Millipede
Guides
Orinisobates
Orinisobates is a genus of millipedes in the family Nemasomatidae, order Julida. It was established by Lohmander in 1933. The genus contains multiple species distributed across parts of Eurasia and has been introduced to North America. Members are small to medium-sized juliform millipedes with the elongated cylindrical body form characteristic of the order.
Orinisobates expressus
Orinisobates expressus is a millipede species in the family Nemasomatidae, first described by Chamberlin in 1941. It belongs to the order Julida, a diverse group of cylindrical millipedes. The species has been documented in Alberta, Canada, with approximately 50 iNaturalist observations contributing to its known distribution.
Orophe
Orophe is a genus of robust millipedes in the family Xystodesmidae, endemic to the Rocky Mountains of northern Idaho and western Montana. The genus contains two species: Orophe unicus and Orophe cabinetus. Both species are large-bodied with similar coloration featuring yellow paranota and central yellow patches on the tergites, differing only in gonopod morphology.
Orophe unicus
Orophe unicus is a robust millipede in the family Xystodesmidae endemic to the Rocky Mountains of northern Idaho. Originally described as Chipus unicus in 1953, it was transferred to Orophe in 1964 and has undergone taxonomic revision due to its close similarity to Orophe cabinetus. The species is distinguished from its sister species primarily by subtle differences in gonopod structure and by geographic separation, though recent observations suggest their ranges may be closer than previously recognized.
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.
Orthomorpha coarctata
Long-flange Millipede
Orthomorpha coarctata is a widely introduced millipede species in the family Paradoxosomatidae, commonly known as the long-flange millipede. Presumed native to Southeast Asia, it has established populations in tropical and subtropical regions worldwide through human-mediated transport. The species is notable for its distinctive elongated paranota (lateral keels) and unique male gonopod morphology. Some taxonomists have placed it in the monotypic genus Asiomorpha based on these reproductive structures.
Orthoporus
Orthoporus is a genus of spirostreptid millipedes comprising approximately 80 species distributed from the southern United States through Central America to Brazil and Argentina. The genus includes the well-known desert millipede Orthoporus ornatus, which has been studied for its behavioral thermoregulation in arid environments. Members of this genus are characterized by their cylindrical bodies and two pairs of legs per body segment, typical of millipedes. Several species are maintained in educational collections due to their docile nature and distinctive appearance.
Orthoporus flavior
Orthoporus flavior is a large spirostreptid millipede native to the southwestern United States and Mexico. The species is characterized by its cylindrical body form, slow movement, and distinctive yellow-gold banding along the dorsal surface. It belongs to a genus commonly known as desert millipedes, though specific ecological details for this species remain limited in published literature.
Orthoporus ornatus
Desert Millipede, Texas Gold-Banded Millipede
Orthoporus ornatus is a large millipede native to the Chihuahuan and Sonoran deserts of the southwestern United States and northern Mexico. Adults typically reach 4 inches (10 cm) in length, with exceptional individuals exceeding 9 inches (23 cm). The species exhibits behavioral thermoregulation, spending most of its life in deep, damp soil burrows and emerging primarily after summer rains to feed and reproduce. It is popular in the pet trade and has been introduced to European collections through captive breeding programs.
Orthoporus texicolens
Orthoporus texicolens is a millipede species in the family Spirostreptidae, described by Chamberlin in 1938. It belongs to a genus of large, cylindrical millipedes commonly known as desert millipedes. The species is distributed across Central America and North America. Like other members of its genus, it is likely a detritivore adapted to arid and semi-arid environments.
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.
Paeromopus
Paeromopus is a genus of large cylindrical millipedes endemic to California, United States. The genus contains four species, with body lengths ranging from 10 to 16.5 cm, making P. paniculus the longest millipede species in North America. Three species have restricted ranges in the Sierra Nevada mountains, while P. angusticeps has a broad distribution across Northern California and the Central Coast. The genus was established by Ferdinand Karsch in 1881 and belongs to the family Paeromopodidae.
