''Aphaenogaster avita'' is an extinct

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 ...

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 ...

in the subfamily Myrmicinae known from a solitary early to middle Miocene fossil found in Japan. At the time of description ''A. praerelicta'' was one of twelve '' Aphaenogaster'' species to have been described from fossils and the only fossil species from Japan.

History and classification

''Aphaenogaster avita'' is known from a solitary fossil insect which is a compression-impression fossil preserved in a layer of soft

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 ...

. Along with several other insect fossils, the ''A. avita'' specimen was collected in 1969 from layers of the early to middle Miocene Chojabaru Formation. The formation is composed of diatomites, sandstones and mudstones with the insects recovered from the upper and middle sections. The formation outcrops in a small area on Cape Chojabaru on the eastern side of

Iki Island , or the , is an archipelago in the Tsushima Strait, which is administered as the city of Iki in Nagasaki Prefecture, Japan. The islands have a total area of with a total population of 28,008. Only four (4) of the twenty-three (23) named island ...

, and the flora of the formation is notably similar to that of Daijima flora, which is noted to be Middle Miocene in age. The fossil ant was first studied by paleoentomologist Ienori Fujiyama of the National Museum of Nature and Science in

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...

. Fujiyama's 1970

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

of the new species was published in the Japanese journal ''Memoirs of the Natural Science Museum, Tokyo''. The

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

for the specific epithet ''avita'' was not given with the type description. When first described the species was placed by Fujiyama into the ''Aphaenogaster'' subgenus "''Deromyrma''", however in the time since the type description, "''Deromyrma''" has been subsumed into ''Aphaenogaster'' as a junior synonym and is no longer in use.

Description

The ''Aphaenogaster avita'' specimen is a partially preserved queen caste adult which was fossilized with its underside facing upwards and the body turned slightly sideways. The specimen has wings attached, a poorly preserved head and is missing its abdomen, making gender determination hard. The head has an estimated length of and the thorax is estimated at with distinct longitudinal striations on it. The preserved

forewing Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindwi ...

is long and has a maximum width of . The wing venation shows a narrow costal cell and a thin stigma. The wing shows a reduced cubital vein, with a notable bend, and forming an elongated cubital cell with the median vein.

References

{{Taxonbar, from=Q14445659 avita Miocene insects Fossil ant taxa Ants of Japan Fossils of Japan Fossil taxa described in 1970