| Platyrhacidae | |
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| Nyssodesmus python from Central America | |
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| Family: | Platyrhacidae Pocock, 1895 |
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c. 50 [1] | |
| Synonyms | |
Platyrrhacidae | |
Platyrhacidae is a family of polydesmidan millipedes distributed in Southeast Asia and tropical Central and South America.
Platyrhacids are often large and colorful. They can be distinguished from most other polydesmidans by having ozopores situated further inward from the paranota margins, ozopores surrounded by a broad, flat ring, and presence of compound setae on the labrum and often on the epiproct (a posterior extension of the telson). The gonopods in males are relatively simple, although up to five gonopodal processes ("branches") may be present in some genera from Borneo. [2] [3] Large platyrhacids in Borneo may grow up to 13 cm (5.1 in) long and exhibit colors of blue, green, and yellow with black spots or stripes. [4] The largest known species in the order Polydesmida, however, is a platyrhacid species found in Sumatra, Gigantorhacus mirandus, which can reach 134 mm (5.3 in) in length. [5]
Platyrhacids occur in two disjunct geographic areas. The majority of species occur in Southeast Asia, including the Greater Sunda Islands and the Philippine archipelago. The rest occur in the New World Tropics from Nicaragua to Peru, as well as on some Caribbean islands. [3] [6]
The Platyrhacidae is part of the larger suborder Chelodesmidea. The family Platyrhacidae is subdivided into several groups, formerly considered tribes but elevated to the status of subfamilies in 2013. [6]
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The following genera have not yet been placed into a subfamily [6]
The family (originally misspelled "Platyrrhacidae") was named by Reginald Pocock in 1895 to include the single genus Platyrhacus . Shortly after, Orator F. Cook added Acanthodesmus , Odontodesmus , and Trachelodesmus . By 1897, additional works by Cook, Pocock, and Filippo Silvestri had increased the number of genera to 37.
The North American genera Euryurus , Auturus , and Illiniurus , were long-considered to constitute a sub-group of Platyrhacidae (i.e. the subfamily Euryurinae or tribe Euryurini in various classifications), until separated as a distinct family (Euryuridae) by Hoffman in 1998 and allied closer to Xystodesmidae. Similarly and concurrently, several neotropical genera previously placed in other subgroups of Platyrhacidae were removed and elevated to full family status: the Aphelidesmidae. [2]
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.
Chilognatha is a subclass of the class Diplopoda, which includes the vast majority of extant millipedes, about 12,000 species.
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.
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.
Xystodesmidae is a family of millipedes. Its members often have very small distributional areas, with many species only known from a single locality. They are found across the northern hemisphere, with peak diversity in the Appalachian Mountains, where one-third of the 300 or so species occur. They are particularly abundant in deciduous broadleaf forests in the Mediterranean Basin, Africa, Asia, Central and North America, and Russia. Information on basic taxonomy is scant for this family; for example, it is estimated that the genus Nannaria contains over 200 species, but only 25 were described as of 2006. By 2022, 78 species in Nannaria have been described.
Paradoxosomatidae, the only family in the suborder Paradoxosomatidea, is a family of flat-backed millipedes in the order Polydesmida. Containing nearly 200 genera and 975 species as of 2013, it is one of the largest families of millipedes. Paradoxosomatids occur on all continents except Antarctica, and can generally be distinguished by dorsal grooves on most body segments and a dumb-bell shaped gonopod aperture. Notable groups within the Paradoxosomatidae include the dragon millipedes of Southeast Asia, and the widely introduced greenhouse millipede Oxidus gracilis.
Tridontomidae is a small family of millipedes. Its members are endemic to Guatemala. These millipedes range from 22 mm to 28 mm in length and are uniformly grayish in color; their legs and antennae are unusually long and slender. This family includes the remarkable species Aenigmopus alatus, in which adult males feature no gonopods. This millipede is the only species in the infraclass Helminthomorpha without gonopods.
Richard Lawrence Hoffman was an American zoologist known as an international expert on millipedes, and a leading authority on the natural history of Virginia and the Appalachian Mountains. He was a biology professor at Virginia's Radford College for almost thirty years, and curator of invertebrates at the Virginia Museum of Natural History for another twenty years. He co-founded the Virginia Natural History Society, described over 400 species of millipedes, and produced more than 480 scientific publications. He is commemorated in the scientific and/or common names of over 30 animal species, including the valley and ridge salamander and Hoffman's dwarf centipede.
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.
Harold Frederick Loomis was an American botanist and myriapodologist known for his contributions to agronomy, plant pathology, and millipede taxonomy. He worked for the U.S. Department of Agriculture for over four decades, studying diseases of crop plants, and was a colleague of Orator F. Cook. He also made major contributions to the natural history of Central America and the West Indies, naming over 500 species of millipedes in total. He co-described with Cook the leggiest animal on earth: Illacme plenipes, with over 700 legs.
Orthomorpha coarctata, the long-flange millipede, is a widely introduced species of Polydesmidan millipede of the family Paradoxosomatidae. It is presumed native to Southeast Asia but due to transport by humans occurs in tropical and sub-tropical areas throughout the world, including the Hawaiian Islands, the West Indies, Gulf Coast of North America, and the Galápagos Islands.
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.
Psammodesmus is a genus of platyrhacid millipedes found from Panama to Peru. The 11 species constitute the platyrhacid subfamily Psammodesminae.
Haplodesmidae is a family of millipedes in the order Polydesmida. Species occur in East Asia, Southeast Asia, and Oceania, although some species have been introduced to the New world tropics. Species are small bodied, often with elaborate sculpturing on the tergites, and some species are capable of rolling into a near-complete ball.
Ammodesmidae is a family of small millipedes endemic to Africa, containing seven species in two genera. Ammodesmids range from 1.4 to 5.0 mm long with 18 or 19 body segments in both sexes, and are capable of rolling into a tight sphere.
Fuhrmannodesmidae is a family of millipedes belonging to the order Polydesmida. The family includes over 50 genera. This family includes three species notable for being among the very few species in this order to feature adults with only 18 segments rather than the 20 segments usually found in polydesmids. This family also includes several genera notable for featuring sexual dimorphism in segment number: adult females in these genera have the usual 20 segments, but adult males have only 19. Millipedes in these species arrive at these lower numbers of segments by going through the same stages of teloanamorphosis observed in other polydesmids but reaching maturity one moult earlier for 19 segments or two moults earlier for 18 segments.
Sphaeriodesmidae is a family of flat-backed millipedes in the order Polydesmida. There are about 15 genera and at least 90 described species in Sphaeriodesmidae.
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.
Stenoniodes, commonly known as the Borneo tractor millipede, is a genus of millipede in the family Platyrhacidae. It contains six species, five of which occur on Borneo and one on Sibutu Island. Its common name originates from the likeness of its 20-segmented body to the tread of a tractor's tire.
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