Brownimecia is an extinct genus of ants, the only genus in the tribe Brownimeciini and subfamily Brownimeciinae of the Formicidae. Fossils of the single identified species, Brownimecia clavata, are known from the Middle Cretaceous of North America. The genus is one of several ants described from Middle Cretaceous ambers of New Jersey. Brownimecia was initially placed in the subfamily Ponerinae, until it was transferred to its own subfamily in 2003; it can be distinguished from other ants due to its unusual sickle-like mandibles and other morphological features that makes this ant unique among the Formicidae. The ant is also small, measuring 3.43 millimetres (0.135 in), and a stinger is present in almost all of the specimens collected. The morphology of the mandibles suggest a high level of feeding specialization.
Brownimecia is known from three adult fossils: the holotype—specimen number AMNH NJ-667—collected by Yale Goldman; the paratype; and a third described in 2005.[1] At the time of the genus description, the type specimens were residing in the American Museum of Natural History, in New York City.[2] All the described specimens are worker caste adult females which have been preserved as inclusions in transparent chunks of New Jersey amber. The amber specimens were recovered from deposits of the South Amboy Fire Clay, part of the Raritan Formation. New Jersey amber has been dated to approximately 90 to 94 mya, placing it in the Turonian of the Late Cretaceous. Analysis of the amber composition indicates it originated as cupressaceous resins which were deposited in lagoons and salt water marshes along the Cretaceous eastern seaboard.[2] Brownimecia clavata is one of several ant species described from New Jersey amber, the others being Sphecomyrma freyi, Sphecomyrma mesaki, Baikuris casei, and Kyromyrma neffi.[1]
The type fossils were first studied by paleoentomologists David Grimaldi, Donat Agusti, and James Carpenter of the American Museum. The team's 1997 type description of the new genus and species was published in the journal American Museum Novitates.[2] The genus name was coined by them as a patronym honoring the ant systematist William L. Brown, Jr. who co-described the first Cretaceous ant genus and species Sphecomyrma freyi. The specific epithet clavata was chosen as a reference to the distinctive clubbed antennae seen in the workers. Grimaldi, Agusti, and Carpenter placed the new genus into the extant ant subfamily Ponerinae, without tribal assignment, based on a slight constriction of the gaster. They also noted several features that are shared with ants of the amblyoponine group, then a part of Ponerinae. The workers have genal spurs on the lower edge area under the small compound eyes. Workers also have narrow long mandibles, as do some amblyoponine genera. Placement in Ponerinae was unchanged until a revision of the subfamily was published in 2003 by myrmecologist Barry Bolton. In that paper the subfamily was shown to be a paraphyletic grouping and many of the included genera were moved to separate subfamilies, including the amblyoponines and Brownimecia. Due to the unique combination of morphological features found in Brownimecia, Bolton erected the new subfamily Brownimeciinae for the genus. Bolton notes that its sickle-like mandibles which lack teeth are not usual for ants and are often associated with dulotic, or slave-making, behavior in extant genera. In contrast to stem group ants such as the sphecomyrmines, the scapes of Brownimecia workers are more elongated like those of crown group ants.[1][3] In his 2007 phylogenetic examination of Formicidae, entomologist Philip Ward notes the possibility that Brownimecia is a crown group genus and placed the subfamily into the informal "poneroid" grouping in his phylogony.[4]