Polyxenida

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Polyxenida
Temporal range: Barremian–Present
Polyxenus.lagurus.1.jpg
Polyxenus lagurus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Myriapoda
Class: Diplopoda
Subclass: Penicillata
Latrielle, 1831
Order: Polyxenida
Verhoeff, 1934
Families
Synonyms

Subclass
Pselaphognatha Latzel, 1884
Schizocephala Verhoeff, 1926
Order
Ancyrotricha Cook, 1895

Contents

Segmentation of Polyxenida millipedes. From top to bottom: Lophoturus madecassus Other Lophoproctidae and Polyxenidae Condexenus biramipalpus and Phryssonotus brevicapensis Other Phryssonotus Polyxenida segmentation.jpg
Segmentation of Polyxenida millipedes. From top to bottom:
Lophoturus madecassus
Other Lophoproctidae and Polyxenidae
Condexenus biramipalpus and Phryssonotus brevicapensis
Other Phryssonotus

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. These features have inspired the common names bristly millipedes or pincushion millipedes. [1] [2] This order includes about 148 species in four families worldwide, which represent the only living members of the subclass Penicillata. [3] [4]

Description

Polyxenida differ from other millipedes in having a soft, non-calcified exoskeleton, unique tufts of bristles or setae, fewer legs (no more than 17 pairs), and an absence of copulatory appendages in males. [5] [3] Individuals are small, usually 1.5 to 4 millimeters (0.06 to 0.16 inches) long and not exceeding 7 millimeters (0.28 inches) long. [3] [4] Adults in most species have 13 pairs of legs, but in one species ( Lophoturus madecassus ), they have only 11 pairs of legs, and in one genus ( Phryssonotus ), they have 17 pairs of legs, except for one species (Phryssonotus brevicapensis) in which they (along with those in one other species, Condexenus biramipalpus ) have 15 pairs of legs. [3] [6]

Defense

Bristly millipedes lack the chemical defenses and hard exoskeleton of other millipedes. Instead, these millipedes employ a unique defense mechanism: Bristles at the rear end of these millipedes feature hooks and barbs. These distinctive barbed bristles can easily detach and become entangled in the limbs and mouth-parts of predatory insects, effectively immobilizing them. [7] [8]

Reproduction

Male Polyxenidans lack the modified sperm-transferring appendages (gonopods) found in most other millipede groups. Instead, sperm transfer is indirect: Males deposit spermatophores into webs that they construct. Females then find these spermatophores by following threads spun by the males and pick up the spermatophores with their genitalia. [9] [5]

At least two species reproduce asexually by way of parthenogenesis, wherein females lay eggs without mating and males are absent or rare. [3] [10] For example, studies of the common species Polyxenus lagurus have found males scarce or absent in parts of northeastern Europe. Authorities suspect that in these populations, this species reproduces by thelytoky, that is, parthenogenisis in which unfertilized females produce female offspring. [11]

Development

Millipedes in this order grow and develop through a series of molts, adding segments and legs until they reach a fixed number in the adult stage, which is the same in a given species. Adults continue to molt, but they do not add segments or legs. This mode of development is known as hemianamorphosis. [12]

The typical pattern in this order is observed in the common species Polyxenus lagurus. In this species, millipedes hatch with only 3 pairs of legs and 4 tergites, then develop through a series of seven molts and emerge as adults with 13 leg pairs and 10 tergites in the eighth stage. In this process, this millipede goes through stages with 3, 4, 5, 6, 8, 10, 12, and 13 leg pairs. Species in which adults have a different number of legs deviate from this common pattern. [12]

Classification

Phryssonotus brevicapensis (Synxenidae), a species from South Africa described in 2011 Phryssonotus brevicapensis.jpg
Phryssonotus brevicapensis (Synxenidae), a species from South Africa described in 2011

Polyxenida is the only living order of the subclass Penicillata, the basal subclass of millipedes. Penicillata is the sister group of all other living millipedes, which form the subclass Chilognatha. The subclass Chilognatha contains the infraclasses Pentazonia and Helminthomorpha. [13] [14]

