Flat-backed-millipede
Guides
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 virginiensis corrugata
Aromatic Cherry Millipede
Apheloria virginiensis corrugata is a subspecies of flat-backed millipede in the family Xystodesmidae, commonly known as the Aromatic Cherry Millipede. Like other members of the genus Apheloria, it produces hydrogen cyanide (HCN) as a chemical defense and displays bright aposematic coloration warning predators of its toxicity. The species exhibits the characteristic flattened body shape of Polydesmida, with lateral expansions of the dorsal segments called paranota. It belongs to a group of xystodesmid millipedes that share warning coloration patterns across related genera including Apheloria, Boraria, and Cherokia.
Apheloriini
cherry millipedes
Apheloriini is a tribe of large, colorful flat-backed millipedes endemic to the temperate forests of eastern North America. All species produce hydrogen cyanide as a chemical defense, which generates a characteristic cherry or almond odor from benzaldehyde byproducts. Members display bright aposematic coloration warning predators of their toxicity. The tribe includes seven genera, with greatest diversity concentrated in the southern Appalachian Mountains. Species in this tribe participate in Müllerian mimicry rings, resulting in extreme intraspecific variation in color patterns.
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.
Brachycybe producta
Brachycybe producta is a species of millipede in the family Andrognathidaefound in North America. It belongs to the order Platydesmida, a group of small, flattened millipedes commonly known as flat-backed millipedes. The species was described by Loomis in 1936. It is part of the Colobognatha, a clade of millipedes characterized by reduced mouthparts.
Chonaphini
Chonaphini is a tribe of flat-backed millipedes (Polydesmida) within the family Xystodesmidae, established by Verhoeff in 1941. The tribe comprises approximately 6 genera and 19 described species distributed across western North America. Members exhibit the characteristic dorsoventrally flattened body form typical of xystodesmid millipedes.
Chondromorpha xanthotricha
Chondromorpha xanthotricha is a millipede in the family Paradoxosomatidae. Native to South India and Sri Lanka, it has become a widespread introduced species across tropical and subtropical regions through human-mediated transport. Adults measure 20–26 mm and exhibit notably rapid movement compared to many millipedes. Two subspecies are recognized: C. x. hamuligerus and C. x. hirsutus.
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.
Euryuridae
Euryuridae is a family of flat-backed millipedes in the order Polydesmida. The family includes at least four genera and approximately 14 described species. Members are endemic to the Nearctic region. One well-studied species, Euryurus leachii, has been used to investigate thermal tolerance in detritivorous arthropods.
Euryurus evides
Euryurus evides is a North American millipede species in the family Xystodesmidae, order Polydesmida. It belongs to a genus of flat-backed millipedes characterized by their broad, flattened bodies and distinctive color patterns. The species was described by Bollman in 1887 and is part of the tribe Euryurini within the subfamily Rhysodesminae. It is among the more frequently observed millipedes in its range, with substantial occurrence records on community science platforms.
Furcillaria
Furcillaria is a genus of flat-backed millipedes established by Shelley in 1981 within the family Xystodesmidae. It originally comprised four species from the eastern United States: Furcillaria aequalis, F. convoluta, F. laminata, and F. thrinax. In 2021, taxonomic authorities reevaluated the genus and deemed it a junior synonym of Sigmoria, a decision now reflected in major databases such as the Catalogue of Life. Some sources, including GBIF and NCBI, continue to list Furcillaria as accepted, reflecting ongoing taxonomic debate or lag in database updates. The genus belongs to the tribe Apheloriini, a group of xystodesmid millipedes characterized by complex gonopod morphology.
Harpogonopus
Harpogonopus is a genus of millipedes in the family Nearctodesmidae, order Polydesmida. The genus was established by Loomis in 1960. Members of this genus belong to the flat-backed millipede group, characterized by lateral extensions (paranota) on most body segments. The genus occurs in the Nearctic region.
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.
