Avitomyrmex is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of bulldog ants

Myrmeciinae

The Myrmeciinae is a subfamily of the Formicidae that was once found worldwide but is now restricted to Australia and New Caledonia. This subfamily is one of several ant subfamilies which possess gamergates, female worker ants which are able to mate and reproduce, thus sustaining the colony after...

 which contains three described species. All three of the described species are from British Columbia, Canada.

History and classification

Fossils of Avitomyrmex were first studied and described by Bruce Archibald, Stefan Cover and Corrie Moreau of the Museum of Comparative Zoology

Museum of Comparative Zoology

The Museum of Comparative Zoology, full name "The Louis Agassiz Museum of Comparative Zoology", often abbreviated simply to "MCZ", is a zoology museum located on the grounds of Harvard University in Cambridge, Massachusetts. It is one of three museums which collectively comprise the Harvard Museum...

 in Cambridge, Massachusetts

Cambridge, Massachusetts

Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...

. They published their 2006 description of the genus and species in an Annals of the Entomological Society of America journal article. The genus name is a combination of the Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 "avitus" meaning "ancient" or "grandfatherly" and the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 myrmex, meaning "ant".

Included with the genus description, the paper contained the description of Avitomyrmex mastax, Avitomyrmex systenus, and the type species Avitomyrmex elongatus.

Description

There are several characters which separate Avitomyrmex from other ant genera. The most notable feature is the distinctly slender nature of the queens and workers morphology. This is shown clearly in the shape of the waist connecting the thorax

Thorax (insect anatomy)

The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....

 and the abdomen

Gaster

The gaster is the bulbous posterior portion of the metasoma found in Apocrita Hymenoptera . This begins with abdominal segment III on most ants, but some make a postpetiole out of segment III, in which case the gaster begins with abdominal segment IV....

. While similar to the modern myrmeciin genus Nothomyrmecia of Southern Australia, the two genera are distinguishable by the structure of the petiole, with Avitomyrmex lacking the peduncle seen in Nothomyrmecia.

A. elongatus

A. elongatus was described from a single side of a compression fossil found at the Middle Ypresian

Ypresian

In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....

 McAbee locality, Kamloops Group, near Cache Creek, British Columbia

Cache Creek, British Columbia

Cache Creek is a junction community northeast of Vancouver in British Columbia, Canada. It is on the Trans-Canada Highway in the province of British Columbia at its junction with northbound Highway 97...

. The incomplete specimen, numbered 2003.2.8CDM032, is currently preserved in the paleontology

Paleontology

Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...

 collections housed at the Courtenay and District Museum, Courtenay, British Columbia

Courtenay, British Columbia

Courtenay is a city on the east coast of Vancouver Island, in the Canadian province of British Columbia. It is the largest city in the area commonly known as the Comox Valley, and it is the seat of the Comox Valley Regional District which replaced the Comox-Strathcona Regional District...

. Archibald, Cover, and Moreau coined the specific epithet

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 from the Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 "elongatus" meaning "prolonged" in reference to the elongated morphology of the type specimen. The species is discernible from the other two species of Avitomyrmex by its notably larger size, the preserved portion of the ant being over 20 millimetre (0.78740157480315 in). The holotype queen is preserved with a partly disarticulated gaster and is missing her head.

A. mastax

The second species described from the McAbee site is A. mastax which, unlike A. elongatus, is known from a two specimens. The holotype and paratype are both included in the Thompson Rivers University

Thompson Rivers University

Thompson Rivers University is a comprehensive university located in Kamloops, British Columbia, Canada. It offers students a broad range of courses, career streams, and the ability to ladder credits from diploma programs into full degrees...

, Kamloops, collections as UCCIPRL-18 F-850 and UCCIPRL-18 F-929 respectively. The holotype specimen is a partial queen which is incomplete, with one fore-wing and the head fairly preserved, and the other isolated body portions indistinct. The paratype is a mostly complete queen missing parts of her gaster, legs and hind wings. Overall the species is estimated to have been 15 millimetre (0.590551181102362 in) long and has a fore-wing length of 13 millimetre (0.511811023622047 in). A. mastax is distinguishable from the other species in Avitomyrmex by its smaller mandible size and additionally the shape of the head capsule. The specific epithet mastax is from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 "mastax" meaning "jaw" or "mandible", a reference to the small size of the mandibles compared to the other species of Avitomyrmex.

A. systenus

Of the three described species of Avitomyrmex found at the McAbee site, only A. systenus is known from worker caste specimens. The holotype is currently deposited in the Courtenay and District Museum paleontology collections as 2003.2.11 CDM 035 while the paratype, UCCIPR L-18 F-989, and an additional hypotype worker, UCCIPR L-18 F-825, which is tentatively assigned to the species are both deposited in Thompson Rivers University collections. Based on the mostly complete workers, mature specimens are estimated to have been 15 millimetre (0.590551181102362 in). Due to the size of adult workers they cannot be attributed to A. elongatus, while the overall petiole, head capsule and mandible structure distinguish it from A. mastax. The shape of the head was the basis for Archibald, Cover and Moreau choosing the specific epithet systenus, which is from the Greek word systenos meaning "tapering to a point".