''Bradoponera'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...

in the Formicidae subfamily

Proceratiinae Proceratiinae is a subfamily of ants in the poneromorph subfamilies group, with three extant genera, of which most are tropical or subtropical, although overall distribution is worldwide. Identification The ants are relatively small to medium i ...

, 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 The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

amber fossils which were found in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

History and classification

Individuals of ''Bradoponera'' species have been found as inclusions in two different

Early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...

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 Baltic may refer to: Peoples and languages * Baltic languages, a subfamily of Indo-European languages, including Lithuanian, Latvian and extinct Old Prussian *Balts (or Baltic peoples), ethnic groups speaking the Baltic languages and/or originati ...

Bitterfeld Bitterfeld () is a town in the district of Anhalt-Bitterfeld, Saxony-Anhalt, Germany. Since 1 July 2007 it has been part of the town of Bitterfeld-Wolfen. It is situated approximately 25 km south of Dessau, and 30 km northeast of Halle (S ...

and

Rovno amber Rivne amber, occasionally called Ukrainian amber, is amber found in the Rivne Oblast and surrounding regions of Ukraine and Belarus. The amber is dated between Late Eocene and Early Miocene, and suggested to be contemporaneous to Baltic amber. ...

s. Baltic amber is approximately 46 million years old, having been deposited during the

Lutetian The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...

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 ''Agathis'', commonly known as kauri or dammara, is a genus of 22 species of evergreen tree. The genus is part of the ancient conifer family Araucariaceae, a group once widespread during the Jurassic and Cretaceous periods, but now largely re ...

'' or ''

Pseudolarix ''Pseudolarix'' is a genus of coniferous trees in the pine family Pinaceae containing three species, the extant ''Pseudolarix amabilis'' and the extinct species '' Pseudolarix japonica'' and '' Pseudolarix wehrii''. ''Pseudolarix'' species are c ...

''. Rovno amber, recovered from deposits in the

Rivne Rivne (; uk, Рівне ),) also known as Rovno (Russian: Ровно; Polish: Równe; Yiddish: ראָוונע), is a city in western Ukraine. The city is the administrative center of Rivne Oblast (province), as well as the surrounding Rivne Raio ...

region of

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

and areas of western

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

, is slightly younger in age, being dated between the

Bartonian The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic definitio ...

of the

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "daw ...

to possibly

. 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 The Paratethys sea, Paratethys ocean, Paratethys realm or just Paratethys was a large shallow inland sea that stretched from the region north of the Alps over Central Europe to the Aral Sea in Central Asia. Paratethys was peculiar due to its pal ...

, 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 Gustav L. Mayr (12 October 1830 – 14 July 1908) was an Austrian entomologist and professor in Budapest and Vienna. He specialised in Hymenoptera, being particularly known for his studies of ants.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 The University of Königsberg (german: Albertus-Universität Königsberg) was the university of Königsberg in East Prussia. It was founded in 1544 as the world's second Protestant academy (after the University of Marburg) by Duke Albert of Prussi ...

. Much of the Königsberg collection was lost during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

with only a small portion of the collection, about 10%, rediscovered in the

University of Göttingen The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...

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 The Naturmuseum Senckenberg is a museum of natural history, located in Frankfurt am Main. It is the second-largest of its type in Germany. The museum contains a large and diverse collection of birds with 90,000 bird skins, 5,050 egg sets, 17,0 ...

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

epiphyte An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...

Description

''Bradoponera'' species are distinguished from other Proceratiinae genera by a combination of features. In queens and workers, the small eyes are composed of a small amount of

ommatidia The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The ou ...

and have a low to flat profile on the head. There are

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

present on queens and males, but ocelli are absent in workers. The antennae have either nine segments as in ''B. wunderlichi'' or twelve as in the other three species. In all species the expand in diameter from the base to the tip, and the final

flagellomere Antennae ( antenna), sometimes referred to as "feelers", are paired appendages used for sensing in arthropods. Antennae are connected to the first one or two segments of the arthropod head. They vary widely in form but are always made of one o ...

is inflated to form a large club. Frontal ridges form along the edges of the antennae sockets, curving down and apart from each other. The clypeus is curved outward along the front edge and separated from the antennae at the back edge by the frontal ridges. All species have triangular

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

that lack developed teeth on the chewing sides. The labial palps have four segments, while the maxillary palps have five, with the second segments from the maxilla curved rather than hammer shaped. The bodies of the workers and queens have a compact and very robust

mesosoma The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings. In hymenopterans of t ...

that is moderately convex along the top surface. With the workers there are no suture lines distinguishing the mesopropodeal or promesonotal sutures. The petioles have a node that is scale or wedge shaped when viewed from the side. A small exoskeletal plate, the helcium, is present, projecting forward from the middle of the first gastral segments front side. The