Macrosternodesmidae
Macrosternodesmidae is a family of flat-backed millipedes in the order Polydesmida, primarily distributed in western North America with some European representatives. The family contains approximately 9 genera and 16 described species, though taxonomic status remains disputed—some authorities treat it as a junior synonym of Trichopolydesmidae, while others recognize it as valid with two subfamilies: Macrosternodesminae and Nearctodesminae. Many species are troglobionts restricted to cave systems.
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.
Nannaria ohionis
Ohio Twisted-Claw
Nannaria ohionis is a species of flat-backed millipede in the family Xystodesmidae, first described by Loomis & Hoffman in 1948. It belongs to the genus Nannaria, commonly known as twisted-claw millipedes, characterized by modified male gonopods. The species is endemic to the Midwestern United States, with confirmed records from Ohio.
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.
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.
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.
Pleuroloma
Pleurolomas
Pleuroloma is a genus of flat-backed millipedes in the family Xystodesmidae, distinguished by its great age, extensive geographic range, and ecological adaptability. The genus comprises four recognized species, with P. flavipes being the most widespread, ranging from the eastern Atlantic Coast to the central Great Plains. Members exhibit distinctive aggregating and migrating behaviors, particularly P. flavipes, which may contribute to its broad distribution. The genus is unique within Xystodesmidae for these behavioral traits and its ability to colonize diverse habitats.
Pleuroloma cala
Pleuroloma cala is a flat-backed millipede in the family Xystodesmidae, endemic to peninsular Florida south of the Suwannee River. It is one of four recognized species in the genus Pleuroloma, distinguished from the widespread P. flavipes by subtle morphological differences in segmental profile, sternal configuration, and male gonopod structure. The species was originally described as Zinaria cala by Chamberlin in 1939.
Polydesmida
Flat-backed Millipedes
Polydesmida is the largest order of millipedes, containing over 5,000 described species. Members are commonly known as flat-backed millipedes due to the presence of lateral keels (paranota) on most body segments. This order includes all millipedes known to produce hydrogen cyanide (HCN) as a chemical defense. Polydesmids are found on every continent except Antarctica and exhibit the highest morphological diversity among millipede orders. They are characterized by a unique developmental mode called teloanamorphosis, in which adults reach a fixed number of segments and cease molting.
Pseudopolydesmus canadensis
Canadian Flat-back Millipede, Canadian flat-backed millipede
Pseudopolydesmus canadensis is a species of flat-backed millipede in the family Polydesmidae, characterized by a prominent black mid-dorsal stripe running along its body. The species is native to North America, with established populations in Canada and the United States, and has been introduced to Europe including Germany. It is one of the more commonly observed millipede species in its range, with over 2,200 documented observations on community science platforms.
Pseudopolydesmus paludicolus
Pseudopolydesmus paludicolus is a species of flat-backed millipede in the family Polydesmidae, described by Hoffman in 1950. It belongs to a genus characterized by a flattened body form typical of polydesmidan millipedes. The species epithet 'paludicolus' (from Latin 'palus' meaning marsh and 'cola' meaning dweller) suggests association with wetland or marshy habitats. Documentation of this species remains limited, with few published records beyond original description.
Pseudopolydesmus pinetorum
A small polydesmid millipede species first described by Bollman in 1888. The species name 'pinetorum' refers to its association with pine forest habitats. A laboratory study has documented aspects of its reproduction and growth, though detailed natural history information remains limited.
Pseudopolydesmus serratus
Common Pink Flat-back
Pseudopolydesmus serratus is a species of flat-backed millipede in the family Polydesmidae, commonly known as the Common Pink Flat-back. It was first described by Thomas Say in 1821 and is widely distributed across North America. The species has been the subject of recent morphological research using 3D imaging techniques to study its anatomy and genitalia development.
Rhysodesmus
Rhysodesmus is a genus of flat-backed millipedes in the family Xystodesmidae, established by Cook in 1895. The genus contains at least 90 described species, with Rhysodesmus dasypus serving as the type species and recognized as the largest known xystodesmid millipede. Species in this genus range from El Salvador northward through Mexico to the southern United States. The genus is taxonomically significant within the Polydesmida order but remains incompletely characterized for many species.
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.
