Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a result of two single segments fused together. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a tight ball. Although the name "millipede" derives from Latin for "thousand feet", no species was known to have 1,000 or more until the discovery in 2020 of Eumillipes persephone, which can have over 1,300 legs. There are approximately 12,000 named species classified into 16 orders and around 140 families, making Diplopoda the largest class of myriapods, an arthropod group which also includes centipedes and other multi-legged creatures.
Pill millipedes are any members of two living orders of millipedes, often grouped together into a single superorder, Oniscomorpha. The name Oniscomorpha refers to the millipedes' resemblance to certain woodlice (Oniscidea), also called pillbugs or "roly-polies". However, millipedes and woodlice are not closely related ; rather, this is a case of convergent evolution.
Harpaphe haydeniana, commonly known as the yellow-spotted millipede, almond-scented millipede or cyanide millipede, is a species of polydesmidan ("flat-backed") millipede found in the moist forests along the Pacific coast of North America, from Southeast Alaska to California. The dark coloration with contrasting yellow-tipped keels warn of its ability to exude toxic hydrogen cyanide as a defense. The cyanide secretions are not dangerous to humans, but can cause irritation and pain if it contacts sensitive areas such as the mouth, eyes, or nose.
Glomerida is an order of pill-millipedes found primarily in the Northern Hemisphere. Also known as northern pill millipedes, they superficially resemble pill-bugs or woodlice, and can enroll into a protective ball. They have twelve body segments, 17 to 19 pairs of legs, and males have enlarged rear legs involved in mating. The order includes about 30 genera and at least 280 species, including Glomeris marginata, the common European pill-millipede. The order contains members in Europe, South-east Asia and the Americas from California to Guatemala. Although historically considered closely related with the similar sphaerotheriidans that also enroll, some DNA evidence suggest they may be more closely related to glomeridesmidans, a poorly known order that does not enroll.
Polydesmida is the largest order of millipedes, containing approximately 3,500 species, including all the millipedes reported to produce hydrogen cyanide (HCN). Polydesmids grow and develop through a series of moults, adding segments until they reach a fixed number in the adult stage, which is usually the same for a given sex in a given species, at which point the moulting and the addition of segments and legs stop. This mode of development, known as teloanamorphosis, distinguishes this order from most other orders of millipedes, which usually continue to moult as adults, developing through either euanamorphosis or hemianamorphosis.
Ommatoiulus moreleti, commonly known as the Portuguese millipede, is a herbivorous millipede native to the western Iberian Peninsula where it shares its range with other Ommatoiulus species. From here, it has spread by international commerce to a number of new localities. This species was accidentally introduced into Australia without its natural enemies and has since become an invasive pest. A number of methods have been developed to manage this millipede.
Julida is an order of millipedes. Members are mostly small and cylindrical, typically ranging from 10–120 millimetres (0.39–4.72 in) in length. Eyes may be present or absent, and in mature males of many species, the first pair of legs is modified into hook-like structures. Additionally, both pairs of legs on the 7th body segment of males are modified into gonopods.
Ommatoiulus is a genus of millipedes in the family Julidae.
Chordeumatida is a large order of millipedes containing some 1200 species with a nearly worldwide distribution. Also known as sausage millipedes, they grow and develop through a series of moults, adding segments until they reach a fixed number in the adult stage, which is usually the same for a given sex in a given species, at which point the moulting and the addition of segments and legs stop. This mode of development, known as teloanamorphosis, distinguishes this order from most other orders of millipedes, which usually continue to moult as adults, developing through either euanamorphosis or hemianamorphosis.
Casimir Albrecht Willem Jeekel (1922–2010) was a Dutch myriapodologist and entomologist known for his major contributions to the taxonomy of millipedes. His 1971 monograph Nomenclator Generum et Familiarum Diplopodorum is credited as launching the "modern era" of millipede taxonomy, and has been considered the "most important single work ever published on the Diplopoda". He served as director of the Zoological Museum Amsterdam, and authored over 150 works on the taxonomy of millipedes and other myriapods.
Titanophyllum spiliarum is a species of cave-dwelling millipede in the family Julidae. The only known species of the genus Titanophyllum, it was described in 2011 from specimens discovered in a cave in Greece. It has several unusual characteristics including eyelessness and a small hook on its hind-most body section that may be involved in keeping the animal ‘locked’ when it coils-up defensively.
Arthrosphaeridae is a family of giant pill millipedes that are found in Madagascar, the Western Ghats of India, and Sri Lanka. The largest pill-millipede in the world, Zoosphaerium neptunus belongs to this family and is known to swarm at certain times of the year.
Pyrgodesmidae is a family of flat-backed millipedes in the order Polydesmida. The family contains over 200 species distributed in tropics around the world. Some species are found only in ant colonies, and are considered obligate myrmecophiles.
Narceus gordanus is a spirobolid millipede native to the southeastern United States. Common names include Smokey Oak Millipede and Smokey Ghost Millipede. Adults range from around 60 to 120 mm in length, up to 13 mm wide, and possess 45 to 65 body segments. The body color is lighter than other species of Narceus, with each body ring a light greenish tan followed by a band of darker tan. N. gordanus also has shorter legs than other Narceus species, and a deeper groove on the head in which the antennae rest.
Ommatoiulus avatar is a species of European millipede in the family Julidae. Individuals are known from Andalusia, southern Spain. Individuals are 25 to 38 mm long. Color in alcohol preserved specimens is brownish with yellowish and black marbling on the dorsal surface. O. avatar was described in 2015, with the aid of X-ray microtomography that produced a three-dimensional digital model, becoming the first millipede described from reference to physical type specimens as well as virtual models, known as "cybertypes".
Ommatoiulus sabulosus aimatopodus is a millipede occurring in the South of France; belonging to the same species than Ommatoiulus sabulosus, it differs from the type by the lack of lighter transversal lines on the back when adult. It is believed to be a Mediterranean-climate adapted variant, but whether it is a true subspecies or rather an ecomorph is unclear; first described by Antoine Risso as a distinct species, it is for now considered as a form of Ommatoiulus sabulosus, under the name Ommatoiulus sabulosus f. aimatopodus.
Cylindroiulus caeruleocinctus is a species of millipede in the family Julidae.
Glomeris hexasticha, also known as the eastern six-striped pill millipede or the diagonal-striped pill millipede, is a species of pill millipede within the family Glomeridae and order Glomerida. The pill millipede is widely distributed within many European countries, with the species consisting of over twenty different subspecies.
