''Schwenckfeldina archoica'' 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 dark winged fungus gnat in the family

Sciaridae The Sciaridae are a family of flies, commonly known as dark-winged fungus gnats. Commonly found in moist environments, they are known to be a pest of mushroom farms and are commonly found in household plant pots. This is one of the least studie ...

known from a solitary

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

fossil found in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. ''S. archoica'' is the only species in the genus '' Schwenckfeldina'' to have been described from fossils found in Mexican

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...

History and classification

''Schwenckfeldina archoica'' is known from a single fossil, an

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 ...

in a transparent chunk of Mexican amber. The amber specimen, number ''SMNS Mx 367'', is currently housed in the fossil collection of the

State Museum of Natural History Stuttgart The State Museum of Natural History Stuttgart (german: Staatliches Museum für Naturkunde Stuttgart), abbreviated SMNS, is one of the two state of Baden-Württemberg's natural history museums. Together with the State Museum of Natural History ...

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

, Germany. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

fossil is composed of a fully complete adult male. Mexican amber is recovered from fossil-bearing rocks in the

Simojovel Simojovel is one of the 119 municipalities of Chiapas, in southern Mexico. As of 2010, the municipality had a total population of 40,297, up from 31,615 as of 2005. It covers an area of 446.99 km2. The municipality had 145 localities, the ...

region of

Chiapas Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...

, Mexico. The amber dates from between 22.5 million years old, for the youngest sediments of the

Balumtun Sandstone The Balumtun Sandstone is a geologic formation in Chiapas, Mexico. The formation is up to 760 metres thick, and consists of gray sandstone, that were deposited during the Upper Aquitanian stage of the Early Miocene. See also * List of fossili ...

, and 26 million years old

La Quinta Formation The La Quinta Formation is a Jurassic geologic formation which crops out in the Cordillera de Mérida and Serranía del Perijá of western Venezuela and northeastern Colombia. The formation is also present in the subsurface of the Cesar-Rancher ...

. This age range straddles the boundary between the

and

and is complicated by both formations being secondary deposits for the amber; the age range is therefore only the youngest that it might be. The holotype was first studied by entomologists Mónica M. Solórzano Kraemer of the Institut für Paläontologie, part of the

University of Bonn The Rhenish Friedrich Wilhelm University of Bonn (german: Rheinische Friedrich-Wilhelms-Universität Bonn) is a public research university located in Bonn, North Rhine-Westphalia, Germany. It was founded in its present form as the ( en, Rhine U ...

, and Werner Mohrig of

Poseritz Poseritz is a municipality in the Vorpommern-Rügen district, in Mecklenburg-Vorpommern Mecklenburg-Vorpommern (MV; ; nds, Mäkelborg-Vörpommern), also known by its anglicized name Mecklenburg–Western Pomerania, is a state in the north-ea ...

, Germany. To better see the fossil, the amber was cut into a thick piece and polished with leather for clarity. Solórzano Kraemer and Mohrig's 2012

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 species was published in the Palaeoentomology journal '' Alavesia''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''archoica'' was coined after the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word "archaic" as a reference to the great number of features shared between modern species and the fossil.

Description

The ''Schwenckfeldina archoica'' male is small, approximately long, and has a body coloration that is mostly brown. There are a total of sixteen brown

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 ...

s in each antenna, with all the flagellomeres wider than they are long, and all covered with a dense grouping of

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

e. The fore wings are pale and the

halteres ''Halteres'' (; singular ''halter'' or ''haltere'') (from grc, ἁλτῆρες, weights held in the hands to give an impetus in leaping) are a pair of small club-shaped organs on the body of two orders of flying insects that provide infor ...

are short and brown. The species is distinguishable by the structure of the male genitalia, the gonocoxites and gonostyli. The inner sides of the gonocoxites are covered in numerous long bristles, while the gonostyli have an overall broad rounded shape and are brown in color. The outer sides of the gonostyli have long bristles that progress to coat the upper third of the inner side. Three large spines are present in the middle of the inner surface, with the uppermost spine shorter the other two.

References

{{Taxonbar, from=Q7433268 Sciaridae Oligocene insects Miocene insects Fossil taxa described in 2007 Diptera of North America Prehistoric insects of North America Mexican amber