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.
Parajulidae
Parajulid Millipedes
Parajulidae is a family of millipedes in the order Julida, distinguished by male genital morphology: males possess greatly enlarged first pairs of legs and externally exposed gonopods. The family occurs predominantly in North America with extensions into Central America and East Asia, representing one of the most widely distributed millipede families in the Western Hemisphere. The genus Oriulus venustus alone covers three-fourths of the continental United States and adjacent southern Canada, making it the most broadly distributed North American diplopod known.
Petaserpes cryptocephalus
Slug Millipede
Petaserpes cryptocephalus is a millipede species in the family Polyzoniidae, commonly known as the slug millipede. It is found in North America, with records from Vermont and other parts of the United States. The species belongs to the order Polyzoniida, a group of small, flattened millipedes sometimes referred to as "slug millipedes" due to their distinctive body form.
Petaserpes strictus
Petaserpes strictus is a millipede species in the family Polyzoniidae, described by Shelley in 1976. It belongs to the order Polyzoniida, a group of small, often flattened millipedes. The species is recorded from North America. Very few observations exist, with only one documented record in iNaturalist.
Platydesmida
Feather Millipedes
Platydesmida is an order of millipedes containing two families (Andrognathidae and Platydesmidae) and over 60 described species. Members are characterized by a strongly flattened body with lateral extensions (paranota) on each segment. The order is notable for containing some of the few documented examples of paternal care in arthropods, with males of certain species coiling around and guarding eggs and young. The only known fossil record consists of a specimen from mid-Cretaceous Burmese amber (~100 Ma) belonging to the extant genus Andrognathus.
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.
Polydesmidae
flat-backed millipedes, tractor millipedes
Polydesmidae is a family of millipedes in the order Polydesmida comprising over 240 species across more than 30 genera. These millipedes are characterized by their flattened, plate-like dorsal exoskeletons that give them the common name "flat-backed millipedes." They range from 4 mm to 30 mm in length and display coloration from black through brownish to pallid, rarely vivid. The family has a predominantly Holarctic distribution extending to Mexico, North Africa, and Java, with highest diversity in the Mediterranean region. Several species exhibit notable biological traits, including sexual dimorphism in segment number and chemical defense secretions.
Polyxenida
bristle millipedes, bristly millipedes, pincushion millipedes
Polyxenida is an order of millipedes distinguished by a soft, non-calcified exoskeleton covered in distinctive tufts of bristles. They are the only living members of the subclass Penicillata, which represents the most basal lineage of living millipedes. This order comprises approximately 148 species across four families worldwide. Polyxenida exhibit several unique derived traits including indirect sperm transfer via spermatophores deposited in webs, and a mechanical defense using detachable barbed bristles rather than chemical defenses.
Polyxenidae
pincushion millipedes, bristly millipedes
Polyxenidae is a family of small millipedes in the subclass Penicillata, characterized by distinctive bundles of bristles (setae) at the posterior end. Adults range from 1.2–4.2 mm in length and possess 13 pairs of legs with 10 tergites anterior to the telson. The family contains approximately 109 species across 23 genera, distributed worldwide except Antarctica. Males produce spermatophores delivered via specialized pores on leg pairs 6–11.
Polyxenus
Polyxenus is a genus of bristly millipedes in the order Polyxenida, the sole extant genus of the family Polyxenidae. These small millipedes are characterized by their distinctive tufts of setae (bristles) and are notable for being among the most morphologically derived millipedes, having lost many ancestral diplopod traits. The genus contains at least 30 valid species and has a broad geographic distribution across multiple continents. Polyxenus species are frequently found in association with ants, serving as either symbionts or specialized prey.