In 2003, the order Polyxenida contained 159 valid species and/or subspecies. [4] At least eight new species have been described since 2010. [6] [15] [16]

Fossil history

The earliest representatives of Polyxenida are found in Lebanese amber from the Early Cretaceous period. The fossil records also include representatives found in Burmese amber, Baltic amber, and the Cretaceous amber of Haute-Provence in France. These fossils indicate that the families Polyxenidae and Synxenidae already existed in the Cretaceous period. [17]

Some authors place the extinct orders Arthropleurida and Eoarthropleurida (each represented by a single genus) within the Penicillata as a sister group to Polyxenida. [18] Others consider these extinct orders to be a sister group to Penicillata. Still others deem these extinct orders to be a sister group to the subclass Chilognatha instead. [19]

Related Research Articles

<span class="mw-page-title-main">Millipede</span> Class of arthropods

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.

<span class="mw-page-title-main">Chilognatha</span> Subclass of millipedes

Chilognatha is a subclass of the class Diplopoda, which includes the vast majority of extant millipedes, about 12,000 species.

<span class="mw-page-title-main">Arthropleuridea</span> Extinct subclass of millipedes

Arthropleuridea is an extinct subclass of myriapod arthropods that flourished during the Carboniferous period, having first arisen 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.

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

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.

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

Polydesmida 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 millipede orders in terms of morphology. Millipedes in this order are found in all regions of the world other than Antarctica.

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

Polyxenidae is a family of millipedes in the order Polyxenida containing approximately 47 species in 19 genera. All adults in this family have 13 pairs of legs.

<i>Polyxenus lagurus</i> Species of millipede

Polyxenus lagurus, known as the bristly millipede is a species of millipede found in many areas of Europe and North America. It is covered with detachable bristles that have the ability to entangle ants and spiders that attack the animal.

<i>Polyxenus</i> (millipede) Genus of millipedes

Polyxenus is a genus of millipede in the order Polyxenida, containing at least 30 valid species as of 2012.

<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.

<i>Siphoniulus</i> Genus of millipedes

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.

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

Synxenidae is a family of bristle millipedes (Polyxenida). Three genera and around 10 species are known. Adult synxenids possess 15 or 17 pairs of legs, with the last two pair modified for small jumps. Adults in most species in this family have 17 pairs of legs, but in two species, they have only 15 pairs of legs.

Condexenus is a genus of bristle millipede containing the sole species Condexenus biramipalpus known from Namibia. Individuals are up to 3 mm long, and adults possess 11 body segments and 15 pairs of legs.

<i>Phryssonotus</i> Genus of millipedes

Phryssonotus is a genus of bristle millipedes containing around nine extant species. Species are characterized by the possession of dark, rear-projecting scale-shaped bristles (trichomes) on the tergites; all other bristles are long and hairlike. Adults in this genus have 17 pairs of legs, except for the species Phryssonotus brevicapensis, in which they have only 15 pairs of legs.

Bollmania is a genus of millipedes with around six species occurring from Central through East Asia, including Iran, Pakistan, Tajikistan, and China. The genus was established by entomologist Filippo Silvestri in 1896, and is named in honor of Charles Harvey Bollman. Bollmania is the sole genus of the family Caspiopetalidae.

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

Lophoproctidae is a family of millipedes in the order Polyxenida containing approximately 65 species in 6 genera.

<i>Lophoturus</i> Genus of millipedes


Lophoturus is a genus of millipedes belonging to the family Lophoproctidae. Species described after year 2000 include two from Queensland, Australia, three from Christmas Island, Australia, and three from the Caribbean and northern South America.

<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.

Termitodesmidae is a family of millipedes belonging to the order Glomeridesmida. These millipedes are found in India, Sri Lanka, and Vietnam. The five known species in this family are notable in that they are found only in termite mounds. Termitodesmidae is the only myriapod family known to depend on insects in such a commensal relationship.

Monographis is a terrestrial genus of millipede in the family Polyxenidae comprising 10 species.

