Polydesmida is the largest order of millipedes, with more than 5,000 species, including all the millipedes reported to produce hydrogen cyanide (HCN). This order is also the most diverse of the millipede orders in terms of morphology. Millipedes in this order are found in all regions of the world other than Antarctica.
Xystodesmidae is a family of millipedes in the suborder Leptodesmidea within the order Polydesmida. The family Xystodesmidae was created by the American biologist Orator F. Cook in 1895 and named after the genus Xystodesmus. This family includes more than 390 known species distributed among 62 genera. Many species, however, remain undescribed: for example, it is estimated that the genus Nannaria contains over 200 species, but only 25 were described as of 2006. By 2022, 78 species in Nannaria have been described.
Motyxia is a genus of cyanide-producing millipedes that are endemic to the southern Sierra Nevada, Tehachapi, and Santa Monica mountain ranges of California. Motyxias are blind and produce the poison cyanide, like all members of the Polydesmida. All species have the ability to glow brightly: some of the few known instances of bioluminescence in millipedes.
Xystocheir is a genus of millipedes in the family Xystodesmidae. The genus is endemic to California in the United States, where it is distributed in the Coast Ranges and the Sierra Nevada.
Apheloria is a genus of flat-backed millipedes in the family Xystodesmidae, occurring in the central and southeastern United States, and ranging as far north as southern Quebec, Canada. They are aposematically colored in black and contrasting reds and yellows, and some species in the Appalachian Mountains resemble species of Brachoria where they co-occur, a phenomenon known as Müllerian mimicry.
Brachoria dentata, the Pennington Gap mimic millipede, is an Appalachian mimic millipede in the Xystodesmidae family.
Pseudopolydesmus is a genus of flat-backed millipedes in the family Polydesmidae.
Pleuroloma flavipes, commonly known as the traveling cherry millipede, is a species of flat-backed millipede in the family Xystodesmidae. It has the widest distribution of any species of xystodesmid millipede and is found in eastern North America from southeastern North Dakota, eastward to Connecticut, and southward to North Carolina, northern Louisiana, and southern Texas. Pleuroloma flavipes millipedes are occasionally observed in large aggregations of individuals where they appear to move en masse in a certain direction, hence the common name "wandering cherry millipede". In a report from 1950, an aggregation of about 6,000 individuals were encountered on a single bridge at McCormick's Creek State Park, Indiana. The species is extremely variable in coloration, and converges in appearance with several species of Apheloria and Brachoria as a result of mimicry.
The genus Nannaria, commonly known as twisted-claw millipedes, is a genus of millipedes in the family Xystodesmidae first described by Ralph Chamberlin in 1918. In 2022, entomologists Derek Hennen, Jackson Means and Paul Marek discovered and described 17 new species, which expanded the size of Nannaria to 78, making it the largest genus of Xystodesmidae.
Boraria is a genus of flat-backed millipedes in the family Xystodesmidae. There are about seven described species in Boraria.
Desmonus is a genus of flat-backed millipedes in the family Sphaeriodesmidae. There are about 10 described species in Desmonus.
Sigmoria is a genus of flat-backed millipedes in the family Xystodesmidae. There are more than 60 described species in Sigmoria, found in the eastern United States.
Cherokia Chamberlin, 1949 is a genus consisting of a single species, Cherokia georgiana. Commonly known as the wrinkled flat-backed millipede, this species belongs to the order Polydesmida and the family Xystodesmidae. It inhabits forests in the southeastern United States, particularly those with hemlock, maple, tulip poplar, rhododendron, cedar, and spruce-fir trees.
Cambala is a genus of millipedes in the family Cambalidae. There are about 18 described species in Cambala.
Rudiloria is a genus of millipedes in the family Xystodesmidae, found in eastern North America.
Nannaria swiftae, also known as the Swift twisted-claw millipede or Taylor Swift's millipede, is a species of millipede in the family Xystodesmidae. It is found only in the Appalachian mountains of the U.S. state of Tennessee. It was discovered and described in 2022 by entomologists Derek Hennen, Jackson Means and Paul Marek, who expanded the genus Nannaria to 78 species. They named the species in honor of American singer-songwriter Taylor Swift.
Tubaphe is a genus of millipede in the family Xystodesmidae with a single described species, Tubaphe levii. The genus was erected by Nell B. Causey in 1954.
Rhysodesminae is a subfamily of millipedes belonging to the family Xystodesmidae within the order Polydesmida.
Apheloriini is a tribe of millipedes within the subfamily Rhysodesminae.
