Platyrhacidae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

polydesmida Polydesmida (from the Greek ''poly'' "many" and ''desmos'' "bond") is the largest order of millipedes, containing approximately 3,500 species, including all the millipedes reported to produce hydrogen cyanide (HCN). Description Members of the or ...

millipede 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 re ...

s distributed in Southeast Asia and tropical Central and South America.

Description

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 In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. ...

on the labrum and often on the epiproct (a posterior extension of the

telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...

). The

gonopod Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millipe ...

s in males are relatively simple, although up to five gonopodal processes ("branches") may be present in some genera from

Borneo Borneo (; id, Kalimantan) is the List of islands by area, third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java Isl ...

. Large platyrhacids in Borneo may grow up to long and exhibit colors of blue, green, and yellow with black spots or stripes.

Distribution

Platyrhacids occur in two disjunct geographic areas. The majority of species occur in Southeast Asia, including the

Greater Sunda Islands The Greater Sunda Islands (Indonesian and Malay: ''Kepulauan Sunda Besar'') are four tropical islands situated within Indonesian Archipelago, in the Pacific Ocean. The islands, Borneo, Java, Sulawesi and Sumatra, are internationally recognise ...

and the

Philippine archipelago As an archipelago, the Philippines comprises about 7,641 islands clustered into three major island groups: Luzon, the Visayas, and Mindanao. Only about 2,000 islands are inhabited,

. The rest occur in the New World Tropics from

Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest Sovereign state, country in Central America, bordered by Honduras to the north, the Caribbean Sea, Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, as well as on some

Caribbean islands Almost all of the Caribbean islands are in the Caribbean Sea, with only a few in inland lakes. The largest island is Cuba. Other sizable islands include Hispaniola, Jamaica, Puerto Rico and Trinidad and Tobago. Some of the smaller islands a ...

Classification

The Platyrhacidae is part of the larger suborder

Chelodesmidea Leptodesmidea is a suborder of flat-backed millipedes under the order Polydesmida Polydesmida (from the Greek language, Greek ''poly'' "many" and ''desmos'' "bond") is the largest order (biology), order of millipedes, containing approximately ...

. The family Platyrhacidae is subdivided into several groups, formerly considered

tribes The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

but elevated to the status of subfamilies in 2013. Psammodesmus bryophorus

* Barydesminae - Neotropical America **'' Barydesmus'' **''

Nyssodesmus ''Nyssodesmus'' is a genus of flat-backed millipedes in the family Platyrhacidae. About a dozen species have been described, all native to Central America, occurring from Nicaragua to Panama. pp. 378-379 Species *'' Nyssodesmus alboalatus'' *'' ...

'' **'' Tyrodesmus'' * Diodontodesminae -

Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its ca ...

**'' Diodontodesmus'' * Erythrhacinae * Hoplurorhachinae - Borneo * Phyodesminae- Borneo **'' Phyodesmus'' * Polydesmorhachinae - Palawan island, Philippines * Psammodesminae - Neotropical America **'' Psammodesmus'' * Psaphodesminae - Indonesia, east of Wallace's line * Taphodesminae **'' Taphodesmus'' ;Unplaced The following genera have not yet been placed into a subfamily *'' Hoffmanorhacus'' *'' Nanorrhacus'' *'' Proaspis''

Classification history

The family (originally misspelled "Platyrrhacidae") was named by Reginald Pocock in 1895 to include the single genus '' Platyrhacus''. Shortly after,

Orator F. Cook Orator Fuller Cook Jr. (May 28, 1867 – April 23, 1949) was an American botanist, entomologist, and agronomist, known for his work on cotton and rubber cultivation and for coining the term "speciation" to describe the process by which new species ...

added '' Acanthodesmus'', '' Odontodesmus'', and '' Trachelodesmus''. By 1897, additional works by Cook, Pocock, and

Filippo Silvestri Filippo Silvestri (22 June 1873 – 10 June 1949) was an Italian entomologist. He specialised in world Protura, Thysanura, Diplura and Isoptera, but also worked on Hymenoptera, Myriapoda and Italian Diptera. He is also noted for describing an ...

had increased the number of genera to 37. The North American genera ''

Euryurus ''Euryurus'' is a genus of flat-backed millipedes in the family Euryuridae Euryuridae is a family of flat-backed millipedes in the order Polydesmida. There are at least 4 genera and about 14 described species in Euryuridae. Genera * ...

'', ''

Auturus ''Auturus'' is a genus of flat-backed millipedes in the family Euryuridae Euryuridae is a family of flat-backed millipedes in the order Polydesmida. There are at least 4 genera and about 14 described species in Euryuridae. Genera * ' ...

'', 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 Euryuridae is a family of flat-backed millipedes in the order Polydesmida. There are at least 4 genera and about 14 described species in Euryuridae. Genera * '' Auturus'' Chamberlin, 1942 * '' Euryurus'' Koch, 1847 * '' Eutheatus'' * '' ...

) by Hoffman in 1998 and allied closer to

Xystodesmidae 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, ...

. Similarly and concurrently, several neotropical genera previously placed in other subgroups of Platyrhacidae were removed and elevated to full family status: the

Aphelidesmidae Aphelidesmidae is a family of polydesmidan millipede 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 ...

References

External links

Photographs of Platyrhacidae
{{Taxonbar, from=Q6445204 Polydesmida Millipede families