| Chilognatha Temporal range: | |
|---|---|
 | |
| Polydesmus angustus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Myriapoda |
| Class: | Diplopoda |
| Subclass: | Chilognatha Latrielle, 1802 |
Chilognatha is a subclass of the class Diplopoda, which includes the vast majority of extant millipedes, about 12,000 species.
The classification of Chilognatha presented below is based on Shear, 2011, [1] and Shear & Edgecombe, 2010 [2] (extinct groups). Recent cladistic and molecular studies have challenged the traditional classification schemes above, and in particular the position of the orders Siphoniulida and Polyzoniida is not yet well established. [3] The placement and positions of extinct groups (†) known only from fossils is tentative and not fully resolved. [3] [2] After each name is listed the author citation: the name of the person who coined the name or defined the group, even if not at the current rank.
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.
Arthropleuridea is an extinct subclass of myriapod arthropods that flourished during the Carboniferous period, having first arose during the Silurian, and perishing in the Early Permian. Members are characterized by possessing diplosegement paranotal tergal lobes separated from the body axis by a suture, and by sclerotized plates buttressing the leg insertions. Despite their unique features, recent phylogenetic research suggests Arthropleuridea be included among millipedes in the class Diplopoda. The subclass contains three recognized orders, each with a single genus.
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.
Spirobolida is an order of "round-backed" millipedes containing approximately 500 species in 12 families. Its members are distinguished by the presence of a "pronounced suture that runs "vertically down the front of the head". Most of the species live in the tropics, and many are brightly coloured. Mature males have two pairs of modified legs, the gonopods, consisting of the 8th and 9th leg pair: the posterior gonopods are used in sperm-transfer while the anterior gonopods are fused into a single plate-like structure.
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.
Sphaerotheriida is an order of millipedes in the infraclass Pentazonia, sometimes known as giant pill millipedes. They inhabit Southern Africa, Madagascar, South and Southeast Asia, Australia and New Zealand. Like the Northern Hemisphere pill millipedes of the order Glomerida, these millipedes can roll into a ball when disturbed. When they are rolled-up, most sphaerotheriidans reach a maximum size of a cherry or golf ball, but some species from Madagascar can even reach the size of an orange. When rolled-up, predators are unable to unravel giant pill millipedes since the margins of their second and last dorsal plates fit perfectly into one another, creating a sealed ball. A few giant pill millipede species are able to produce sound, the only millipedes known to do this. This order of millipedes is also unique in that some African species are used for medicinal purposes.
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.
Zephroniidae is a family of giant pill millipedes in the taxonomic order Sphaerotheriida. They occur in southeast Asia from the Himalayas and China south and east to Sulawesi and to Australia, and also inhabit some Philippine islands.
Polyxenida is an order of millipedes readily distinguished by a unique body plan consisting of a soft, non-calcified body ornamented with tufts of bristles – traits that have inspired the common names "bristly millipedes" or "pincushion millipedes". There are at least 86 species in four families worldwide, and are the only living members of the subclass Penicillata.
Polyzoniida is an order of millipedes in the subterclass Colobognatha containing three families and at least 74 described species.
Colobognatha is a clade of helminthomorph millipedes containing four orders: Platydesmida, Polyzoniida, Siphonocryptida, and Siphonophorida.
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.
Siphoniulus is a poorly known genus of millipede containing only two living species: S. alba from Indonesia, and S. neotropicus from Mexico and Guatemala. An additional two fossil species are known from Cretaceous amber. Siphoniulus species are the only members of the family Siphoniulidae and order Siphoniulida, making Siphoniulida the smallest millipede order. Few specimens are known, and their classification is contentious, although most recent studies place them as basal members of the Helminthomorpha.
Siphonorhinidae is a family of millipede in the order Siphonophorida. There are at least 4 genera and about 12 described species in Siphonorhinidae.
Siphonophoridae is a family of millipede in the order Siphonophorida. There are about 12 genera and more than 110 described species in Siphonophoridae.
Andrognathidae is a family of millipede in the order Platydesmida. There are about 17 genera and more than 30 described species in Andrognathidae.
Rhachodesmidae is a family of flat-backed millipedes in the order Polydesmida. There are more than 20 genera and at least 80 described species in Rhachodesmidae.
Spirobolellidae is a family of millipedes in the order Spirobolida. There are about 11 genera and more than 100 described species in Spirobolellidae.
Orders of the class Diplopoda (millipedes) | |||||||||||||||||||||||||||||||
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