Avitomyrmex

All Avitomyrmex specimens were collected from the McAbee Fossil Beds, British Columbia

Avitomyrmex is an extinct genus of ants with three described species.[2] Fossils of Avitomyrmex, along with other extinct Myrmeciinae ants 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 genus and species in an Annals of the Entomological Society of America journal article.[3] The genus name is a combination of the Latin "avitus" meaning "ancient" or "grandfatherly" and the Greek myrmex, meaning "ant".[2]

Included with the genus description, the paper contained the description of Avitomyrmex mastax, Avitomyrmex systenus, and the type species Avitomyrmex elongatus.[4] These fossil species date back to the Middle Ypresian.[3]

Archibald and colleagues originally classified Avitomyrmex as incertae sedis (Latin for "of uncertain placement") within the ant subfamily Myrmeciinae, as the specimens are unable to be properly identified.[5] In 2008, however, Cesare Baroni Urbani of the University of Basel, Switzerland, noted that no specimen in this genus allows a proper examination of the apomorphy (key diagnostic traits) of the subfamilial or familial characters. While Baroni Urbani excludes Avitomyrmex from Myrmeciinae and classifies it as incertae sedis in Hymenoptera, the morphological characters and wings show the specimens are undoubtedly a hymenopteran insect.[6] A 2012 report by Russian palaeoentomologist Gennady M. Dlussky of the Moscow State University describing new Myrmeciinae accepted the classification of Archibald and colleagues without mentioning the comments of Baroni Urbani.[7]

The following cladograms generated by Archibald and colleagues show two possible phylogenetic positions of Avitomyrmex among some ants of the subfamily Myrmeciinae; the cladogram on the right included three additional extinct genera compared to that on the left. It is suggested that Avitomyrmex may be closely related to other extinct Myrmeciinae ants such as Macabeemyrma and Ypresiomyrma, as well as the extant Nothomyrmecia macrops.[8]

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 petiole connecting the thorax and the abdomen. While similar to the modern myrmeciine genus Nothomyrmecia of Southern Australia, the two genera are distinguishable by the structure of the petiole, with Avitomyrmex lacking the peduncle seen in Nothomyrmecia. The eyes are large and well developed, the mandibles are subtriangular but poorly preserved, and a sting is present on examined A. systenus fossils.[2] As for A. elongatus and A. mastax, it is unknown if the two ants have a sting, due to either poor preservation or the sting has not been preserved at all.[9][10]

Archibald and colleagues suggested that the life habits of Avitomyrmex species may have been similar to that of extant Myrmeciinae ants. These ants may have nested in the soil or in trees, possibly being an arboreal nesting genus. This may be the case as one Myrmecia species is known to inhabit trees exclusively. Workers most likely preyed on arthropods, killing them with their sting and fed on nectar; workers would have been found foraging onto trees or low vegetation without leaving any pheromone trails to food sources or recruit nestmates, as they were solitary foragers. Avitomyrmex ants most likely used their large eyes to locate prey and for navigational purposes.[13]

• Data related to Avitomyrmex at Wikispecies
• Avitomyrmex at the AntWiki – Bringing Ants to the World
• Avitomyrmex at AntCat