''Maatidesmus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Chelodesmidae known from a fossil found in North America. There is one described species in the genus, ''Maatidesmus paachtun'', one of three millipedes described from

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 ...

History and classification

''Maatidesmus paachtun'' was described from a solitary fossil, which is preserved as 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. At the time of description, the amber specimen was housed in the fossil collection of the Instituto Nacional de Antropología e Historia in

San Cristóbal de las Casas San Cristóbal de las Casas (), also known by its native Tzotzil name, Jovel (), is a town and municipality located in the Central Highlands region of the Mexican state of Chiapas. It was the capital of the state until 1892, and is still cons ...

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 ...

. 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 very complete adult female recovered from the La Guadalupe Quarry. Mexican amber is recovered from fossil bearing rocks in the

region of Chiapas, Mexico. The amber dates from between 23 million years old at the oldest and 15 million years at the youngest. The La Guadalupe Quarry site is an outcrop of amber-bearing strata belonging to the Mazantic shale. The deposits preserve a transitional river or stream environments near the coast and preserves fossils of a mangrove forest ecosystem. The holotype was first studied by a team of researchers headed by Francisco Riquelme of the Universidad Autónoma del Estado de Morelos with their 2014

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 genus and species being 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 '' PLOS ONE''. The genus name is a derived from a combination of the

Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken ...

word ''maat'' for "amber" and "idesmus", which is used frequently as a genus suffix in the family Chelodesmidae. The specific epithet ''paachtun'' was coined from a combination of the Mayan words ''paach'' meaning "back" and ''tun'' meaning "stone", a reference to the distinct sculpturing and lobing on the collum and lobe-bearing

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

s. ''M. paachtun'' is one of three millipede species described from Mexican amber, the others being '' Anbarrhacus adamantis'' and ''

Parastemmiulus elektron ''Parastemmiulus'' is an extinct genus of millipede in the family Stemmiulidae known from a fossil found in Mexico. There is one described species in the genus, ''Parastemmiulus elektron''. The species is one of three millipedes described fr ...

'', while a number of other species have been described from the similarly aged

Dominican amber Dominican amber is amber from the Dominican Republic derived from resin of the extinct tree '' Hymenaea protera''. Dominican amber differentiates itself from Baltic amber by being nearly always transparent, and it has a higher number of fossil inc ...

Description

Plos One e105877 Figure 3-A Maatidesmus paachtun

The ''M. paachtun'' female is mostly a creamy white in coloration with "splattering"s of nut-brown, though the specimen shows areas of recrystallization where the cuticle and amber reacted forming possible calcium carbonates. The total body length is and has a total of 19 body segments plus head. The head is a little wider than the next body segment, called the collum. The antennae have a total of seven

antennomeres Antennae ( antenna), sometimes referred to as "feelers", are paired appendages used for Sensory system, sensing in arthropods. Antennae are connected to the first one or two Segmentation (biology), segments of the arthropod head. They vary widel ...

that vary in length. The longest segments are antennomeres 2 and 6, while the shortest are antennomeres 1 and 7. The tops of the collum and body segments 2 to 5 are heavily lobed with three rows of lobes on each segment. The large lobes change to more scattered small lobes on segments 6 and 7. The segments gradually get wider from the head to segment 16 after which the segments start to narrow progressively to segment 19.

References

External links

* * {{Taxonbar, from=Q21682639 † Fossil taxa described in 2014 Millipedes of North America Miocene arthropods Mexican amber Millipede genera Prehistoric myriapod genera