Haidomyrmex

Haidomyrmex is an extinct genus of ants in the formicid subfamily Haidomyrmecinae, and is one of nine genera placed in the subfamily Haidomyrmecinae. The genus contains three described species Haidomyrmex cerberus, Haidomyrmex scimitarus, and Haidomyrmex zigrasi. All three are known from single Late Cretaceous fossils which have been found in Asia. H. cerberus is the type species and Haidomyrmex the type genus for the subfamily Haidomyrmecinae.

==History and classification== Haidomyrmex, is known from three solitary adult fossil specimens which are composed of mostly complete adult females which have been preserved as an inclusions in transparent chunk of Burmese amber. The amber specimens entombing H. scimitarus, and H. zigrasi were recovered from deposits in Kachin State, west of Myitkyna town in Myanmar. In contrast, type specimen of H. cerberus was collected in the early 1900s from an unspecified location in Myanmar. Burmese amber has been radiometrically dated using U-Pb isotopes, yielding an age of approximately 99 million years old, close to the boundary between the Aptian and Cenomanian. The amber is suggested to have formed in a tropical environment around 5° north latitude and the resin to have been produced by either an Araucariaceae or Cupressaceae species tree. The mandibles of Haidomyrmecini genera are unique among ants in having a movement along the vertical plane. All other species with a trap-jaw type mandible structure show movement along the horizontal plane. Barden and Grimaldi suggest that the mandibles may have been capable of opening up to between 140° and 180°, if 0° is a closed position with the mandible tips near the clypeus. The resulting gape that results from the open position is nearly twice the head capsule diameter. The long legs and antennae are both features seen in arboreal ant species, and it has been suggested that the species may have nested in preexisting cavities in trees.thumb|right|upright|Haidomyrmex cerberus holotype workers head