References

  1. ↑ Henen, Derek; Brown, Jeff. Millipedes of Ohio (PDF). Ohio Division of Wildlife. pp. 3, 16–17.
  2. ↑ "Order Polyxenida - Bristly Millipedes". bugguide.net. Retrieved 2024-07-23.
  3. 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.
  4. 1 2 3 Nguyen Duy-Jacquemin, M.; J.-J. Geoffroy (2003). "A revised comprehensive checklist, relational database, and taxonomic system of reference for the bristly millipedes of the world (Diplopoda, Polyxenida)". African Invertebrates. 44 (1): 89–101.
  5. 1 2 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.
  6. 1 2 3 Nguyen Duy - Jacquemin, Monique; Uys, Charmaine; Geoffroy, Jean-Jacques (2011). "Two remarkable new species of Penicillata (Diplopoda, Polyxenida) from Table Mountain National Park (Cape Town, South Africa)". ZooKeys (156): 85–103. doi: 10.3897/zookeys.156.2211 . PMC   3253573 . PMID   22303097.
  7. ↑ Shelley, Rowland M. "The Myriapoda (Millipedes, Centipedes) Featuring the North American Fauna". Archived from the original on 30 October 2013. Retrieved 30 October 2013.
  8. ↑ Eisner, T; Eisner, M; Deyrup, M (1996). "Millipede defense: use of detachable bristles to entangle ants". Proceedings of the National Academy of Sciences of the United States of America. 93 (20): 10848–51. Bibcode:1996PNAS...9310848E. doi: 10.1073/pnas.93.20.10848 . PMC   38244 . PMID   8855269.
  9. ↑ 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 2013-10-12.
  10. ↑ Barnes, Robert D. (1987). "15. The myriapods". Invertebrate zoology (5th ed.). Philadelphia: Saunders College Pub. pp. 674–683.
  11. ↑ Enghoff, Henrik (1976). "Morphological comparison of bisexual and parthenogenetic Polyxenus lagurus (Linne, 1758) (Diplopoda Polyxenidae) in Denmark and Southern Sweden, with notes on taxonomy, distribution and ecology" (PDF). Entomologiske Meddelelser. 44: 161–182.
  12. 1 2 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.
  13. ↑ Sierwald, Petra; Bond, Jason E. (2007). "Current Status of the Myriapod Class Diplopoda (Millipedes): Taxonomic Diversity and Phylogeny". Annual Review of Entomology. 52 (1): 401–420. doi:10.1146/annurev.ento.52.111805.090210. PMID   17163800.
  14. ↑ Shear, W (2011). "Class Diplopoda de Blainville in Gervais, 1844. In: Zhang, Z.-Q.(ed.) Animal biodiversity : an outline of higher-level classification and survey of taxonomic richness" (PDF). Zootaxa. 3148: 159–164. doi:10.11646/zootaxa.3148.1.32.
  15. ↑ Short, Megan; Huynh, Cuong (2011). "The genus Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) in Australia". ZooKeys (156): 105–122. doi: 10.3897/zookeys.156.2168 . PMC   3253574 . PMID   22303098.
  16. ↑ Short, Megan; Huynh, Cuong (2013). "Four new species of Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) from Australia". ZooKeys (278): 75–90. doi: 10.3897/zookeys.278.4765 . PMC   3677348 . PMID   23794829.
  17. ↑ Duy-Jacquemin, MN; Azar, D (2004). "The oldest records of Polyxenida (Myriapoda, Diplopoda): New discoveries from the Cretaceous ambers of Lebanon and France". Geodiversitas. 26 (4): 631–641.
  18. ↑ Kraus, O; C. Brauckman (2003). "Fossil giants and surviving dwarfs. Arthropleurida and Pselaphognatha (Ateolocerata, Diplopoda): characters, phylogenetic relationships and construction". Verh. Naturwiss. Ver. Hamburg. 40 (5): 5–50.
  19. ↑ Shear, William A.; Edgecombe, Gregory D. (2010). "The geological record and phylogeny of the Myriapoda". Arthropod Structure & Development. 39 (2–3): 174–190. doi:10.1016/j.asd.2009.11.002. PMID   19944188.
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