''Macabeemyrma'' 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 n ...
of
bulldog ants in the subfamily
Myrmeciinae
Myrmeciinae is a subfamily of the Formicidae, ants once found worldwide but 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 a ...
containing the single species ''Macabeemyrma ovata'', described in 2006 from
Ypresian stage (
Early Eocene
In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...
) deposits of British Columbia, Canada. Only a single specimen is known; a holotype queen found preserved as a compression fossil. The specimen had no wings and small portions of its legs and eyes were faintly preserved. It was a large ant, reaching in length. This ants' behaviour would have been similar to that of extant Myrmeciinae ants, such as foraging singly in search for arthropod prey and nesting in soil or in trees. ''Macabeemyrma'' shows similarities to extinct ants in the genus ''
Ypresiomyrma'', and to the living ''
Nothomyrmecia macrops'', but has not been conclusively assigned to any tribe, instead generally regarded as ''
incertae sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...
'' within Myrmeciinae. However, the sole specimen lacks definitive traits, and its classification in Myrmeciinae, and even its identity as an ant, has been challenged.
History and classification

''Macabeemyrma ovata'' is known only from a single fossil specimen: a mostly complete adult
queen
Queen or QUEEN may refer to:
Monarchy
* Queen regnant, a female monarch of a Kingdom
** List of queens regnant
* Queen consort, the wife of a reigning king
* Queen dowager, the widow of a king
* Queen mother, a queen dowager who is the mother ...
, preserved as a
compression fossil
A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason f ...
in fine-grained
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...
. The shale is from fossiliferous outcrops at the
McAbee Fossil Beds
The McAbee Fossil Beds is a Heritage Site that protects an Eocene Epoch fossil locality east of Cache Creek, British Columbia, Canada, just north of and visible from Provincial Highway 97 / the Trans-Canada Highway ( Highway 1). The McAbee Fo ...
, part of an unnamed bed in the Kamloops group
Tranquille Formation which outcrops east of
Cache Creek in British Columbia, Canada.
The holotype specimen was collected by an unknown person and donated to
Thompson Rivers University
Thompson Rivers University (commonly referred to as TRU) is a public teaching and research university offering undergraduate and graduate degrees and vocational training. Its main campus is in Kamloops, British Columbia, Canada, and its na ...
in 2002. The specimen was described by Bruce Archibald, Stefan Cover and Corrie Moreau of Harvard University's
Museum of Comparative Zoology
A museum ( ; plural museums or, rarely, musea) is a building or institution that cares for and displays a collection of artifacts and other objects of artistic, cultural, historical, or scientific importance. Many public museums make thes ...
, with their 2006
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 ...
of the genus and species. The
generic name ''Macabeemyrma'' is a
toponym
Toponymy, toponymics, or toponomastics is the study of '' toponyms'' ( proper names of places, also known as place names and geographic names), including their origins, meanings, usage and types. Toponym is the general term for a proper name o ...
of the type locality at McAbee combined with the Greek ', meaning "ant". The specific epithet ''ovata'', from the Latin "''ovatus''" meaning "egg shaped", refers to the shape of the head capsule.
Archibald and colleagues originally classified ''Macabeemyrma'' as ''
incertae sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...
'' (Latin for "of uncertain placement") within the ant subfamily
Myrmeciinae
Myrmeciinae is a subfamily of the Formicidae, ants once found worldwide but 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 a ...
, as it could not be confidently placed into any ant
tribe
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...
. However, in a 2008 paper, Cesare Baroni Urbani of the
University of Basel
The University of Basel (Latin: ''Universitas Basiliensis'', German: ''Universität Basel'') is a university in Basel, Switzerland. Founded on 4 April 1460, it is Switzerland's oldest university and among the world's oldest surviving universitie ...
, Switzerland, noted that the specimen shares some traits found in other ant subfamilies and some
wasps
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...
, and lacks key diagnostic traits (
synapomorphies
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...
) of the ant family, Formicidae, and thus argued ''Macabeemyrma'' could only be confidently classified as ''incertae sedis'' within the order
Hymenoptera.
A subsequent report describing new fossil myrmecines accepted the classification of Archibald and colleagues without comment on the views of Baroni Urbani.
The following
cladograms
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
generated by Archibald and colleagues show two possible
phylogenetic position
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...
s of ''Macabeemyrma'' among some ants of the subfamily Myrmeciinae; the cladogram on the right included three additional extinct genera compared to that on the left. They suggest that ''Macabeemyrma ovata'' and other extinct ants such as ''Avitomyrmex'' and ''Ypresiomyrma'' may be closely related to the living ''
Nothomyrmecia macrops''.
Description
The overall body of the ant is poorly preserved and much of it is indistinct. ''Macabeemyrma ovata'' is about long with a distinct elongated oval head capsule that is about 1.5x longer than wide. The holotype is missing the wings and some portions of the legs while 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 c ...
are very faintly preserved. It could not be confirmed whether its eyes were compound or not, but if it was to be confirmed they would share similar eye characteristics to ''
Myrmecia
Myrmecia can refer to:
* ''Myrmecia'' (alga), genus of algae associated with lichens
* ''Myrmecia'' (ant), genus of ants called bulldog ants
* Myrmecia (skin), a kind of deep wart on the human hands or feet
See also
* '' Copromorpha myrmecias'' ...
''. The exact shape of the mandibles cannot be properly determined, but they are elongated and not subtriangular which is normal for other members of Myrmeciinae except the genus ''Myrmecia''.
[ Its elongated head and mandibles distinguish this species from those in the genus ''Ypresiomyrma'', which are otherwise thought to have a close ]phylogenetic relationship
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
due to similarities. The waist consists of a single segment, and whether or not the ant has a sting cannot be fully determined due to the condition of the specimen collected.
Ecology
Archibald and colleagues suggested the life habits of ''Macabeemyrma ovata'' may have been similar to extant Myrmeciinae ants. The ant is large with long legs and elongated mandibles. It presumably had large eyes that were used to hunt for prey and navigation, and the ant was possibly equipped with a sting. Colonies most likely nested in the soil like most other Myrmeciinae, but like some ''Myrmecia'' species it is possible they were an arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...
nesting species. Workers were solitary foragers, foraging on the ground or onto vegetation while preying on arthropods. Workers most likely did not recruit other ants to food sources or lay down pheromone trails.
Notes
References
Cited text
External links
*
''Macabeemyrma'' at the AntWiki – Bringing Ants to the World
''Macabeemyrma''
at AntCat
{{Taxonbar, from=Q6722393
Myrmeciinae
Fossil taxa described in 2006
†
A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species). It is one of the modern descendan ...
Monotypic fossil ant genera
Prehistoric insects of North America
Ypresian insects
Tranquille Formation