Symphyla

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Symphyla
Temporal range: 99–0  Ma
Scutigerella immaculata male.jpg
Scutigerella immaculata
Symphyla (unknown species).jpg
Unidentified species
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Myriapoda
Class: Symphyla
Ryder, 1880
Families

Scutigerellidae
Scolopendrellidae

Symphylans, also known as garden centipedes or pseudocentipedes, are soil-dwelling arthropods of the class Symphyla in the subphylum Myriapoda. Symphylans resemble centipedes, but are very small, non-venomous, and only distantly related to both centipedes and millipedes. They can move rapidly through the pores between soil particles, and are typically found from the surface down to a depth of about 50 centimetres (20 in). They consume decaying vegetation, but can do considerable harm in an agricultural setting by consuming seeds, roots, and root hairs in cultivated soil.

Contents

Juveniles have six pairs of legs, but over a lifetime of several years, they add an additional pair at each moult so an adult instar has twelve pairs of legs. [1] Symphylans lack eyes. Their long antennae serve as sense organs. They have several features linking them to early insects, such as a labium (fused second maxillae), an identical number of head segments and certain features of their legs. [2]

About 200 species are known worldwide. [3]

Description

Symphyla are small, cryptic myriapods without eyes and without pigment. [4] The body is soft and generally 2 to 10 millimetres (0.08 to 0.4 in) long, divided into two body regions: head and trunk. An exceptional size is reached in Hanseniella magna , which attains lengths of 25 to 30 mm (1.0 to 1.2 in). [5]

The head has long, segmented antennae, a postantennal organ, three pairs of mouthparts: mandibles, the long first maxillae, and the second pair of maxillae which are fused to form the lower lip or labium of the mouth. Disc-like organs of Tömösváry, which probably sense vibrations, are attached to the base of the antennae, as they are in centipedes. [6]

The trunk comprises 15–24 segments, which are protected by overlapping dorsal plates. Ten or twelve segments bear legs. The first segment is large and usually provided with a pair of legs, the last segment is slender, lacks legs, and possesses a pair of cerci. Immature individuals have six pairs of legs on hatching. Each pair of legs is associated with an eversible structure, called a "coxal sac", that helps the animal absorb moisture, and a small stylus that may be sensory in function. Similar structures are found in the most primitive insects. [6]

Symphyla are rapid runners. They are primarily herbivores and detritus feeders living deep in the soil, under stones, in decaying wood, and in other moist places. The garden symphylan, Scutigerella immaculata can be a pest of crops. A species of Hanseniella has been recorded as a pest of sugar cane and pineapples in Queensland. [7] [8] A few species are found in trees [9] [10] and in caves. [11] A species of Symphylella has been shown to be predominantly predatory, [12] and some species are saprophagous.

Life stages of symphylans: eggs, juvenile, and adult Scutigerella immaculata Garden centipede (Scutigerella immaculata) life stages.jpg
Life stages of symphylans: eggs, juvenile, and adult Scutigerella immaculata

Symphylans breathe through a pair of spiracles on the sides of the head. These are connected to a system of tracheae that branch through the head and the first three segments of the body only. [6]

The genital openings are located on the fourth body segment, but the animals do not copulate. Instead, the male deposits 150 to 450 packages of sperm, or spermatophores, on small stalks. The female then picks these up in her mouth, which contains special pouches for storing the sperm. She then lays her eggs, and attaches them to the sides of crevices or to moss or lichen with her mouth, smearing the sperm over them as she does so. The eggs are laid in groups of eight to twelve. [6]

Symphylans have been reported as living up to four years, and moult throughout their life. [6]

Fossil record and evolution

The symphylan fossil record is poorly known, with only five species recorded, all placed in living genera. The oldest records of both families are found in Burmese amber from the middle Cretaceous, approximately 99 million years ago. As a result, both families are thought to have diverged before the end of the Mesozoic Era. [13] [14] [15]

Despite their common name, morphological studies commonly place symphylans as more closely related to millipedes and pauropods than the centipedes, in the clade Progoneata. [16] [17] Molecular studies have shown conflicting results, with some supporting the Progoneata clade, others aligning symphylans with centipedes or other arthropods, although some are weakly supported. [18] [16]

Related Research Articles

Protura Order of arthropods

The Protura, or proturans, and sometimes nicknamed coneheads, are very small, soil-dwelling animals, so inconspicuous they were not noticed until the 20th century. The Protura constitute an order of hexapods that were previously regarded as insects, and sometimes treated as a class in their own right.

Millipede 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 being 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 ball. Although the name "millipede" derives from the Latin for "thousand feet", no known species has 1,000; the record of 750 legs belongs to Illacme plenipes. 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.

