Polydesmida

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Polydesmida
Apheloriavirginiensis.jpg
Apheloria virginiensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Myriapoda
Class: Diplopoda
Subclass: Chilognatha
Infraclass: Helminthomorpha
Subterclass: Eugnatha
Superorder: Merocheta
Cook, 1895
Order: Polydesmida
Leach, 1815 [1]
Suborders
Synonyms

Proterospermatophora Verhoeff, 1900

Polydesmida (from the Greek poly "many" and desmos "bond") is the largest order of millipedes, with more than 5,000 species, [2] [3] including all the millipedes reported to produce hydrogen cyanide (HCN). [4] This order is also the most diverse of the millipede orders in terms of morphology. [5] Millipedes in this order are found in all regions of the world other than Antarctica. [5]

Contents

Description

Members of the order Polydesmida are also known as flat-backed millipedes, because on most species, each body segment has wide lateral keels known as paranota. [6] [7] These keels are produced by the posterior half (metazonite) of each body ring behind the collum. [8] Polydesmids have no eyes, and vary in length from 1.4 to 134 mm. [5] Many of the larger species show bright coloration patterns which warn predators of their toxic secretions. [9]

Adults usually have 20 segments, [9] counting the collum as the first ring and the telson as the last ring. [10] [11] Juveniles have from 7 to 19 rings. [8] In species with the usual 20 segments, adult females have 31 pairs of legs, but in adult males, the eighth leg pair (the first leg pair of the 7th ring) is modified into a single pair of gonopods, leaving only 30 pairs of walking legs. [8] [10] [11]

Variation

Many species deviate from the typical body plan. One striking and unique deviation occurs in adult males of the species Aenigmopus alatus , which retain 31 pairs of walking legs and feature no gonopods. [10] [12] This millipede is the only species in the infraclass Helminthomorpha without gonopods. [5]

The most common deviation, however, is a reduction in the number of segments. Many species have only 19 segments (including the telson) as adults, including those in the genera Brachydesmus , Macrosternodesmus, and Bacillidesmus. [11] In these species, adult females have only 29 pairs of legs, and adult males have only 28 pairs of walking legs. [8] [10] In a few species, including Hexadesmus lateridens , Agenodesmus reticulatus , and Eutynellus flavior , adults have only 18 segments (including the telson), with a corresponding reduction in the number of leg pairs (27 in the adult female, 26 in the adult male, excluding the gonopods). [11] Still other species exhibit sexual dimorphism in segment number, for example, Prosopodesmus panporus (the usual 20 in adult females, but only 19 in adult males) and Doratodesmus pholeter (19 in adult females; 18 in adult males), with the expected number of leg pairs given the number of segments in each sex. [11] Even more unusual are two species, Ammodesmus congoensis and A. granum , in which adults in each sex can have 18 or 19 segments. [13] [14] [5]

Flat-backed Millipede (Polydesmida) Flat-backed Millipede (Polydesmida).jpg
Flat-backed Millipede (Polydesmida)

A few species deviate by having more than the usual number of segments, including those in the cave-dwelling genus Devillea . [11] [10] For example, in the species D. tuberculata , adult females have 22 segments and adult males have 21 (including the telson), with a corresponding increase in the number of leg pairs (35 in adult females and 32 in adult males, excluding the gonopods). [15] [11] [16] 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 (including the telson). [11] [16] The most extreme outlier in segment number among polydesmids, however, is a cave-dwelling species discovered in Brazil, Dobrodesmus mirabilis, with adult males found to have 40 segments (including the telson). [3] [10]

Development

Polydesmids grow and develop through a series of molts, 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 molting and the addition of segments and legs stop. [11] This mode of development, known as teloanamorphosis, distinguishes this order from most other orders of millipedes. Millipedes in other orders usually continue to molt as adults, developing through either euanamorphosis or hemianamorphosis. [11] [17]

Millipedes in this order typically develop through a series of eight stages, hatching with only 7 segments (including the telson) and 3 pairs of legs, then molting seven times. These eight stages feature 7, 9, 12, 15, 17, 18, 19, then finally 20 segments. The adults then reproduce and die without another molt. [11] Species with fewer than the usual 20 segments as adults go through the same stages observed in other polydesmids until reaching maturity, which occurs one molt earlier for 19 segments or two molts earlier for 18 segments. [11] [3] Species with more than the usual 20 segments are thought to add these extra segments through additional molts, adding one segment per molt. [11] [3]

