''Paraneuretus'' 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 ...
of
formicid in the ant subfamily
Aneuretinae
Aneuretinae is a subfamily of ants consisting of a single extant species, ''Aneuretus simoni'' ( Sri Lankan relict ant), and 9 fossil species. Earlier, the phylogenetic position of ''A. simoni'' was thought to be intermediate between primitive a ...
known from fossils found in Asia and Europe. The genus contains three middle to late Eocene age species, ''Paraneuretus dubovikoffi'', ''Paraneuretus longicornis'', and ''Paraneuretus tornquisti''.
History and classification
''Paraneuretus'' is known from over twenty five adult fossil specimens which are composed of complete adult males, female workers and queens. The first fossils were discovered preserved as
inclusion
Inclusion or Include may refer to:
Sociology
* Social inclusion, aims to create an environment that supports equal opportunity for individuals and groups that form a society.
** Inclusion (disability rights), promotion of people with disabiliti ...
s in transparent chunks of
Baltic amber
The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite. It was produced sometime during the Eocene epoch, but exactly when is controversial. It has been estimated that these forests created more than 1 ...
.
Baltic amber is approximately forty six million years old, having been deposited during
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
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 ...
. There is debate on what plant family the amber was produced by, with evidence supporting relatives of either ''
Pinus
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
'', ''
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 ''
Sciadopitys
''Sciadopitys verticillata'', the or Japanese umbrella-pine, is a unique conifer endemic to Japan. It is the sole member of the family Sciadopityaceae and genus ''Sciadopitys'', a living fossil with no close relatives. The oldest fossils of ''S ...
''.
The paleoenvironment of the Eocene Baltic forests were two ''Paraneuretus'' species lived was humid temperate to subtropical islands. The forests were composed of mostly ''
Quercus
An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...
'' and ''Pinus'' species, while the lower sections of the forests had paratropical plant elements, such as
palms.
When first described the type specimens were included in several different collections including 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 ...
amber collection. The fossils were first studied by American entomologist
William Morton Wheeler
William Morton Wheeler (March 19, 1865 – April 19, 1937) was an American entomologist, myrmecologist and Harvard professor.
Biography Early life and education
William Morton Wheeler was born on March 19, 1865, to parents Julius Morton Wheeler ...
and described the genus plus two species in his 1915 paper ''The ants of the Baltic amber''.
Designated as the type species of the genus, ''P. tornquisti'' was described from a series of twenty two workers and two males placed into four different amber collections. In contrast, the species ''P. longicornis'' was described from a single male in the Klebs collection.
Since the genus and species descriptions by Wheeler, another species has been described from fossils found in Russia.
The third species was described from compression fossils preserved in
diatomite
Diatomaceous earth (), diatomite (), or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 μm to le ...
deposits of the Bol’shaya Svetlovodnaya site. Located in the
Pozharsky District
Pozharsky District (russian: Пожа́рский райо́н) is an administrativeLaw #161-KZ and municipalLaw #191-KZ district (raion), one of the twenty-two in Primorsky Krai, Russia. It is located in the northern and northwestern parts of t ...
, on the Pacific Coast of Russia, the fossil bearing rocks preserve possibly
Priabonian
The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage of t ...
plants and animals which lived in a small lake near a volcano. The site has been attributed to either the
Maksimovka or
Salibez Formations and compared to the
Bembridge Marls and
Florissant Formation
The Florissant Formation is a sedimentary geologic formation outcropping around Florissant, Teller County, Colorado. The formation is noted for the abundant and exceptionally preserved insect and plant fossils that are found in the mudstones and ...
, both of which are Priabonian in age.
Description
![Paraneuretus tornquisti GZG-BST04674 whole](https://upload.wikimedia.org/wikipedia/commons/6/6c/Paraneuretus_tornquisti_GZG-BST04674_whole.jpg)
The genus is separated from other members of Aneuretinae, notably ''
Aneuretus
The Sri Lankan relict ant (''Aneuretus simoni'') is a species of ant placed in a tribe of its own within the family Formicidae. The genus is monotypic, with the only species endemic to Sri Lanka, where it is known from just a few locations. It i ...
'' and ''
Protaneuretus'' based on several characters. The workers are longer and more slender than those of the other genera, and they have an elongated, narrow head capsule. In all three species, the gaster is smooth, showing no contrition between the first and second segments, and the petioles are node shaped with a
peduncle
''P. dubovikoffi''
''P. dubovikoffi'' was described from a single worker and a single gyne, both deposited in the A. A. Borissiak Paleontological Institute collections, part of the Russian Academy of Sciences. The worker is preserved as a partial profile impression, missing portions of the legs and antennae. The eyes are placed a little past the midpoint of the head capsule towards back, and have an oval shape. The upper side of the
pronotum
The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on ea ...
has a rounded profile appearance, as does the pronotum, and a mesopropodial constriction is present.
the petiole is a rounded node in shape and a short stalk attachment connects it to the propodium. The gyne is notably larger than the worker, at approximately long, and has a head that is wider than long when the mandibles are excluded. Also unlike the worker, the eyes are placed at the midpoint of the head, though they are small as the workers are. There are a number of denticles along the chewing margin on the large triangle shaped mandibles. While the scape extends beyond the back of the head, its total length is less than that of the head.
''P. longicornis''
Described from a single male in the private collection of Professor Richard Klebs of Königsberg University. It is smaller than the males of ''P. tornquisti'' but the antennae are longer, being nearly the same length as the body. The eyes ''P. longicornis'' are very convex and large with an almost totally circular outline. The petiole node has a longer base than in ''P. tornquisti'' while the gaster is shorter and the genitalia are not visible due to retraction into the gaster tip.
''P. tornquisti''
Workers of ''P. tornquisti'' range between long, with shiny black to red
coloration and fine punctation on the whole exoskeleton. The heads have sparse hairs across the mandibles,
clypeus and palpi, in addition to hairs sparsely scattered on the gaster. The antennae have scapes longer than the head capsule, with a third of the length past the rear edge of the head. All of the twelve antennae segments are elongate, each being at least twice as long as wide. The workers have a distinctly narrow thorax and bulging egg-shaped propodium. The node of the petiole is narrow and nearly double in length than it is wide, the node has a concave front edge and points rearward slowly. The males are similar in length to the larger workers, being about long. The thirteen segmented antennae are long, and reach to the second segment of the gaster. The petiole has the same proportions and profile shape as that of the workers. The gaster is narrow and long, with a slight widening from front to back and the genitalia have long and narrow stipites.
References
External links
*
*
{{Taxonbar, from=Q14450324
Insects of Asia
Eocene insects
Fossil ant taxa
Fossil taxa described in 1915
Fossil taxa described in 2015
Prehistoric insects of Europe
†Paraneuretus
Baltic amber