Odonata

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Odonata
Temporal range: Early Permian–Recent[1]
Tau emerald Dec10.jpg
Tau emerald (Hemicordulia tau) dragonfly
Scientific classification e
Kingdom: Animalia
Phylum: Euarthropoda
Class: Insecta
Subclass: Pterygota
Division: Palaeoptera
Superorder: Odonatoptera
(unranked): Holodonata
Order: Odonata
Fabricius, 1793[2]
Suborders

Epiprocta (dragonflies)
Zygoptera (damselflies)
and see text

Odonata is an order of carnivorous insects, encompassing the dragonflies (Anisoptera) and the damselflies (Zygoptera). The Odonata form a clade, which has existed since the Permian.[3][1]

Dragonflies are generally larger, and perch with their wings held out to the sides; damselflies have slender bodies, and hold their wings over the body at rest.

Etymology and terminology[edit]

Fabricius coined the term Odonata from the Ancient Greek ὀδών odṓn (Ionic form of ὀδούς odoús) 'tooth' apparently because they have teeth on their mandibles, even though most insects also have toothed mandibles.[4]

The word dragonfly is also sometimes used to refer to all Odonata, but odonate is a more correct English name for the group as a whole.[5] Odonata enthusiasts avoid ambiguity by using the term true dragonfly,[6] or simply Anisopteran,[7] when referring to just the Anisoptera. The term Warriorfly has also been proposed.[8] Some 5,900 species have been described in this order.[9]

Systematics and taxonomy[edit]

This order has traditionally been grouped together with the mayflies and several extinct orders in a group called the "Paleoptera", but this grouping might be paraphyletic. What they do share with mayflies is the nature of how the wings are articulated and held in rest (see insect flight for a detailed discussion).

In some treatments,[10] the Odonata are understood in an expanded sense, essentially synonymous with the superorder Odonatoptera but not including the prehistoric Protodonata. In this approach, instead of Odonatoptera, the term Odonatoidea is used. The systematics of the "Palaeoptera" are by no means resolved; what can be said however is that regardless of whether they are called "Odonatoidea" or "Odonatoptera", the Odonata and their extinct relatives do form a clade.[11]

The Anisoptera was long treated as a suborder, with a third suborder, the "Anisozygoptera" (ancient dragonflies). However, the combined suborder Epiprocta (in which Anisoptera is an infraorder) was proposed when it was found that the "Anisozygoptera" was paraphyletic, composed of mostly extinct offshoots of dragonfly evolution. The four living species placed in that group are (in this treatment) in the infraorder Epiophlebioptera, whereas the fossil taxa that were formerly there are now dispersed about the Odonatoptera (or Odonata sensu lato).[12] World Odonata List considers Anisoptera as a suborder along with Zygoptera and Anisozygoptera as well-understood and widely preferred terms.[13][14]

Tarsophlebiidae is a prehistoric family of Odonatoptera that can be considered either a basal lineage of Odonata or their immediate sister taxon.

with prey

The phylogenetic tree of the orders and suborders of odonates according to Bechly (2002):[15]

Odonatoptera

Geroptera (only Eugeropteridae)

Holodonata

Eomeganisoptera (only "Erasipteridae")

Meganisoptera

Campylopterodea (only Campylopteridae)

Protanisoptera

Triadotypomorpha (only Triadotypidae)

Triadophlebiomorpha

Protozygoptera

Archizygoptera

Tarsophlebioptera (only Tarsophlebiidae)

Odonata

Zygoptera (damselflies)

Sieblosiidae

Epiprocta (= Epiproctophora)

Isophlebioptera

Anisozygoptera (= Epiophlebioptera, restricted to Recent Epiophlebiidae)

Heterophlebioptera

Stenophlebioptera

Anisoptera ([true] dragonflies)

External morphology[edit]

Size[edit]

The largest living odonate is the giant Central American helicopter damselfly Megaloprepus coerulatus (Zygoptera: Pseudostigmatidae) with a wing span of 191 mm. The heaviest living odonates are Tetracanthagyna plagiata (Anisoptera: Aeshnidae) with a wing span of 165 mm, and Petalura ingentissima (Anisoptera: Petaluridae) with a body length of 117 mm (some sources 125 mm) and wing span of 160 mm. The longest extant odonate is the Neotropical helicopter damselfly Mecistogaster linearis (Zygoptera: Pseudostigmatidae) with a body length of 135 mm. Sometimes the giant Hawaiian darner Anax strenuus (Anisoptera: Aeshnidae) is claimed to be the largest living odonate with an alleged wing span of 190 mm, but this seems to be rather a myth as only 152 mm are scientifically documented.

Odonata and their ancestors come from one of the oldest winged insect groups.  The fossils of odonates and their cousins Paleozoic "giant dragonflies" like Meganeuropsis permiana from the Permian of North America with up to 71 cm wing span[16][17] and 43 cm body length have been the largest insects of all times and belonged to the order Meganisoptera, the griffinflies, related to odonates but not part of the modern order Odonata in the restricted sense have one of the most complete records going back 319 million years ago.[18]

The smallest living dragonfly is Nannophya pygmaea (Anisoptera: Libellulidae) from east Asia, which a body length of 15 mm and a wing span of 20 mm, and the smallest damselflies (and smallest odonates of all times) are species of the genus Agriocnemis (Zygoptera: Coenagrionidae) with a wing span of only 17–18 mm.