Ecology

Polydesmids are very common in leaf litter, where they burrow by levering with the anterior end of the body. [7] These millipedes feed on decaying vegetation. Some species are prey for funnel-web spiders. [18]

Classification

The species of Polydesmida are variously classified into four suborders (names ending in "-idea"), and 29 families, the largest (numerically) including Paradoxosomatidae, Xystodesmidae, and Chelodesmidae. [19]

Dalodesmidea Hoffman, 1980. 2 families
Leptodesmidea Brölemann, 1916. 13 families
Paradoxosomatidea Daday, 1889. [lower-alpha 1] 1 family
Polydesmidea Pocock, 1887. 12 families

Related Research Articles

<span class="mw-page-title-main">Xystodesmidae</span> Family of millipedes

Xystodesmidae is a family of millipedes in the suborder Leptodesmidea within the order Polydesmida. The family Xystodesmidae was created by the American biologist 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.

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.

<span class="mw-page-title-main">Polyzoniida</span> Order of millipedes

Polyzoniida is an order of millipedes in the subterclass Colobognatha. This order contains three families and more than 70 described species. The species in this order are also known as camphor millipedes, because ozopore secretions in this order frequently have a strong camphor-like smell. Poison frogs in South America and Madagascar evidently obtain some of their poison from these millipedes.

<i>Orthomorpha</i> Genus of millipedes

Orthomorpha is a genus of millipedes in the family Paradoxosomatidae containing approximately 50 species distributed in Southeast Asia.

<span class="mw-page-title-main">Chordeumatida</span> Order of millipedes

Chordeumatida is a large order of millipedes containing more than 1,400 species. Also known as sausage millipedes, they are found nearly worldwide. Chordeumatida is the largest order in the superorder Nematophora, a group also known as spinning millipedes because their telsons feature spinnerets used to build nests of silk. These millipedes produce this silk to create chambers in which to molt or to lay their eggs.

<span class="mw-page-title-main">C. A. W. Jeekel</span> Dutch myriapodologist and entomologist

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.

<span class="mw-page-title-main">Platyrhacidae</span> Family of millipedes

Platyrhacidae is a family of polydesmidan millipedes distributed in Southeast Asia and tropical Central and South America.

<span class="mw-page-title-main">Haplodesmidae</span> Family of millipedes

Haplodesmidae is a family of millipedes in the order Polydesmida. This family includes about 70 species. Species occur in East Asia, Southeast Asia, and Oceania, although some species have been introduced to the New world tropics.

<span class="mw-page-title-main">Ammodesmidae</span> Family of millipedes

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. Although some authorities deem Fuhrmannodesmidae to be a junior synonym for Trichopolydesmidae, others still regard the taxonomic status of Fuhrmannodesmidae as valid. The family Fuhrmannodesmidae includes over 50 genera.

<span class="mw-page-title-main">Metopidiotrichidae</span> Family of millipedes

Metopidiotrichidae is a family of millipedes in the order Chordeumatida. This family includes more than 70 species. These millipedes are found in Indochina, Australia, and on Pacific islands from New Zealand to Japan.

<i>Brachydesmus</i> Genus of millipedes

Brachydesmus is a genus of millipedes belonging to the family Polydesmidae. The Czech zoologist Camill Heller first described this genus to contain the type species B. subterraneus. This genus now includes about 75 described species.

Chordeumatidae is a family of millipedes belonging to the order Chordeumatida. These millipedes range from 7 mm to 18 mm in length and are found in Europe. Adult millipedes in this family have either 28 or 30 segments. This family features distinctive sex-linked modifications to the legs in adults: In the adult female, a legless sternite replaces the third pair of legs, and in the adult male, five pairs of legs are modified in the gonopod complex. These modifications are more extensive than those found in other adult males in this order, which often have only two leg pairs modified into gonopods. With the more extensive modifications to the legs in this family, species with the usual 30 segments feature adult females with only 49 leg pairs and adult males with only 45 pairs of walking legs, and species with only 28 segments feature adult females with only 45 leg pairs and adult males with only 41 pairs of walking legs.

