Polydesmida
Guides
Akamptogonus
A genus of flat-backed millipedes in the family Paradoxosomatidae, containing approximately 11 described species. The genus was established by Attems in 1914. Species occur across parts of Australia, New Guinea, and surrounding regions. As members of the Polydesmida, they possess a flattened body form with lateral extensions (paranota) on each body segment.
Akamptogonus novarae
Akamptogonus novarae is a flat-backed millipede in the family Paradoxosomatidae, first described from the Austro-Hungarian Novara expedition in 1869. The species exhibits a notably broad geographic distribution spanning Australia, North America, and Oceania, which is unusual for a millipede and suggests possible human-mediated dispersal. It belongs to the order Polydesmida, the largest order of millipedes, characterized by their flattened body form.
Apheloria montana
mountain cherry millipede
Apheloria montana is a large flat-backed millipede in the family Xystodesmidae, native to the southern Appalachian Mountains of eastern Tennessee and western North Carolina. It serves as the type species for the genus Apheloria. The species produces hydrogen cyanide and benzaldehyde as chemical defenses, which emit a characteristic cherry or almond odor. Its bright yellow or orange spots function as aposematic coloration warning predators of its toxicity.
Boraria deturkiana
Boraria deturkiana is a species of flat-backed millipede in the family Xystodesmidaedescribed by Causey in 1942. The genus Boraria is part of the tribe Rhysodesmini within the subfamily Rhysodesminae. Like other members of the order Polydesmida, this species possesses laterally expanded dorsal segments (paranota) that give it a flattened appearance. The taxonomic status of this species has been debated, with some sources treating it as a synonym of Howellaria deturkiana.
Boraria infesta
Boraria infesta is a species of flat-backed millipede in the family Xystodesmidae, native to southeastern North America. It belongs to a group of polydesmidan millipedes that produce hydrogen cyanide as a chemical defense and display aposematic coloration warning predators of their toxicity. The species is part of a genus closely related to other cyanide-producing millipedes including Apheloria and Pleuroloma.
Boraria stricta
Boraria stricta is a flat-backed millipede in the family Xystodesmidae, characterized by its dorsoventrally flattened body form typical of the order Polydesmida. The species is native to North America and belongs to a genus known for aposematic coloration warning of chemical defenses. Like other xystodesmid millipedes, it possesses paranota—lateral extensions of body segments that contribute to its flattened appearance.
Cherokia georgiana
Georgia Flat-backed Millipede, Wrinkled Flat-backed Millipede
Cherokia georgiana is a monospecific millipede genus in the family Xystodesmidae, representing the sole species in genus Cherokia. Molecular phylogenetic analysis of seven gene loci supports recognition of a single highly variable species, with three formerly recognized subspecies (C. g. ducilla, C. g. latassa) now synonymized. The species exhibits extensive morphological variation in coloration, body size, and paranota shape that correlates with geography and elevation rather than phylogenetic relationships. It is sister to the genus Pleuroloma.
Dicellarius lamprus
Dicellarius lamprus is a species of flat-backed millipede in the family Xystodesmidae. It was described by Chamberlin in 1918 and is found in North America. The species belongs to a genus of xystodesmid millipedes characterized by their flattened body form.
Gyalostethus
Gyalostethus is a genus of flat-backed millipedes in the family Xystodesmidae, described by Hoffman in 1965. It belongs to the tribe Rhysodesmini and is part of the diverse order Polydesmida, which contains many North American millipede species. The genus is poorly documented in scientific literature, with limited species-level information available.
Kepolydesmus
Kepolydesmus is a genus of flat-backed millipedes in the family Nearctodesmidae. The genus was established by Chamberlin in 1910 and contains at least four described species. These millipedes belong to the order Polydesmida, which is characterized by a flattened body form. The genus has been documented through iNaturalist observations and is recognized in major taxonomic databases including GBIF and NCBI.
Kepolydesmus anderisus
Kepolydesmus anderisus is a small, flat-backed millipede species first described by Chamberlin in 1910. It belongs to the family Nearctodesmidae, a group of polydesmidan millipedes characterized by relatively simple gonopod structures and North American distribution. The species was originally described as Polydesmus anderisus before being transferred to Kepolydesmus. Like other members of its family, it likely inhabits moist forest floor habitats where it contributes to decomposition processes.
