Sphecomyrminae

Sphecomyrminae is an extinct subfamily of ants in family Formicidae known from a series of Cretaceous fossils found in North America, Europe, and Asia. Sphecomyrminae, is divided into two tribes, Haidomyrmecini and Sphecomyrmini with a total of nine genera. The tribe Haidomyrmecini contains the three genera Haidomyrmex, Haidomyrmodes and Haidoterminus while Sphecomyrmini contains Baikuris, Cretomyrma, Dlusskyidris, Sphecomyrma, and Sphecomyrmodes, with the genus Zigrasimecia unplaced at the tribal level.

Sphecomyrminae is the most basal of the Formicidae subfamilies, but has not been included in several recent phylogenetic studies of the family. Symplesiomorphies of the subfamily include the structure of the antenna which has a short basal segment and a flexible group of segments below the antenna tip. The petiole is low and rounded, with an unrestricted gaster and the presence of a metapleural gland. The subfamily is characterized by three major synapomorphies, the short pedicel, on combination with a second flagellar segment that is double the length of the other antenna segments, and loss of the apical end of the CuA veins in the wings of adult males.

History and classification
The single Haidomyrmodes species, Haidomyrmodes mammathus, is known from fossil insects which are inclusions in transparent chunks of French amber. The genus was first described by paleoentomologists Vincent Perrichot and André Nel in 2008. The sister genus, Haidomyrmex is more diverse with three described species, Haidomyrmex cerberus, Haidomyrmex scimitarus and Haidomyrmex zigrasi, all described from fossils in Burmese amber. While the type specimen of Haidomyrmex cerberus was collected in the early 1900s and deposited in the Natural History Museum in London, description of the specimen did not occur until 1996 with a paper by the Russian paleoentomologist Gennady M. Dlussky. Both H. scimitarus and H. zigrasi were described in the same 2012 paper by Phillip Barden and David Grimaldi. The third genus, Haidoterminus and its single species Haidoterminus cippus were described in 2013 from Canadian amber. This extended the age range for the tribe by an additional 20 million years into the Late Cretaceous the and expanded the geographic range into North America.

In the sphecomyrmins, Baikuris is known from four species. Both B. mandibularis, and B. miriabilis were described in 1987 by Dlussky from a group of fossil males found in Taymyr amber while the third species, B. casei, was described in 1997 from New Jersey amber. A fourth species was described from Charentes amber as B. maximus. Both Cretomyrma species, C. arnoldii and C. unicornis are also described from Taymyr amber specimens, with their descriptions being published by Dlussky in 1975. In the same descriptive paper as Cretomyrma was another new monotypic genus which Dlussky named "Palaeomyrmex", however this name was already preoccupied by Palaeomyrmex which Oswald Heer described in 1865 and the Taymyr amber genus was given a new name, Dlusskyidris, in 1994 by B. Bolton. Fossils belonging to the subfamily were first discovered in exposures of the Santonian Magothy Formation at Cliffwood Beach, New Jersey in 1966. The fossils were described in 1967 by Edward O. Wilson and William L. Brown, who placed the new genus Sphecomyrma  and species Sphecomyrma freyi into the new subfamily Sphecomyrminae. A second species of Sphecomyrma was described by Wilson in 1985 based on fossils found in Canadian amber from the Foremost Formation in Alberta. The third known species, S. mesaki was described in 2005 from New Jersey amber of the Raritan Formation. The last genus in the tribe is Sphecomyrmodes which was first described in the same 2005 paper as Sphecomyrma mesaki. Initially it contained the single species Sphecomyrmodes orientalis based on fossils from Burmese amber, and in 2007 a second species, Sphecomyrmodes occidentalis was added to the genus. Sphecomyrmodes occidentalis is the only species in the tribe Sphecomyrmini that has been described from European fossils.

The eighth genus of the subfamily, Zigrasimecia was studied by Barden and Grimaldi with its description being published in 2013. The genus contains the single species Zigrasimecia tonsora which is known from a solitary dealate female preserved in Burmese amber. While noting the close relationship between Zigrasimecia and Sphecomyrmodes, Barden and Grimaldi did not specifically place Zigrasimecia into any Sphecomyrminae tribe.

Tribes and genera

 * Sphecomyrminae Wilson & Brown, 1967
 * Haidomyrmecini Bolton, 2003
 * Haidomyrmex Dlussky, 1996
 * Haidomyrmodes Perrichot, Nel, et al., 2008
 * Haidoterminus McKellar, Glasier & Engel, 2013
 * Sphecomyrmini Wilson, Carpenter & Brown, 1967
 * Baikuris Dlussky, 1987
 * Cretomyrma Dlussky, 1975
 * Dlusskyidris Bolton, 1994
 * Sphecomyrma Wilson & Brown, 1967
 * Sphecomyrmodes Engel & Grimaldi, 2005
 * Zigrasimecia Barden & Grimaldi, 2013