Agenodesmus is a genus of millipedes in the family Fuhrmannodesmidae, which some authorities consider a junior synonym of Trichopolydesmidae. This genus is notable for being among the very few genera in the order Polydesmida to feature adults with only 18 segments rather than the 20 segments usually found in this order. The genus Agenodesmus contains only two species, A. reticulatus and A. nullus. The type species A. reticulatus is notable as the first polydesmidan millipede discovered with only 18 segments in adults, the smallest number recorded in the order Polydesmida. Before the discovery of A. reticulatus, polydesmidans were known to have only 19 or 20 segments in adults.

Devillea is a genus of flat-backed millipedes in the family Xystodesmidae. These millipedes are rare and limited to caves. Species in this genus are found in Sardinia, Capri, and southern France in the Maritime Alps. These species are notable for featuring more than the 20 segments usually found in the order Polydesmida. This genus is one of only two genera in this order to feature these extra segments and the first such genus to be discovered.

Chamaesoma is a monotypic genus of millipede in the family Chamaesomatidae, and Chamaesoma broelemanni is the only species in this genus. This millipede is notable as one of only a few species in the order Chordeumatida with only 26 segments in adults, four fewer segments than typically found in adults this order. This species lives on the surface of the soil and is distributed across most of France and Luxembourg. The genus Chamaesoma and its only species were first described by the German zoologist Karl W. Verhoeff in 1913 based on type material found by the French zoologists Henri Brölemann and Henri Ribaut under wet leaf litter near St. Béat in the Pyrenees in France.

Devilliea tuberculata is a species of flat-backed millipedes in the family Xystodesmidae. Like other members of the genus Devillea, this species is limited to caves. This millipede has been found in several caves in the Alpes-Maritimes department of France. This species is notable as the first millipede in the order Polydesmida found to feature more than the 20 segments usually found in this order.

Agenodesmus reticulatus is a species of millipede in the family Fuhrmannodesmidae, which some authorities consider a junior synonym of Trichopolydesmidae. This millipede is among the very few species in the order Polydesmida to feature adults with only 18 segments rather than the 20 segments usually found in this order. This species is notable as the first polydesmidan millipede discovered with only 18 segments in adults, the smallest number recorded in the order Polydesmida. Before the discovery of A. reticulatus, polydesmidans were known to have only 19 or 20 segments in adults.

Prosopodesmus is a genus of flat-backed millipedes in the family Haplodesmidae. These millipedes are found primarily in Australia and southern Japan. This genus includes the species P. panporus, which is notable for exhibiting sexual dimorphism in segment number: Whereas adult females of this species feature the usual 20 segments usually observed in the order Polydesmida, the adult males of this species feature only 19 segments.

Prosopodesmus panporus is a species of flat-backed millipede in the family Haplodesmidae. Also known as the hothouse millipede, this species was first discovered in hothouses for tropical plants in England, where it is well established, but is probably native to Australia. This species features a unique distribution of ozopores, which appear on all segments with two pairs of legs. The species P. panporus is named for this complete series of ozopores and is the only species in the order Polydesmida with this distribution. This millipede is also notable for exhibiting sexual dimorphism in segment number: Whereas adult females of this species feature the 20 segments usually observed in the order Polydesmida, the adult males of this species feature only 19 segments.

