Xystodesmidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

millipede Millipedes (originating from the Latin , "thousand", and , "foot") 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 derive ...

s in the

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Leptodesmidea within the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Polydesmida Polydesmida (from the Greek ''poly'' "many" and ''desmos'' "bond") is the largest order of millipedes, with more than 5,000 species, including all the millipedes reported to produce hydrogen cyanide (HCN). This order is also the most diverse of ...

(the "flat-backed" or "keeled" millipedes). The family Xystodesmidae was created by the American

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

Orator F. Cook in 1895 and named after the genus ''Xystodesmus''. This family includes more than 390 known species distributed among 62 genera. Many species, however, remain undescribed: 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.

Distribution

Millipedes in this family are found across the

northern hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, with peak diversity in the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain ...

, 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. Species in this family often have very small distributional areas, with many species only known from a single locality.

Description

Xystodemids are characterized by a relatively broad and compact body shape and one or more spines on the second leg-segments (prefemoral spines) in most species. Millipedes in this family range from 8 mm to 85 mm in length, with moderately convex bodies that taper toward both the front and especially the rear end. The antennae are slender and long. The paranota are normally large and prominent. Colors range from pitch black to pallid, often with vivid patterns. This family contains many colorful and distinctive species, including ''

Apheloria virginiensis ''Apheloria virginiensis'', the Kentucky flat millipede, is a large North American millipede. It gets its name from the yellow and orange markings on its back that give it a flattened appearance. It is reported to secrete cyanide compounds as a d ...

'' of the eastern U.S. and '' Harpaphe haydeniana'' of the western U.S. The Sierra luminous millipedes of the genus '' Motyxia'' exhibit the only known examples of

bioluminescence Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorgani ...

in the Polydesmida. Species of '' Apheloria'' and ''

Brachoria ''Brachoria'' is a genus of polydesmidan millipedes in the family Xystodesmidae inhabiting the Eastern United States. Also known as the Appalachian mimic millipedes, at least 30 species are known, with highest diversity in the Appalachian Mounta ...

'' in the Appalachians exhibit

Müllerian mimicry Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimicry, mimic each other's honest signal, honest aposematism, warning signals, to their mutuali ...

, in which unrelated species resemble one another where they co-occur. This family also includes the cave-dwelling genus '' Devillea'', notable for having more than the 20 segments (counting the collum as the first segment and the

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

as the last) usually found the Polydesmida. For example, in the species '' D. tuberculata'', adult females have 22 segments and adult males have 21, with a corresponding increase in the number of leg pairs (35 in adult females and 32 in adult males, excluding the gonopods). Some species in this genus also exhibit variation in segment number within the same sex, for example, in ''D. subterranea'', adult males can have as few as 19 segments or as many as 23. The species ''D. doderoi'' has the maximum number of segments recorded in this family (29, including the telson).

Classification

The family is divided into three subfamilies: the Melaphinae with around 10 species, the Parafontariinae with a dozen species in a single

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

, and the Xystodesminae, with many genera and species. Midoribaba yasude 02

Subfamily Melaphinae

Macellolophini *'' Macellolophus'' Melaphini *'' Melaphe'' *'' Ochridaphe''

Subfamily Parafontariinae

* '' Parafontaria''

Subfamily Xystodesminae

The subfamily Xystodesminae is subdivided into ten

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

,Hoffman, R. 1999. Checklist of the millipeds of North and Middle America. Virginia Museum of Natural History Special Publications 8, 1–553Marek, P., et al. (2014
''A Species Catalog of the Millipede Family Xystodesmidae (Diplopoda: Polydesmida)''.
Special Publication 17. Virginia Museum of Natural History. 140 p. each ending in the suffix "-ini", although taxonomist Richard Hoffman stated in his 1999 checklist: "I am by no means satisfied that this is the definitive arrangement, nor that the tribal divisions of the Xystodesminae are entirely satisfactory either." Apheloriini Hoffman, 1980 * '' Apheloria'' * '' Appalachioria'' * ''

'' * '' Brevigonus'' * '' Cheiropus'' * '' Cleptoria'' * '' Croatania'' * '' Deltotaria'' * '' Dixioria'' * '' Dynoria'' * '' Falloria'' * '' Furcillaria'' * '' Lyrranea'' * '' Prionogonus'' * '' Rudiloria'' * '' Sigmoria'' * '' Stelgipus'' Chonaphini Verhoeff, 1941 * '' Chonaphe'' * '' Metaxycheir'' * '' Montaphe'' * '' Selenocheir'' * '' Semionellus'' * '' Tubaphe'' Devilleini Brölemann, 1916 *'' Devillea'' Nannarini Hoffman, 1964 * '' Nannaria'' * '' Oenomaea'' Orophini Hoffman, 1964 *'' Kiulinga'' *'' Pamelaphe'' * '' Orophe'' Pachydesmini Hoffman, 1980 * '' Dicellarius'' * '' Pachydesmus'' * '' Thrinaxoria'' Rhysodesmini Brolemann, 1916 * '' Boraria'' * '' Cherokia'' * '' Erdelyia'' * '' Gyalostethus'' * '' Pleuroloma'' * '' Rhysodesmus'' * '' Stenodesmus'' * '' Caralinda'' * '' Gonoessa'' * '' Lourdesia'' * '' Parvulodesmus'' Sigmocheirini Causey, 1955 * '' Ochthocelata'' * '' Sigmocheir'' Xystocheirini Cook, 1904 * '' Anombrocheir'' * '' Motyxia'' * '' Parcipromus'' * '' Wamokia'' * '' Xystocheir'' Xystodesmini Hoffman, 1980 Harpaphe haydeniana 0446

* '' Harpaphe'' * '' Isaphe'' * '' Koreoaria'' * '' Levizonus'' * '' Riukiaria'' * '' Thrinaphe'' * '' Xystodesmus'' * '' Yaetakaria''

References

External links

* * {{Authority control Polydesmida Millipede families