Montaphe elrodi
Montaphe elrodi is a species of flat-backed millipede in the family Xystodesmidae, first described by Chamberlin in 1913 under the basionym Leptodesmus elrodi. It belongs to the order Polydesmida, a diverse group of millipedes characterized by their flattened body form. The species is known from North America, though specific details about its biology remain limited in published literature.
Myrmecodesmus
A genus of small-bodied polydesmid millipedes in the family Pyrgodesmidae. Established by Silvestri in 1910 with a myrmecophilous species from central Veracruz, Mexico. The genus has undergone extensive taxonomic revision, with numerous genera synonymized under it by Shear (1977). Currently includes at least 28 species distributed from Mexico through South America and into the Caribbean.
Nannaria
Twisted-Claw Millipedes
Nannaria is a genus of small-bodied millipedes in the family Xystodesmidae, commonly known as twisted-claw millipedes. First described by Ralph Chamberlin in 1918, it is now the largest genus in its family with 78 described species following major revisions in 2022. The genus comprises two monophyletic species groups: the widespread minor group found throughout eastern North America, and the wilsoni group restricted to the Appalachian Mountains. Unlike many colorful, flat-backed xystodesmids, Nannaria species are cryptic in appearance and exhibit subterranean behavior that makes them difficult to collect.
Nannaria hardeni
Curt Harden's Twisted-Claw Millipede
Nannaria hardeni is a species of twisted-claw millipede described in 2021 from the Appalachian Mountains of the eastern United States. It belongs to the genus Nannaria, a group of forest-dwelling millipedes characterized by males having small, twisted and flattened claws on their anterior legs. The species was named in honor of Curt Harden, a millipede researcher who contributed significantly to the study of Appalachian xystodesmid millipedes. Like other members of its genus, N. hardeni plays a role as a decomposer in forest ecosystems.
Nannaria terricola
Loam-dwelling Twisted-Claw
Nannaria terricola is a flat-backed millipede in the family Xystodesmida, characterized by its loam-dwelling habits and the distinctive twisted, flattened claws on the anterior legs of males. The species is found in the Great Lakes region of the United States. Like other members of the genus Nannaria, it plays a role as a decomposer in forest ecosystems. The species was originally described as Fontaria terricola by Williams & Hefner in 1928 before being transferred to Nannaria.
Nannariini
Nannariini is a tribe of flat-backed millipedes within the family Xystodesmidae, subfamily Rhysodesminae. The tribe was established by Hoffman in 1964 and comprises several genera of small to medium-sized polydesmidan millipedes found primarily in North America. Members of this tribe are characterized by specific gonopodal modifications that distinguish them from related tribes within Rhysodesminae.
Nearctodesmus
Nearctodesmus is a genus of small millipedes in the order Polydesmida, family Nearctodesmidae. These millipedes are characterized by their flattened bodies and reduced segmentation. The genus was established by Silvestri in 1910 and is primarily distributed in the Nearctic region. Members of this genus are part of the diverse soil fauna and contribute to decomposition processes in forest ecosystems.
Orthomorpha
Orthomorpha is a genus of flat-backed millipedes in the family Paradoxosomatidae, comprising approximately 50 species native to Southeast Asia. Adults possess 20 body segments and range from 15–50 mm in length, with prominent lateral keels (paranota) that often display bright coloration. The genus includes both endemic tropical species and at least one species, O. coarctata, that has been widely introduced by humans to tropical regions worldwide. Several species are commonly found in human-modified environments including greenhouses and heated buildings.
Oxidus
greenhouse millipedes
Oxidus is a genus of flat-backed millipedes in the family Paradoxosomatidae, containing approximately nine described species, though recent revision recognizes five valid species with one species inquirenda. The genus is characterized by a cosmopolitan member, Oxidus gracilis (the greenhouse millipede), which has achieved global distribution in temperate and sub-tropical regions, while other species exhibit restricted endemic ranges. Phylogenetic analysis based on mitochondrial COI and 16S rRNA genes confirms Oxidus as monophyletic and closely related to the genus Tylopus. Species within the genus are distinguished primarily by gonopod morphology, coloration, and body size.
Oxidus gracilis
Greenhouse Millipede, Hothouse Millipede, Short-flange Millipede, Garden Millipede
Oxidus gracilis is a widely introduced millipede species in the family Paradoxosomatidae, native to Asia but established globally including North America, South America, Europe, and Pacific islands. It is commonly known as the greenhouse millipede due to its frequent occurrence in artificial environments. The species exhibits innate congregating behavior toward food resources and demonstrates generalist habitat use with no strong association to specific soil moisture, leaf litter, or rock cover conditions. It has been studied as a potential bioindicator for environmental pollution due to characteristic internal element composition.
