known from Eocene deposits in Europe and North America. Genera *Formiciinae Lutz, 1986 **Formiciini Lutz, 1986 ***''Titanomyrma'' Archibald, ''et al.'', 2011 ****''Titanomyrma gigantea'' (Lutz, 1986) ...

. The genus currently contains three species, ''Formicium berryi'', ''Formicium brodiei'', and ''Formicium mirabile''. All three species were described from Eocene aged sediments.

History and classification

The collective genus ''Formicium'' was first established by English entomologist and archaeologist John O. Westwood in 1854. and originally was only described from isolated fossil forewings, with full queens, drones, and workers being described from Germany later. From 1854 until 2010, the genus was expanded to include five

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), ...

, however the two German species were subsequently removed and placed in the related genus ''

Titanomyrma ''Titanomyrma'' is a genus of extinct giant ants which lived during the Eocene. The type species ''Titanomyrma gigantea'' and the smaller ''Titanomyrma simillima'' are known from the Eocene of Germany, while the third species ''Titanomyrma lubei' ...

'' as ''T. giganteum'' and ''T. simillimum''. The species ''Formicium mirabile'', named by Theodore D. A. Cockerell in 1920, and ''Formicium brodiei'', named by Westwood in 1854, are both known from fore-wings recovered from

middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

Bagshot Formation In geology, the Bagshot Beds are a series of sands and clays of shallow-water origin, some being fresh-water, some marine. They belong to the upper Eocene formation of the London and Hampshire basins, in England and derive their name from Bagsh ...

Bournemouth Bournemouth ( ) is a coastal resort town in the Bournemouth, Christchurch and Poole unitary authority area, in the ceremonial county of Dorset, England. At the 2021 census, the built-up area had a population of 196,455, making it the largest ...

Dorset, England Dorset ( ; archaically: Dorsetshire , ) is a ceremonial county in South West England. It is bordered by Somerset to the north-west, Wiltshire to the north and the north-east, Hampshire to the east, the Isle of Wight across the Solent to th ...

. The third species named, ''Formicium berryi'' was described by Frank M. Carpenter in 1929 from the middle Eocene Claiborne Formation in Puryear, Tennessee, USA, though he misidentified the formation as the

Wilcox Formation The Wilcox Formation is a Formation (geology), geologic formation in Vermont that is part of the Holly Mountain Complex. It is exposed within the western parts of Mendon, Vermont, Mendon and Shrewsbury, Vermont. The Type locality (geology), type ...

. ''F. berryi'' was the first described occurrence of the genus and, until 2011, the subfamily, in North America. As the wing structure of Formicidae is very plastic and can vary greatly, even within a species and size between males and females can be notably different, the description of fossil species from wings alone is problematic. With the removal of the two German species described from full body fossils in 2011, Dr. Bruce Archibald and coauthors changed ''Formicium'' from a nominal genus to collective genus. They suggested it be used to contain species described from wings which do not have enough detail to place into a nominal genus such as ''Titanomyrma''. As a collective genus, it does not contain a

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

per the

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...

, but is still retained as the type genus for the subfamily Formiciinae. ''Formicium berryi'' was originally described as ''Eoponera berryi'' by Frank Carpenter and placed in the

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

subfamily

Ponerinae Ponerinae, the ponerine ants, is a subfamily of ants in the Poneromorph subfamilies group, with about 1,600 species in 47 extant genera, including '' Dinoponera gigantea'' - one of the world's largest species of ant. Mated workers have replac ...

. This was based on the idea that the new species was related to the modern genus '' Dinoponera''. When initially described by Theodore D. A. Cockerell, ''Formicium mirabilis'' was placed in the monotypic genus ''Megapterites''. At that time he considered the species to be part of the family Pseudosiricidae. This placement was retained in the

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

Hymenoptera section written by Frank Carpenter. This placement, however did not reflect the changes made by German paleoentomologist

Herbert Lutz Herbert may refer to: People * Herbert (musician), a pseudonym of Matthew Herbert * Herbert (given name) * Herbert (surname) Places Antarctica * Herbert Mountains, Coats Land * Herbert Sound, Graham Land Australia * Herbert, Northern Territory ...

who synonymized ''Eoponera'' into ''Formicium'' in 1986 while describing the subfamily Formiciinae and the two German species. His 1990 synonymy of ''Megapterites'' into ''Formicium'' was also not reflected in the Treatise. Currently both genus names, ''Megapterites'' and ''Eoponera'' are accepted as junior synonyms of ''Formicium''.

Description

''F. berryi''

''F. berryi'' is only known from a forewing long and wide. It was collected by professor E.W. Berry of the

Johns Hopkins University The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

. Owing to the wings size, Carpenter believed that the ant may have been long, making it one of the largest ants to ever live. It has a long and narrow stigma (small, colored thick area near the wing-tip), and the discoidal cell is triangular. The apex is absent on the wing, but a complete shape of the wing may resemble that of '' Myrmecia''. The wings have similar dimensions to '' Dinomyrmex gigas'', a giant ant found in

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

''F. brodiei''

''F. mirabile''

The ''F. mirabile'' holotype is an incomplete forewing of preserved length, and at least a estimated length in life. The specimen and its counterpart were collected by J. S. Gardner and added to the

British Museum The British Museum is a Museum, public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is the largest in the world. It documents the story of human cu ...

paleontology collections as specimen "I.2596".

References

{{Taxonbar, from=Q5470186 Formiciinae Lutetian insects Eocene insects of North America Eocene insects of Europe Hymenoptera of Europe Hymenoptera of North America Fossil ant genera Fossil taxa described in 1854 Taxa named by John O. Westwood Lutetian genera