title: Two flat-backed polydesmidan millipedes from the Miocene Chiapas-amber Lagerstätte, Mexico.
abstract: Two species of fossil polydesmidan millipedes (Diplopoda: Polydesmida) embedded in amber are described from Miocene strata near Simojovel, in the Chiapas Highlands, Mexico. Maatidesmus paachtun gen. et sp. nov., placed into Chelodesmidae Cook, 1895, and Anbarrhacus adamantis gen. et sp. nov., assigned in the family Platyrhacidae Pocock, 1895. Morphological data from fossil specimens have been recovered using 3D X-ray micro-computed tomography and regular to infrared-reflected microscopy. Both fossil species are recognizable as new primarily but not exclusively, by collum margin modification and remarkable paranotal and metatergite dorsal sculpture.
authors.affiliation: Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México; Instituto de Física, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: Francisco
authors.initials: F
authors.lastname: Riquelme
authors.affiliation: Subcoordinación de Inventarios Bióticos, Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, Tlalpan, D.F., México.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernández-Patricio
authors.affiliation: Instituto de Física, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: Arnulfo
authors.initials: A
authors.lastname: Martínez-Dávalos
authors.affiliation: Instituto de Física, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rodríguez-Villafuerte
authors.affiliation: Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: Maira
authors.initials: M
authors.lastname: Montejo-Cruz
authors.affiliation: Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: Jesús
authors.initials: J
authors.lastname: Alvarado-Ortega
authors.affiliation: Instituto de Física, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F., México.
authors.forename: José L
authors.initials: JL
authors.lastname: Ruvalcaba-Sil
authors.affiliation: Museo del Ámbar Lilia Mijangos, San Cristóbal de las Casas, Chiapas, México.
authors.forename: Luis
authors.initials: L
authors.lastname: Zúñiga-Mijangos
mesh_terms: D018647:Amber; D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology* / Q000145:classification; D005580:Fossils; D008800:Mexico; D010802:Phylogeny; D013055:Spectrophotometry, Infrared; D055114:X-Ray Microtomography
chemical_list: D018647:Amber