Centipede

Centipedes are predatory arthropods belonging to the class Chilopoda of the subphylum Myriapoda, an arthropod group which also includes millipedes and other multi-legged creatures. Centipedes are elongated metameric creatures with one pair of legs per body segment. Most centipedes are generally venomous and can inflict painful bites, injecting their venom through pincer-like appendages known as forcipules. Despite the name, centipedes can have a varying number of legs, ranging from 30 to 354. Centipedes always have an odd number of pairs of legs. Therefore, no centipede has exactly 100 legs. Like spiders and scorpions, centipedes are predominantly carnivorous.

Pauropoda

Pauropods are small, pale, millipede-like arthropods. Around 830 species in twelve families are found worldwide, living in soil and leaf mould. They look rather like centipedes, but are probably the sister group to millipedes.

<i>Scutigera coleoptrata</i>

Scutigera coleoptrata is a small, typically yellowish-grey centipede with up to 15 pairs of long legs. Originating in the Mediterranean region, the species has spread to other parts of the world, where it can live in human homes, thus gaining the name house centipede. It is an insectivore; it kills and eats other arthropods, such as insects and arachnids.

Myriapoda

Myriapoda is a subphylum of arthropods containing millipedes, centipedes, and others. The group contains over 16,000 species, most of which are terrestrial. Although their name suggests they have myriad (10,000) legs, myriapods range from having up to 750 legs to having fewer than ten legs.

Cercus

Cerci are paired appendages on the rear-most segments of many arthropods, including insects and symphylans. Many forms of cerci serve as sensory organs, but some serve as pinching weapons or as organs of copulation. In many insects, they simply may be functionless vestigial structures.

Appendage External body part or natural prolongation, that protrudes from an organisms body

In invertebrate biology, an appendage is an external body part, or natural prolongation, that protrudes from an organism's body. An appendage is any of the homologous body parts that may extend from a body segment. These include antennae, mouthparts, gills, walking legs (pereiopods), swimming legs (pleopods), sexual organs (gonopods), and parts of the tail (uropods). Typically, each body segment carries one pair of appendages.

Entognatha Class of arthropods

The Entognatha are a class of wingless and ametabolous arthropods, which, together with the insects, makes up the subphylum Hexapoda. Their mouthparts are entognathous, meaning that they are retracted within the head. Entognatha are apterous, meaning that they lack wings. The class contains three orders: Collembola (springtails), Diplura (“two-tail”) and Protura (“first-tail”), and over 5000 known species. These three groups were historically united with the now-obsolete order Thysanura to form the class Apterygota, but it has since been recognized that the hexapodous condition of these animals has evolved independently from that of insects, and independently within each order. The orders may not be closely related, and Entognatha is now considered to be a polyphyletic group.

Arthropod mouthparts

The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts. In general, arthropods have mouthparts for cutting, chewing, piercing, sucking, shredding, siphoning, and filtering. This article outlines the basic elements of four arthropod groups: insects, myriapods, crustaceans and chelicerates. Insects are used as the model, with the novel mouthparts of the other groups introduced in turn. Insects are not, however, the ancestral form of the other arthropods discussed here.

Mandible (arthropod mouthpart) Pair of mouthparts used either for biting or cutting and holding food

The mandible of an arthropod is a pair of mouthparts used either for biting or cutting and holding food. Mandibles are often simply referred to as jaws. Mandibles are present in the extant subphyla Myriapoda, Crustacea and Hexapoda. These groups make up the clade Mandibulata, which is currently believed to be the sister group to the rest of arthropods, the clade Arachnomorpha.

Maxilla (arthropod mouthpart)

In arthropods, the maxillae are paired structures present on the head as mouthparts in members of the clade Mandibulata, used for tasting and manipulating food. Embryologically, the maxillae are derived from the 4th and 5th segment of the head and the maxillary palps; segmented appendages extending from the base of the maxilla represent the former leg of those respective segments. In most cases, two pairs of maxillae are present and in different arthropod groups the two pairs of maxillae have been variously modified. In crustaceans, the first pair are called maxillulae.

Glomerida

Glomerida is an order of pill-millipedes found primarily in the Northern Hemisphere. 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.

Arthropod Phylum of invertebrates with jointed exoskeletons

An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora.

Hexapoda Subphylum of arthropods

The subphylum Hexapoda constitutes the largest number of species of arthropods and includes the insects as well as three much smaller groups of wingless arthropods: Collembola, Protura, and Diplura. The Collembola are very abundant in terrestrial environments. Hexapods are named for their most distinctive feature: a consolidated thorax with three pairs of legs. Most other arthropods have more than three pairs of legs.