Polyxenus lagurus
Bristly Millipede
Polyxenus lagurus, commonly known as the bristly millipede, is a small millipede species distinguished by its detachable defensive bristles that entangle attacking ants and spiders. It exhibits a unique reproductive polymorphism, with some populations reproducing sexually and others parthenogenetically. This species undergoes hemianamorphosis, adding segments and legs through juvenile molts until reaching a fixed adult complement of 13 leg pairs and 10 tergites, after which molting continues without further segment addition. It is the most common polyxenid in Europe and the only representative of order Polyxenida in the British Isles.
Polyzoniida
camphor millipedes
Polyzoniida is an order of millipedes in the subterclass Colobognatha, containing three families (Hirudisomatidae, Polyzoniidae, Siphonotidae) and more than 70 described species. These millipedes are commonly known as camphor millipedes due to the strong camphor-like odor of their defensive secretions. They range from 4–50 mm in length, typically 10–15 mm, with a domed dorsal surface and flat ventral side. Their defensive chemistry has ecological significance: poison frogs in South America and Madagascar have been observed to sequester toxins from these millipedes.
Proteroiulus fuscus
Ochre Snake Millipede
Proteroiulus fuscus is a small European millipede in the family Blaniulidae, commonly known as the Ochre Snake Millipede. It exhibits sexual dimorphism in body size, with females notably larger than males. The species has a widespread but patchy distribution across Europe, being absent from several countries in the Balkans and Mediterranean region as well as various European islands.
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 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.
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.
Ptyoiulus
Ptyoiulus is a genus of millipedes in the family Parajulidae, established by Cook in 1895. The genus contains approximately seven described species distributed in eastern North America. Species within this genus are cylindrical millipedes characterized by features typical of the Julida order. The genus is taxonomically placed in the subfamily Ptyoiulinae.
Ptyoiulus impressus
Flocculent Tailed Millipede
Ptyoiulus impressus is a species of millipede in the family Parajulidae, commonly known as the Flocculent Tailed Millipede. It was described by Thomas Say in 1821 and is found in North America. The species belongs to the order Julida, which contains many common cylindrical millipedes. As a member of the Ptyoiulinae subfamily, it shares characteristics with other Parajulidae including relatively elongated bodies and typical juliform morphology.
Rhinotus
Rhinotus is a genus of millipedes in the family Siphonotidae, order Polyzoniida, containing at least 20 described species. The genus includes notable cosmopolitan tramp species such as Rhinotus purpureus, which has been repeatedly described as new under multiple synonyms and is frequently associated with human-modified environments.
Rhinotus purpureus
purple millipede
A small, cosmopolitan millipede species in the family Siphonotidae, native to the Neotropics but widely introduced globally through human commerce. Frequently found in greenhouses and other synanthropic habitats, it has been repeatedly described as new due to its variable appearance, resulting in over a dozen synonyms. First recorded from the Indian subcontinent in 2020.
Rhiscosomididae
Rhiscosomididae is a small family of millipedes in the order Chordeumatida, containing the single genus Rhiscosomides with seven described species. The family was established by Silvestri in 1909. These millipedes are known from western North America, with records from British Columbia, Washington, Oregon, and California.
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.
Scoterpes
Scoterpes is a genus of troglobiotic millipedes in the family Trichopetalidae, order Chordeumatida. Established by Cope in 1872, the genus comprises exclusively cave-dwelling species found in North America. The genus was revised in 2010, with fifteen recognized species including eight newly described taxa. At least two species, S. copei and S. ventus, likely represent superspecies complexes consisting of multiple genetically isolated populations.
Scoterpes sollmani
Scoterpes sollmani is a troglobiotic millipede described by Lewis in 2000 from cave systems in southern Indiana. As a member of genus Scoterpes, it is one of multiple cave-adapted species in this exclusively troglobiotic group. The species belongs to the small family Trichopetalidae within the order Chordeumatida, a group of small-bodied millipedes. No specific morphological details distinguishing S. sollmani from congeners are provided in available sources.
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.