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

on the second gaster segment is very highly domed, which causes the remaining gasteral segments to curl down and forward. Only males of ''B meieri'' have been described. Generally they have smaller round heads with ocelli, large well developed eyes and a rounded rear margin to the head lacking occipital corners. The short frontal ridges do not cover the antennae bases. The antennae are long and string shaped, with thirteen segments that each have a bead-like outline. Males have the same shape and structure in their mandibles as queens and workers, but in males the closed mandibles do not touch each other. The terminal segment of the abdomen does not have a spine present. The forewings of males have venation that is incomplete, missing the mcu and rm cells while the hindwings do not have jugal lobes.

''B. electrina''

This species is identified from a single brownish-black worker with flat laying setae along the body and sparser semi-erect setae that are longer than the flat setae. The semi-erect setae are not seen in ''B. meieri'' ''B. similis'' or ''B. wunderlichi'', distinguishing ''B. electrina'' from workers of the other species. With an approximate total length of , ''B. electrina'' workers are the largest for any ''Bradoponera'' species. The ridges running from the eyes are smaller than seen in other species, and they do not cover the antennae bases. The eyes themselves are small with not much convexity and the

are separated from each other by hairs. The antennae are not as robust as other species, with scapes that protrude past the rear borders of the eyes. The mesosoma is slightly shorter than the head length, with a distinct suture line at the pronotum. The petiole node is scale shaped and nearly four times wider than long, double that of other ''Bradoponera'' species. The species name was coined by Baroni Urbani from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''electrinus'' which he translated as "made of amber".

''B. meieri''

''B. meieri'' male The type species for the genus, ''B. meieri'' is known from three castes, workers, queens, and males. There is little variation in the sizes of the workers, which have lengths ranging between . The bodies, legs and antennae have prolific slight erect to flat laying hairs. The exoskeleton of the head and upper surface of the mesosoma have evenly spaced pits that are about the same diameter as the spacing between the pits. The pits grow smaller and further apart on the gaster, and are partially by the dense flat laying hairs. The rounded rectangular heads have round shallowly domed eyes and the head to mesosoma joint is ringed by a low exoskeletal ridge. The clypeus is distinctly divided into three sections, the large median area and two lateral sections. The lateral strips are narrow, running from the mandible bases up the sides of the median lobe. The median area is slightly rectangular, with the front edge flaring a little past the front edges of the lateral sections. along the back edge it is bordered by the two frontal ridges and the antennae sockets. The antennae have widened flat scapes that reach between towards the back of the head, but not past it. The upper end of the scape has an uneven top with a divot possibly for the base of flagellum when it was at rest. Excluding the last

, all the segments after the scape are as wide or wider than long, while the tip flagellomere is enlarged to equal the lengths of flagellomeres ten to three.

''B. similis''

The single described worker of ''B. similis'' has an estimated body length of . The head has an outline has rounded corners at the rear and the back margin is either slightly concave or straight. There is a raised ridge of exoskeleton that borders the eyes while the eyes themselves are larger than the compound eyes of ''B. meieri'' workers. The mesosoma has no visible sutures between the exoskeleton plates, is narrower than tall, and the upper surface has a smooth rounded outline with no indent at the mesopropodem. The head is a rounded rectangular shape, being shorter than long, and a flat to slightly bowed rear margin.

''B. wunderlichi''

Bradoponera wunderlichi SMFBE524 profile

The species was described from a single wingless female that is approximately long. The female has antennae possessing 9 segments, three less than seen in ''B. meieri'' queens. The antennae have thick scapes that reach just past the rear margins of the eyes. The basal two antenna segments after the scape are both roughly square in outline, while the next five segments are shorter than wide with a rectangular outline. The mandibles have an overall triangular outline, with a convex curvature to the outside edges and smooth, toothless chewing edges. The dark brownish-black body is covered in fine setae that lay against the exoskeleton. Unlike ''B. electrina'' the robust mesosoma is approximately the same length as the head including mandibles. The petiole is short and wide, the width being about double the length in profile, and the frond and rear sides narrow slightly towards the base giving a wedge like outline. The species epithet "wunderlichi" was chosen by Baroni Urbani as an epithet honoring Jörg Wunderlich, who supplied several of the fossils for examination.

References

External links

* {{Taxonbar, from=Q16533301 Proceratiinae Ant genera Eocene insects Fossil taxa described in 2009 Fossil taxa described in 2003 Fossil taxa described in 1865 Prehistoric insects of Europe Hymenoptera of Europe Baltic amber Rovno amber