''Liometopum imhoffii'' 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 ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of ants in the dolichoderine genus ''

Liometopum ''Liometopum'' is a genus of ants that belongs to the subfamily Dolichoderinae, found in North America, Europe and Asia. Caterpillars of certain butterfly species have a symbiotic relationship with ''Liometopum'' ants. They produce secretions t ...

''. The species was described from a number of Early Miocene

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s found in what is now

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

History and classification

The original group of fossils that the type species, and three other species, were described from are preserved as compression fossils in sedimentary rock from the

Radoboj Radoboj is a village and municipality in Krapina-Zagorje County in Croatia. In the 2011 census, the total population was 3,387, in the following settlements: * Bregi Radobojski, population 445 * Gorjani Sutinski, population 145 * Gornja Šemn ...

area of what is now Croatia. The deposits are the result of sedimentation in an inland sea basin, possibly a shallow lagoon environment, during the

Burdigalian The Burdigalian is, in the geologic timescale, an age (geology), age or stage (stratigraphy), stage in the early Miocene. It spans the time between 20.43 ± 0.05 annum, Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian (sta ...

of the Early Miocene. Along with ''L. imhoffii'' a diverse assemblage of several hundred species of insects have been preserved in the sediments, along with fish and algae. The fossil impressions are preserved in

micrite Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to four μm formed by the recrystallization of lime mud. Flügel, Erik, ''Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,'' Springe ...

limestones, resulting in low quality preservation of fine details. The insect fossils were first studied by

Oswald Heer Oswald Heer (or Oswald von Heer) (31 August 1809 – 27 September 1883), Swiss geologist and naturalist, was born at Niederuzwil in Canton of St. Gallen and died in Lausanne. Biography Oswald Heer was educated as a clergyman at Halle and ...

, then a professor with the University of Zürich, who placed the fossils in four new ant species in two different genera, "''Formica imhoffii''", "''Formica schmidtii''", "''Ponera fuliginosa radobojana''", and "''Ponera affinis''". Based on the petiole structure and wing venation, Heer subsequently moved the four species to the new genus "''Poneropsis''" in 1867 as "''Poneropsis affinis''", "''P. fuliginosa''", "''P. imhoffii''", and "''P. schmidtii''". He also described three new species, "''P. livida''", "''P. lugubris''", and "''P. morio''". In the same year, entomologist Gustav Mayr of Vienna examined a number of fossils from Radoboj, some being the type specimens, others being identified by Heer but not types. Later in 1907

Anton Handlirsch Anton Handlirsch or Anton Peter Josef Handlirsch (20 January 1865, Vienna – 28 August 1935, Vienna) was an Austrian entomologist. He worked on many groups including Hemiptera, Hymenoptera and Neuroptera. His most significant work was in the stu ...

revisited the work of Mayr and Heer in a monograph of fossil ants. In 2014 a series of 21 specimens, many of the type specimens plus additional fossils, were reexamined and redescribed by paleoentomologists Gennady Dlussky and Tatyana Putyatina. Mayr examined eight of the Radoboj specimens belonging to the species "''F. imhoffi''" and "''F. schmidtii''", noting the similarity between the males of the two species, and that they likely belonged to the genus ''Liometopum''. Following on Mayr's suggestion Handlirsch formally synonymized the two species, giving "''P. imhoffii''" seniority over "''P. schmidtii''", and moved the species to ''Liometopum''. Heer based the species "''P. fuliginosa''" on fossils from both Radoboj and Öhningen, Germany. When Mayr examined several of the specimens, he interpreted them to show a two segmented petiole, and moved both "''P. fuliginosa''" and "''P. livida''" to the genus ''

Aphaenogaster ''Aphaenogaster'' is a genus of myrmicine ants. About 200 species have been described, including 18 fossil species. They occur worldwide except in South America south of Colombia, sub-Saharan Africa, and Antarctica. They are often confused w ...

''. In contrast, Heer in 1867 moved the two species to his new genus "''Poneropsis''", a move that was followed by

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 ...

in 1911 when he designated "''P. fuliginosa''" the type species of the genus. The single type specimen of "''P. affinis''" was preserved with a distorted head and wing proportions, from which Heer differentiated the species from "''P. fuliginosa''". Neither Mayr or Handlirsch were able to study the fossil, so they did not comment on the species status. However Dlussky and Putyatina concluded that the specimen did not differ from "''P. fuliginosa''" when the distortion of the fossil was accounted for, and included it as a junior synonym of ''L. imhoffii''. Following the research of Mayr and Handlirsch, Dlussky and Putyatina agreed with the placement in ''Liometopum''. Based on examination of one of the "''P. fuliginosa''" type queens, and on Heer's illustrations, they also concluded "''P. fuliginosa''" was a junior synonym of ''L. imhoffii''. Of all the species named, Dlussky and Putyatina were not able to examine the type specimens for "''F. livida''" and "''P. morio''", only other specimens looked at and identified by Heer. In both species, the examined fossils do not match the descriptions published by Heer, and either belong to other species, or are not well enough preserved to identify at all. Based on Heer's 1867 descriptions and illustrations Dlussky and Putyatina concluded that both are synonyms of ''Liometopum imhoffii''. Heer named ''L. imhoffii'' for his friend Ludwig Imhoff of Basel, Switzerland.

Description

The queens of ''L. imhoffi'' range between in length with rectangular heads that are slightly wider than long. The sides of the head are convex in outline, while the rear margin curves inwards near the middle. The

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 ...

is wider than the maximum width of the head and thick in construction, while the fore section of the mesonotum is large and the legs are robust and short. The petiole has a wide scale on the node and connects to an oval gaster. The males are smaller than the queens, ranging between in length and having a much smaller head. The legs are longer and thinner than those of the queen, while the mesosoma is wider than the head, as in the queens. The males have a petiole that is low and triangular in outline, the node being only 1.5 times as high as long. Unlike the oval gaster of the queens the males have a more elongated egg shaped gaster.

References

External links

{{Taxonbar, from=Q18926201 † Miocene insects Prehistoric insects of Europe Fossil taxa described in 1849 Fossil ant taxa