References

  1. ↑ synonym: Strongylosomatidea Brölemann, 1916
  1. ↑ Robert Mesibov (2005). "A new genus of millipede (Diplopoda: Polydesmida: Dalodesmidae) from Tasmania with a pseudo-articulated gonopod telopodite" (PDF). Zootaxa . 1064: 39–49. doi:10.11646/zootaxa.1064.1.4.
  2. ↑ "Polydesmida Leach, 1815 | COL". www.catalogueoflife.org. Retrieved 2024-07-05.
  3. 1 2 3 4 Shear, William A.; Ferreira, Rodrigo Lopes; Iniesta, Luiz Felipe Moretti; Marek, Paul (2016-10-25). "A millipede missing link: Dobrodesmidae, a remarkable new polydesmidan millipede family from Brazil with supernumerary rings (Diplopoda, Polydesmida), and the establishment of a new suborder Dobrodesmidea". Zootaxa. 4178 (3): 371–390. doi:10.11646/zootaxa.4178.3.4. ISSN   1175-5334. PMID   27811714 – via ResearchGate.
  4. ↑ Thomas Eisner (2005). "Vinegaroons and other wizards". For Love of Insects. Harvard University Press. pp. 44–73. ISBN   978-0-674-01827-3.
  5. 1 2 3 4 5 Enghoff, Henrik; Golovatch, Sergei; Short, Megan; Stoev, Pavel; Wesener, Thomas (2015-01-01). "Diplopoda — taxonomic overview". Treatise on Zoology - Anatomy, Taxonomy, Biology. The Myriapoda, Volume 2: 363–453. doi:10.1163/9789004188273_017. ISBN   9789004188273.
  6. ↑ Henen, Derek; Brown, Jeff. Millipedes of Ohio (PDF). Ohio Division of Wildlife. pp. 3, 44.
  7. 1 2 Colin Little (1983). "Onychophorans and myriapods". The Colonisation of Land: Origins and Adaptations of Terrestrial Animals. Cambridge University Press. pp. 127–145. ISBN   978-0-521-25218-8.
  8. 1 2 3 4 Blower, J. Gordon (1985). Millipedes : keys and notes for the identification of the species. Linnean Society of London, Estuarine and Brackish-water Sciences Association. London: Published for the Linnean Society of London and the Estuarine and Brackish-Water Sciences Association by E.J. Brill. ISBN   90-04-07698-0. OCLC   13439686.
  9. 1 2 Shelley, Rowland M. (1999). "Centipedes and Millipedes with Emphasis on North American Fauna". The Kansas School Naturalist. 45 (3): 1–16. Archived from the original on 2016-11-12. Retrieved 2013-10-14.
  10. 1 2 3 4 5 6 Mesibov, Robert. "External Anatomy of Polydesmida: Body plans". myriapodology.org. Retrieved 2022-02-20.
  11. 1 2 3 4 5 6 7 8 9 10 11 12 13 Enghoff, Henrik; Dohle, Wolfgang; Blower, J. Gordon (1993). "Anamorphosis in Millipedes (Diplopoda) — The Present State of Knowledge with Some Developmental and Phylogenetic Considerations". Zoological Journal of the Linnean Society. 109 (2): 103–234. doi:10.1111/j.1096-3642.1993.tb00305.x.
  12. ↑ Loomis, H. F.; Hoffman, Richard L. (1962). "A remarkable new family of spined polydesmoid Diplopoda, including a species lacking gonopods in the male sex". Proceedings of the Biological Society of Washington. 75: 145–158. ISSN   0006-324X – via Biodiversity Heritage Library.
  13. ↑ VandenSpiegel, Didier; Golovatch, Sergei I. (2015). "A new millipede of the family Ammodesmidae found in central Africa (Diplopoda, Polydesmida)". ZooKeys (483): 1–7. doi: 10.3897/zookeys.483.9150 . PMC   4351444 . PMID   25755621.
  14. ↑ VandenSpiegel, Didier; Golovatch, Sergei (2012). "The millipede family Ammodesmidae (Diplopoda, Polydesmida) in western Africa". ZooKeys (221): 1–17. doi: 10.3897/zookeys.221.3739 . PMC   3487632 . PMID   23129978.
  15. ↑ Brölemann, H.-W. (1902). "Myriapodes Cavericoles". Annales de la Société Entomologique de France (in French). 71: 448–460 – via Biodiversity Heritage Library.
  16. 1 2 Minelli, Alessandro (2015-01-01). "Diplopoda — development". Treatise on Zoology - Anatomy, Taxonomy, Biology. The Myriapoda, Volume 2: 267–302. doi:10.1163/9789004188273_012. ISBN   9789004188273.
  17. ↑ Fusco, Giuseppe (December 2005). "Trunk segment numbers and sequential segmentation in myriapods". Evolution & Development. 7 (6): 608–617. doi:10.1111/j.1525-142X.2005.05064.x. PMID   16336414. S2CID   21401688 . Retrieved 25 August 2020.
  18. ↑ "Polydesmid Millipedes". The Australian Museum. Retrieved 2022-09-11.
  19. ↑ Shear, W (2011). Zhang, Z.-Q. (ed.). Class Diplopoda de Blainville in Gervais, 1844. In: Animal biodiversity : an outline of higher-level classification and survey of taxonomic richness (PDF). Zootaxa. pp. 159–164. ISBN   978-1-86977-850-7.
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