''Mastotermes electromexicus'' 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 ...

termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blatto ...

in the family Mastotermitidae known from a group of

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 (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

fossils 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 ...

. ''M. electromexicus'' is the only species in the genus '' Mastotermes'' to have been described from fossils found in

Mexican amber Mexican amber, also known as Chiapas Amber is amber found in Mexico, created during the Early Miocene and middle Miocene epochs of the Cenozoic Era in southwestern North America. As with other ambers, a wide variety of taxa have been found as inc ...

and was the first member of the genus described from the New World. The only living species of ''Mastotermes'' is ''

Mastotermes darwiniensis ''Mastotermes darwiniensis'', common names giant northern termite and Darwin termite, is a termite species found only in northern Australia. It is the most primitive extant termite species. Evolutionary significance This species shows uncanny s ...

'' which is found in tropical regions of

Northern Australia The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26° and all of the Northern Territory. Those local government areas of Western Australia and Queensland that lie p ...

History and classification

''Mastotermes electromexicus'' is known from a series of fourteen fossil insects which are inclusions in transparent chunks of Mexican amber. The amber specimens, a

soldier A soldier is a person who is a member of an army. A soldier can be a conscripted or volunteer enlisted person, a non-commissioned officer, or an officer. Etymology The word ''soldier'' derives from the Middle English word , from Old French ...

, an imago and twelve nymphs are currently housed in the fossil collection of the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

Berkeley, California Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and E ...

. 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 sever ...

fossil is composed of a partial soldier caste individual. 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, Mexico. The amber dates from between 22.5 million years old, for the youngest sediments of the Balumtun Sandstone, 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 only the youngest that it might be. The holotype was first studied by entomologists Kumar Krishna of the American Museum of Natural History and Alfred Emerson of the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private university, private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park, Chicago, Hyde Park neighborhood. The University of Chic ...

. Krishna and Emerson's 1983

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

natural sciences Natural science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatab ...

journal ''

American Museum Novitates ''American Museum Novitates'' is a peer-reviewed academic journal published by the American Museum of Natural History. It was established in 1921. According to the ''Journal Citation Reports'', the journal has a 2013 impact factor The impact f ...

''. The specific epithet ''electromexicus'' was coined from 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 "ēlektron" meaning ''amber'' combined with Mexico as a reference to the nature of the preservation and the country of the type locality.

Description

The ''Mastotermes electromexicus'' soldier is known from only a portion of the head and mandible. The head is estimated to have been wide with long hairs on each side of the head below the antennae. The mandibles are gently curved inwards, in contrast to those of ''M. darwiniensis'' which are a more curved and having a hooked appearance. The imago is known from a partial head, thorax, and hind wings. The wide head of the imago is wider than seen in ''M. darwiniensis'' with smaller eyes and

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 ...

which do not touch the compound eyes. The nymphs are known from a series of partial fossils in thirteen pieces of amber and representing several different

instars An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

. The heads vary between , showing a larger range of size then those of ''M. darwiniensis''. The antennae have approximately twenty four segments, flagellomeres, and the legs host a number of bristles and several short spines.

References

{{Taxonbar, from=Q6785607 Termites Eocene insects of North America Oligocene insects Paleogene insects of North America Prehistoric insects of North America Mexican amber Fossil taxa described in 1983