Description[edit]

Male blue ringtail (Austrolestes annulosus), a damselfly (Zygoptera: Lestidae)
Dragonfly (top) and damselfly (bottom) wing shape and venation

These insects characteristically have large rounded heads covered mostly by well-developed, compound eyes, legs that facilitate catching prey (other insects) in flight, two pairs of long, transparent wings that move independently, and elongated abdomens. They have three ocelli and short antennae. The mouthparts are on the underside of the head and include simple chewing mandibles in the adult.[19]

Flight in the Odonata is direct, with flight muscles attaching directly to the wings; rather than indirect, with flight muscles attaching to the thorax, as is found in the Neoptera. This allows active control of the amplitude, frequency, angle of attack, camber and twist of each of the four wings entirely independently.[20]

In most families there is a structure on the leading edge near the tip of the wing called the pterostigma. This is a thickened, hemolymph–filled and often colorful area bounded by veins. The functions of the pterostigma are not fully known, but it most probably has an aerodynamic effect[21] and may also have a visual function. More mass at the end of the wing may also reduce the energy needed to move the wings up and down. The right combination of wing stiffness and wing mass could reduce the energy consumption of flying. A pterostigma is also found among other insects, such as bees.

The nymphs have stockier, shorter, bodies than the adults. In addition to lacking wings, their eyes are smaller, their antennae longer, and their heads are less mobile than in the adult. Their mouthparts are modified, with the labium being adapted into a unique prehensile organ for grasping prey. Damselfly nymphs breathe through external gills on the abdomen, while dragonfly nymphs respire through an organ in their rectum.[19]

Damselflies in copulatory "wheel"

Although generally fairly similar, dragonflies differ from damselflies in several, easily recognizable traits. Dragonflies are strong fliers with fairly robust bodies and at rest hold their wings either out to the side or out and downward (or even somewhat forward). Damselflies tend to be less robust, even rather weak appearing in flight, and when at rest most species hold their wings folded back over the abdomen (see photograph below, left). Dragonfly eyes occupy much of the animal's head, touching (or nearly touching) each other across the face. In damselflies, there is typically a gap in between the eyes.

Ecology and life cycle[edit]

Ovipositing flight of two azure damselfly couples (Coenagrion puella)

Odonates are aquatic or semi-aquatic as juveniles. Thus, adults are most often seen near bodies of water and are frequently described as aquatic insects. However, many species range far from water. They are carnivorous (or more specifically insectivorous) throughout their life, mostly feeding on smaller insects.

Male Odonata have complex genitalia, different from those found in other insects. These include grasping cerci for holding the female and a secondary set of copulatory organs on the abdomen in which the sperm are held after being produced by the primary genitals. To mate, the male grasps the female by the thorax or head and bends her abdomen so that her own genitalia can be grasped by the copulatory organs holding the sperm.[19] Male odonates have a copulatory organ on the ventral side of abdominal segment 2 in which they store spermatozoa; they mate by holding the female's head (Anisoptera) or thorax (Zygoptera) with claspers located at the tip of the male abdomen; the female bends her abdomen forward to touch the male organ and receive sperm. This is called the "wheel" position.

Eggs are laid in water or on vegetation near water or wet places, and hatch to produce pronymphs which live off the nutrients that were in the egg. They then develop into instars with approximately 9–14 molts that are (in most species) voracious predators on other aquatic organisms, including small fishes. The nymphs grow and molt, usually in dusk or dawn, into the flying teneral immature adults, whose color is not yet developed. These insects later transform into reproductive adults.

Odonates can act as bioindicators of water quality in rivers because they rely on high quality water for proper development in early life. Since their diet consists entirely of insects, odonate density is directly proportional to the population of prey, and their abundance indicates the abundance of prey in the examined ecosystem.[22] Species richness of vascular plants has also been positively correlated with the species richness of dragonflies in a given habitat. This means that in a location such as a lake, if one finds a wide variety of odonates, then a similarly wide variety of plants should also be present. This correlation is not common to all bioindicators, as some may act as indicators for a different environmental factor, such as the pool frog acting as a bioindicator of water quality due to its high quantity of time spent in and around water.[23]

In addition, odonates are very sensitive to changes to average temperature. Many species have moved to higher elevations and latitudes as global temperature rises and habitats dry out.  Changes to the life cycle have been recorded with increased development of the instar stages and smaller adult body size as the average temperature increases.  As the territory of many species starts to overlap, the rate hybridization of species that normally do not come in contact is increasing.[18]  If global climate change continues many members of Odonata will start to disappear. Because odonates are such and old order and have such a complete fossil record they are a ideal species to study insect evolution and adaptation.  For example, they are one of the first insects to develop flight and it is likely that this trait only evolved once in insects, looking at how flight works in odonates the rest of flight can be mapped out.[18]