Pachydesmus crassicutis
Pachydesmus crassicutis is a species of flat-backed millipede in the family Xystodesmidae, first described by Wood in 1864. The species is recognized as having eight subspecies, indicating considerable geographic variation across its range. It belongs to the order Polydesmida, the largest order of millipedes, characterized by their flattened body form. The species is part of a genus containing multiple species distributed in North America.
Paradoxosomatidae
flat-backed millipedes
Paradoxosomatidae is the largest family of flat-backed millipedes, containing nearly 200 genera and approximately 975 species as of 2013. It is the sole family in the suborder Paradoxosomatidea. Members are distinguished by dorsal grooves on most body segments and a dumb-bell shaped gonopod aperture in males. The family includes notable groups such as the dragon millipedes of Southeast Asia and the widely introduced greenhouse millipede Oxidus gracilis.
Pseudopolydesmus collinus
Rolling Hills Flat-back
Pseudopolydesmus collinus is a flat-backed millipede in the family Polydesmidae, described by Hoffman in 1974. It belongs to the order Polydesmida, characterized by their dorsoventrally flattened bodies. The species is known from limited records in Virginia, United States. As with other members of its genus, it likely inhabits moist forest floor environments typical of polydesmid millipedes.
Rhysodesmus texicolens
Rhysodesmus texicolens is a flat-backed millipede in the family Xystodesmidae. First described by Chamberlin in 1938, it is currently treated as a synonym of Aporiaria texicolens in some taxonomic databases. The species has been documented in Texas and is part of a diverse genus of polydesmidan millipedes found in North America.
Scytonotus
Scytonotus is a genus of flat-backed millipedes in the family Polydesmidae, containing approximately 17 described species. The genus was established by C.L. Koch in 1847. Members of this genus are part of the diverse order Polydesmida, which includes millipedes with flattened bodies and lateral extensions of their dorsal plates (paranota). Species in this genus are poorly documented in scientific literature, with limited ecological and behavioral data available.
Semijulistus flavipes
Semijulistus flavipes is a flat-backed millipede in the family Xystodesmidae, order Polydesmida. The species was formerly classified under the genus Pleuroloma, and taxonomic revisions have placed it in Semijulistus. Like other xystodesmid millipedes, it produces hydrogen cyanide (HCN) as a chemical defense. The specific epithet "flavipes" refers to yellow leg coloration.
Sigmoria aequalis
Sigmoria aequalis is a species of flat-backed millipede in the family Xystodesmidae, described by Shelley in 1981. It belongs to the order Polydesmida, a large and diverse group of millipedes characterized by their flattened body form. The genus Sigmoria is part of the tribe Apheloriini within the subfamily Rhysodesminae, a predominantly North American lineage of xystodesmid millipedes.
Tidesmus
Tidesmus is a genus of small-bodied millipedes in the family Macrosternodesmidae, order Polydesmida. The genus was revised in 2007, with Phreatodesmus and Oodedesmus synonymized under it. It currently contains four valid species distributed in the southwestern United States and northwestern Mexico. The type species is T. episcopus Chamberlin, 1943.
Tidesmus episcopus
Tidesmus episcopus Chamberlin, 1943 is a small-bodied millipede and the type species of the genus Tidesmus (family Macrosternodesmidae). The species was originally described from western North America and is one of four recognized species in the genus. Phreatodesmus cooki Loomis, 1960 has been synonymized with this species. The family Macrosternodesmidae was redefined in a 2007 revision that clarified the generic placement of several western North American species.
Xystocheir dissecta taibona
Xystocheir dissecta taibona is a subspecies of flat-backed millipede in the family Xystodesmidae. It is a synonym of Xystocheir taibona and is known from California. Like other members of its genus, it produces cyanide as a chemical defense against predators. The subspecies is documented as prey for the specialized carabid beetle Promecognathus.
Xystodesmini
Xystodesmini is a tribe of flat-backed millipedes within the family Xystodesmidae, order Polydesmida. The tribe was established by Hoffman in 1978 and contains multiple genera of medium to large-sized millipedes found primarily in North America. Members are characterized by their flattened bodies with lateral extensions (paranota) and often display aposematic coloration. The tribe is well-represented in citizen science observations, with over 18,000 records on iNaturalist.