Rudiloria
Rudiloria is a genus of flat-backed millipedes in the family Xystodesmidae, endemic to eastern North America. The genus contains seven described species, including the widespread R. trimaculata. Members are characterized by their flattened bodies and distinct color patterns. The genus was established by Causey in 1955.
Rudiloria trimaculata
Bob's Yellow and Black Millipede
Rudiloria trimaculata is a flat-backed millipede in the family Xystodesmidae, recognized by the proposed common name Bob's Yellow and Black Millipede. The species occurs in the northeastern United States and southeastern Canada. Two subspecies are recognized: R. t. trimaculata and R. t. tortua.
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.
Scytonotus granulatus
granulated millipede
Scytonotus granulatus, commonly known as the granulated millipede, is a species of flat-backed millipede in the family Polydesmidae. It is native to North America and was first described by Thomas Say in 1821 under the basionym Polydesmus granulatus. As a member of the Polydesmida order, it exhibits the characteristic flattened body form typical of flat-backed millipedes.
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.
Semionellus
Semionellus is a genus of flat-backed millipedes in the family Xystodesmidae, established by Chamberlin in 1920. The genus contains at least three described species: S. michiganus, S. placidus, and S. tertius. Members are found in the north-central and northeastern United States, including Michigan, Indiana, Ohio, Minnesota, and Maryland. As xystodesmid millipedes, they share the characteristic flattened body form typical of this diverse family of polydesmidan millipedes.
Semionellus placidus
Salmon Cherry Millipede
Semionellus placidus is a species of flat-backed millipede in the family Xystodesmidae, commonly known as the Salmon Cherry Millipede. It is a North American species characterized by its polydesmidan body plan with a flattened dorsal profile. As a member of the Xystodesmidae, it belongs to one of the most diverse families of millipedes in North America. The species was described by Wood in 1864.
Sigmocheirini
Sigmocheirini is a tribe of flat-backed millipedes (Order Polydesmida) in the family Xystodesmidae, established by Causey in 1955. The tribe contains the genus Sigmocheir, whose species are endemic to California's Sierra Nevada foothills. Members of this tribe exhibit the characteristic flattened body form typical of xystodesmid millipedes.
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.
Sigmoria australis
Sigmoria australis is a flat-backed millipede in the family Xystodesmidae, described by Shelley in 1986. It belongs to the order Polydesmida, a group characterized by their dorsoventrally flattened bodies and distinct lateral extensions (paranota) on each segment. The species is known from North America, with confirmed records from Florida.
Sigmoria bidens
Sigmoria bidens is a species of flat-backed millipede in the family Xystodesmidae, described by Causey in 1942. It belongs to the order Polydesmida, one of the largest orders of millipedes, characterized by their flattened bodies and keeled tergites. The genus Sigmoria is part of the tribe Apheloriini within the subfamily Rhysodesminae. Very few observations of this species have been documented, with only 8 records in iNaturalist as of the knowledge cutoff.
Sigmoria latior
Red-sided Flat Millipede
Sigmoria latior is a flat-backed millipede in the family Xystodesmidae, commonly known as the Red-sided Flat Millipede. The species was described by Brölemann in 1900 and is native to North America. Four subspecies are recognized, including the nominate subspecies S. l. latior and S. l. hoffmani, S. l. mariona, and S. l. munda. As a member of the tribe Apheloriini, it belongs to a group of xystodesmid millipedes known for their often striking coloration.
Xystocheir brachymacris
Xystocheir brachymacris is a species of flat-backed millipede in the family Xystodesmidae, native to North America. Like other members of its family, it possesses chemical defense glands capable of producing hydrogen cyanide gas when disturbed. The species was described by Shelley in 1996.
Xystocheir dissecta
Xystocheir dissecta is a flat-backed millipede in the family Xystodesmidae. It is found along the coast of Northern California, particularly in and around the San Francisco Bay Area. The species is notable for its chemical defense system, producing hydrogen cyanide gas when threatened. Three subspecies are recognized: X. d. dissecta, X. d. microrama, and X. d. taibona.