Bradoponera is an extinct genus of ant in the Formicidae subfamily Proceratiinae, and is one of four genera of the subfamily. The genus contains four described species Bradoponera electrina, Bradoponera meieri, Bradoponera similis, and Bradoponera wunderlichi. The species are known from several Middle Eocene amber fossils which were found in Europe.
History and classification
Individuals of Bradoponera species have been found as inclusions in two different Middle Eocene to Early Oligocene amber deposits in Europe. The species B. electrina and B. wunderlichi are known from Baltic amber, while B. similis is known from Bitterfield amber only. The type species B. meieri is the most wide spread of the four species, with individuals identified from Baltic, Bitterfeld and Rovno ambers.
Baltic amber is approximately 46 million years old, having been deposited during the Lutetian stage of the Middle Eocene. There is debate on what plant family the amber was produced by, with evidence supporting them being relatives of either Agathis or Pseudolarix.
Rovno amber, recovered from deposits in the Rivne region of Ukraine and areas of western Poland, is slightly younger in age, being dated between the Bartonian of the Late Eocene to possibly Early Oligocene.
Bitterfeld amber is recovered from coal deposits in the Saxony area of Germany and the dating of the deposits is uncertain. Bitterfeld represents a section of the Eocene Paratethys Sea, and the amber that is recovered from the region is thought to be redeposited from older sediments. The fossil record of Bitterfeld and Baltic amber insects is very similar with a number of shared species, and that similarity is noted in the suggestions of a single source for the paleoforest that produced the amber.
The genus was first described in 1868 by the Austrian entomologist Gustav Mayr with Mayr's 1868 type descriptions of the new genus and species being published in the journal Beiträge zur Naturkunde Preussens. B. meieri was described from several workers and the type series of fossils were placed into the amber collections of the University of Königsberg. Much of the Königsberg collection was lost during World War II with only a small portion of the collection, about 10%, rediscovered in the University of Göttingen collections.
Both B. electrina and B. wunderlichi are described from single fossils. The two type specimens and three B. meieri workers were examined and described by paleomyrmecologists Maria L. De Andrade and Cesare Baroni Urbani. The five specimens were originally in the private collection of Jörg Wunderlich who subsequently allowed the fossils to be purchased by the Museo Regionale di Scienze Naturali of Turin. Baroni Urbani described both species in a 2003 Revue Suisse de Zoologie paper. At some point after 2003 both the B. electrina and B. wunderlichi type specimens were transferred to the Senckenberg Museum in Germany.
In 2009 a fourth species, B. similius from Bitterfeld amber, was described and placed into the genus. The single described worker, specimen HM 11/388, was housed in the Natural History Museum of Berlin while being studied. The species was erected by Russian paleoentomologist Gennady Dlussky in a paper on Late Eocene amber ant species, but no etymology for the species was provided in the paper.
Paleoecology
The suggested habitat of Bradoponera differs from the other members of Proceratiinae. Species of the three living genera nest and live in the soft upper forest floor litter. As such the workers are not found on tree trunks or in the canopies. Bradoponera fossils are predominantly workers, which indicate the species was not likely to be nesting on the ground but arboreally. Given the rounded heads and lack of strong chewing mandibles, Dlussky hypothesized the colony nests to have been in preexisting cavities of the tree, or more likely, in debris and soils accumulating around epiphytes.