Macabeemyrma

Macabeemyrma; Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Reconstruction of Macabeemyrma ovata head capsule
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmeciinae
Genus:	†Macabeemyrma
Species:	†M. ovata
Binomial name
	†Macabeemyrma ovata; Archibald, Cover, & Moreau, 2006

Macabeemyrma is an extinct

Nothomyrmecia macrops, but has not been conclusively assigned to any tribe, instead generally regarded as incertae sedis

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, preserved as a compression fossil in fine-grained shale.^[2] The shale is from fossiliferous outcrops at the McAbee Fossil Beds, part of an unnamed bed in the Kamloops group Tranquille Formation which outcrops east of Cache Creek in British Columbia, Canada.^[3] The holotype specimen was collected by an unknown person and donated to Thompson Rivers University in 2002.^[4]^[5] The specimen was described by Bruce Archibald, Stefan Cover and Corrie Moreau of Harvard University's Museum of Comparative Zoology, with their 2006 type description of the genus and species. The generic name Macabeemyrma is a toponym of the type locality at McAbee^[a] combined with the Greek myrmex, meaning "ant". The specific epithet ovata, from the Latin "ovatus" meaning "egg shaped", refers to the shape of the head capsule.^[6]

Archibald and colleagues originally classified Macabeemyrma as

synapomorphies) of the ant family, Formicidae, and thus argued Macabeemyrma could only be confidently classified as incertae sedis within the order Hymenoptera.^[7]^[8] A subsequent report describing new fossil myrmecines accepted the classification of Archibald and colleagues without comment on the views of Baroni Urbani.^[3]

The following

Nothomyrmecia macrops.^[10]

Myrmeciinae

Myrmecia

	Prionomyrmex janzeni

	Prionomyrmex longiceps

	Macabeemyrma

	Nothomyrmecia

Myrmeciinae

Archimyrmex

Myrmecia

	Prionomyrmex janzeni

	Prionomyrmex longiceps

	Macabeemyrma

	Avitomyrmex

	Ypresiomyrma

	Nothomyrmecia

Description

The overall body of the ant is poorly preserved and much of it is indistinct.[5] Macabeemyrma ovata is about 25 millimetres (0.98 in) 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 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. 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.^[8]^[11] Its elongated head and mandibles distinguish this species from those in the genus Ypresiomyrma, which are otherwise thought to have a close phylogenetic relationship 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.^[11]

Ecology

Archibald and colleagues suggested the life habits of Macabeemyrma ovata may have been similar to extant Myrmeciinae ants.^[12] 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 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.^[12]