Myrmeciites

Myrmeciites Temporal range: Ypresian, 51Ma PreЄ Є O S D C P T J K Pg N ↓
Myrmeciities "incertae sedis" SR 05-03-01
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Tribe:	†incertae sedis
Genus:	†Myrmeciites Archibald, Cover, & Moreau, 2006
Species
see text

Myrmeciites is a form genus of extinct bulldog ants which contains three described species and two fossils not placed beyond the genus level.^[1] All three of the described species and one unplaced fossil are from British Columbia, Canada, while the second unplaced fossil is from Washington State, USA.^[1]

History and classification

Fossils of Myrmeciites were first studied and described by Bruce Archibald, Stefan Cover and Corrie Moreau of the Museum of Comparative Zoology in Cambridge, Massachusetts. They published their 2006 description of the form genus and species in an Annals of the Entomological Society of America journal article.^[1] The genus name is a combination of the subfamily name "Myrmeciinae" and the Latin suffix "ites", meaning "having the nature of", which commonly used in fossil taxon naming.^[1]

Included with the form genus description, the paper contained the description of Myrmeciites herculeanus, Myrmeciites(?) goliath, and Myrmeciites(?) tabanifluviensis.^[1]

Description

Archibald, Cover, and Moreau erected the form genus as an encompassing category for all fossil ants which, while belonging to the subfamily Myrmeciinae, lack details needed for placement in the described genera. This may be due to preservation quality or positioning of the individual ant resulting in details being obscured. As the Myrmeciites is a form genus it does not have a designated type species per the International Code of Zoological Nomenclature.^[1]

M. herculeanus

M. herculeanus was described from a single side of a compression fossil found at the Middle Ypresian McAbee Fossil Beds, Kamloops Group, near Cache Creek, British Columbia. The incomplete specimen, numbered UCCIPR L-18 F-974, is currently preserved in the paleontology collections housed at the Thompson Rivers University, Kamloops, British Columbia. Archibald, Cover, and Moreau coined the specific epithet "herculeanus" from the Latin name "Hercules" in reference to the notably sturdy and large morphology of the type specimen.^[1] The species is discernible from the other species of Myrmeciinae by its notably larger size, the worker caste ant being estimated at over 20 millimetres (0.79 in) in life. The shape of the petiole is distinct from other species and is similar in structure to the genus Prionomyrmex, though the shape and size of the mandibles is distinct. The size of the single know worker is larger than any of the studied queens, which in combination with Myrmeciinae queens being slightly larger than the other castes in a species indicates M. herculeanus is most likely a distinct species. Due to the incomplete nature of the type specimen the species was placed in Myrmeciites.^[1]

M.(?) goliath

The second species described from the McAbee Fossil Beds is M.(?) goliath and as with M. herculeanus, it is known from one specimen, though both the part and counterpart are known for M.(?) goliath. The holotype is included in the Thompson Rivers University, Kamloops, collections as UCCIPR L-18 F-999 and UCCIPRL-18 F-1000 for each side respectively.^[1] The species name "goliath" was chosen by Archibald, Cover and Moreau in reference to the mythological Goliath, due to the notable size of the ant.^[1] The holotype specimen is a partial worker or queen which is incomplete, with the a notable portion of the gaster missing. The species can be separated from other ants by the large size, the holotype approaching 3 centimetres (1.2 in). The only other Eocene ants in this size range are members of the genus Titanomyrma, that were formerly placed in Formicium.^[1][2] M.(?) goliath is distinguishable from Titanomyrma by the shape and structure of the antennae and length of the legs, which are notably shorter in Titanomyrma. Within Myrmeciinae, the size of M.(?) goliath and having a head that is smaller in proportion to the mesosoma then seen in the other species.^[1]

M.(?) tabanifluviensis

Unlike the other described Myrmeciites species, M.(?) tabanifluviensis is the only species not from the McAbee Fossil Beds. The holotype, currently deposited in the Courtenay and District Museum paleontology collections as "2003.2.10 CDM 034" was recovered from shale of an unnamed formation outcropping near the town of Horsefly, British Columbia. The specimen is incomplete with both the head and portions of the mesosoma and gaster missing. The adult had an estimated length in life of over 1.5 centimetres (0.59 in).^[1] Due to the incomplete nature of the specimen, and position of the preserved portions the gender is not identifiable, though the presence of wings indicates it to be a reproductive adult. The small size of the specimen, with a fore-wing length of approximately 12 millimetres (0.47 in) separates this species from other members of the British Columbia Myrmeciinae. The type locality for the species, near the Horsefly River, was the basis for Archibald, Cover and Moreau choosing the specific epithet tabanifluviensis, which a combination of the horsefly genus name Tabanus, the Latin word fluvius meaning "river" and the sufix -ensis meaning "origin" or "place".^[1]

Unplaced specimens

Two additional specimens were placed within the form genus but not into a specific species. The Courtenay and District Museum specimen "2003.2.9 CDM 03 a&b" is a 2 centimetres (20 mm) long partial male recovered from the Falkland site, near Falkland, British Columbia. The generally robust nature of the specimen excludes it from the genus Avitomyrmex, but the details needed for placement between the genera Ypresiomyrma and Macabeemyrma are not present. The Stonerose Interpretive Center specimen "SR 05-03-01" is a possible queen or worker which would have been an estimated 1.5 centimetres (15 mm) long in life. Due to the lateral preservation of the specimen, most characters for placing the specimen into one of the defined species are obscured or absent. The specimen was recovered from outcrops of the Klondike Mountain Formation north west of Republic, Washington.^[1]

References