<i>Siphoniulus</i>

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.

Dendrothereua is a genus of house centipedes in the family Scutigeridae. There are at least three described species in Dendrothereua, found in the southern United States and the Neotropics.

Scutigerellidae

Scutigerellidae is a family of symphylans. There are at least three genera and 30 described species in Scutigerellidae. The oldest described species of the family are members of the extant genera Hanseniella and Scutigerella from Eocene aged Baltic amber, undescribed specimens of the family are known from the Cenomanian aged Burmese amber of Myanmar.

<i>Scutigerella immaculata</i>

Scutigerella immaculata, commonly known as the garden symphylan or glasshouse symphylid, is a species of myriapod in the family Scutigerellidae. It may have originated in Europe but now has a cosmopolitan distribution and can be a pest of crops.

References

  1. "Garden Symphylans". Integrated Pest Management on Peppermint-IPMP3.0. Oregon State University . Retrieved 2007-07-02.
  2. C. Gillott (2005). Entomology, 3rd Edition. Springer Verlag. ISBN   978-1-4020-3182-3.
  3. A. D. Chapman (2005). Numbers of Living Species in Australia and the World (PDF). Department of the Environment and Heritage. ISBN   978-0-642-56850-2.
  4. Penny Greenslade (2002-03-31). "Class: Symphyla". Australian Faunal Directory . Australian National University.
  5. Minelli, Alessandro; Sergei I. Golovatch (2001). "Myriapods" (PDF). In Simon A. Levin (ed.). Encyclopedia of Biodiversity. pp. 291–303. ISBN   978-0122268656. Archived from the original (PDF) on 2014-02-21.
  6. 1 2 3 4 5 Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 817–818. ISBN   978-0-03-056747-6.
  7. H. Boyle (1981). "Symphyla control in young plant cane". Cane Growers' Quarterly Bulletin. 44: 115–116.
  8. D. A. H. Murray & D. Smith (1983). "Effect of Symphyla, Hanseniella sp., on establishment of pineappes in south-east Queensland". Queensland Journal of Agricultural Science. 40: 121–123.
  9. J. Adis & U. Scheller (1984). "On the natural history and ecology of Hanseniella arborea (Myriapoda, Symphyla, Scutigerellidae), a migrating symphylan from an Amazonian black-water inundation forest". Pedobiologia. 27: 35–41.
  10. S. Clark & P. Greenslade (1996). "Review of Tasmanian Hanseniella Bagnall (Symphyla: Scutigerellidae)". Invertebrate Taxonomy. 10 (1): 189–212. doi:10.1071/IT9960189.
  11. Eberhard, S.M. & Spate (1995). "Cave Invertebrate Survey; toward an atlas of NSW Cave Fauna". A Report Prepared Under NSW Heritage Assistance Program NEP. 94: 765.
  12. D. E. Walter, J. C. Moore & S. Loring (1989). "Symphylella sp. (Symphyla: Scolopendrellidae predators of arthropods and nematodes in grassland soils". Pedobiologia. 33: 113–116.
  13. Moritz, Leif; Wesener, Thomas (2017). "Symphylella patrickmuelleri sp. nov. (Myriapoda: Symphyla): The oldest known Symphyla and first fossil record of Scolopendrellidae from Cretaceous Burmese amber". Cretaceous Research. 84: 258–263. doi:10.1016/j.cretres.2017.11.018.
  14. Minelli, Alessandro (2011). Treatise on Zoology - Anatomy, Taxonomy, Biology. The Myriapoda. BRILL. p. 459. ISBN   978-90-04-15611-1.
  15. Wesener, Thomas; Moritz, Leif (2018-12-17). "Checklist of the Myriapoda in Cretaceous Burmese amber and a correction of the Myriapoda identified by Zhang (2017)". Check List. 14(6): 1131–1140. doi: 10.15560/14.6.1131 . ISSN   1809-127X.
  16. 1 2 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.
  17. Gai, Yonghua; Song, Daxiang; Sun, Hongying; Yang, Qun; Zhou, Kaiya (2008). "The complete mitochondrial genome of Symphylella sp. (Myriapoda: Symphyla): Extensive gene order rearrangement and evidence in favor of Progoneata". Molecular Phylogenetics and Evolution. 49 (2): 574–585. doi:10.1016/j.ympev.2008.08.010. PMID   18782622.
  18. Regier, Jerome C.; Wilson, Heather M.; Shultz, Jeffrey W. (2005). "Phylogenetic analysis of Myriapoda using three nuclear protein-coding genes". Molecular Phylogenetics and Evolution. 34 (1): 147–158. doi:10.1016/j.ympev.2004.09.005. PMID   15579388.

Further reading