See also[edit]

Lists of Odonata species of Australia - Britain - India - Ireland - South Africa - Sri Lanka - Taiwan

References[edit]

  1. ^ a b Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed. Oxford University Press. p. 320. ISBN 978-0-19-510033-4.CS1 maint: Multiple names: authors list (link)
  2. ^ Fabricius, Johann Christian (1793). Entomologia Systematica Emendata et Aucta. Secundum, Classes, Ordines, Genera, Species, adjectis synonimis, locis, observationibus, descriptionibus (in Latin). Hafniae : impensis Christ. Gottl. Proft. pp. 519 [373]. doi:10.3931/e-rara-26792 – via e-rara.ch.
  3. ^ Suhling, F.; Sahlén, G.; Gorb, S.; Kalkman, V.J.; Dijkstra, K-D.B.; van Tol, J. (2015). "Order Odonata". In Thorp, James; Rogers, D. Christopher (eds.). Ecology and general biology. Thorp and Covich's Freshwater Invertebrates (4 ed.). Academic Press. pp. 893–932. ISBN 9780123850263.
  4. ^ Mickel, Clarence E. (1934). "The significance of the dragonfly name "Odonata"". Annals of the Entomological Society of America. 27 (3): 411–414. doi:10.1093/aesa/27.3.411.
  5. ^ "Odonate". Merriam-Webster Dictionary.
  6. ^ Field guide to lower aquarium animals. Cranbrook Institute of Science. 1939.
  7. ^ Orr, A. G. (2005). Dragonflies of Peninsular Malaysia and Singapore. ISBN 978-983-812-103-3.
  8. ^ Philip S. Corbet & Stephen J. Brook (2008). Dragonflies. London: Collins. ISBN 978-0-00-715169-1.
  9. ^ Zhang, Z.-Q. (2011). "Phylum Arthropoda von Siebold, 1848 In: Zhang, Z.-Q. (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness" (PDF). Zootaxa. 3148: 99–103.
  10. ^ E.g. Trueman & Rowe (2008)
  11. ^ Trueman [2008]
  12. ^ Lohmann (1996), Rehn (2003)
  13. ^ Martin Schorr; Dennis Paulson. "World Odonata List". University of Puget Sound. Retrieved 12 Oct 2018.
  14. ^ Dijkstra, K-D. B., G. Bechly, S. M. Bybee, R. A. Dow, H. J. Dumont, G. Fleck, R. W. Garrison, M. Hämäläinen, V. J. Kalkman, H. Karube, M. L. May, A. G. Orr, D. R. Paulson, A. C. Rehn, G. Theischinger, J. W. H. Trueman, J. van Tol, N. von Ellenrieder, & J. Ware. 2013. The classification and diversity of dragonflies and damselflies (Odonata). Zootaxa 3703(1): 36-45.
  15. ^ Bechly, G. (2002): Phylogenetic Systematics of Odonata. in Schorr, M. & Lindeboom, M., eds, (2003): Dragonfly Research 1.2003. Zerf – Tübingen. ISSN 1438-034X (CD-ROM)
  16. ^ Dragonfly – The largest complete insect wing ever found
  17. ^ Mitchell, F.L. and Lasswell, J. (2005): A dazzle of dragonflies Texas A&M University Press, 224 pages: page 47
  18. ^ a b c Bybee, Seth; Córdoba-Aguilar, Alex; Duryea, M. Catherine; Futahashi, Ryo; Hansson, Bengt; Lorenzo-Carballa, M. Olalla; Schilder, Ruud; Stoks, Robby; Suvorov, Anton (December 2016). "Odonata (dragonflies and damselflies) as a bridge between ecology and evolutionary genomics". Frontiers in Zoology. 13 (1): 46. doi:10.1186/s12983-016-0176-7. ISSN 1742-9994. PMC 5057408. PMID 27766110.
  19. ^ a b c Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed. Oxford University Press. pp. 355–358. ISBN 978-0-19-510033-4.CS1 maint: Multiple names: authors list (link)
  20. ^ Richard J. Bomphrey, Toshiyuki Nakata, Per Henningsson, Huai-Ti Lin (2016) Flight of the dragonflies and damselflies, Phil. Trans. R. Soc. B 371 20150389; DOI: 10.1098/rstb.2015.0389.
  21. ^ Norberg, R. Åke (1972). "The pterostigma of insect wings an inertial regulator of wing pitch". Journal of Comparative Physiology A. 81 (1): 9–22. doi:10.1007/BF00693547.
  22. ^ Golfieri, B., Hardersen, S., Maiolini, B., & Surian, N. (2016). Odonates as indicators of the ecological integrity of the river corridor: Development and application of the Odonate River Index (ORI) in northern Italy. Ecological Indicators, 61, 234-247.
  23. ^ Sahlén, Göran; Ekestubbe, Katarina (16 May 2000). "Identification of dragonflies (Odonata) as indicators of general species richness in boreal forest lakes". Biodiversity and Conservation. 10 (5): 673–690. doi:10.1023/A:1016681524097.

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