Editing Aeshna isoceles

{{Short description|Species of dragonfly}}
{{Speciesbox
| name = Green-eyed hawker
| image = AeshnaIsocelesMale.jpg
| status = LC
| status_system = IUCN3.1
|status_ref=<ref name="iucn status 19 November 2021">{{cite iucn |author=Clausnitzer, V. |date=2018 |title=''Aeshna isoceles'' |volume=2018 |page=e.T158692A72305432 |doi=10.2305/IUCN.UK.2018-1.RLTS.T158692A72305432.en |access-date=19 November 2021}}</ref>
| taxon = Aeshna isoceles
| authority = ([[Otto Friedrich Müller|Muller]], 1767)
| range_map = Distribution of Aeshna isoceles.png
| range_map_caption = Range of ''Aeshna isoceles''
}}

'''''Aeshna isoceles''''' (or '''''isosceles''''') is a small hawker [[dragonfly]] that is found in Europe, mostly around the [[Mediterranean]], and the lowlands of North Africa. Its common name in English is '''green-eyed hawker'''. In the United Kingdom it is a localised species, and is called the '''Norfolk hawker'''. 

''Aeshna isoceles'' is brown, with green eyes, clear wings, and a yellow triangular mark on the second [[Abdomen#Invertebrates|abdominal]] segment which gave rise to its [[scientific name]]. It used to be in the genus ''[[Anaciaeschna]]'' as it different in several ways from the other members of the genus ''[[Aeshna]]'' to which it now belongs.

==Identification==
''A. isoceles'' is one of only two brown hawkers found in Europe, the other is ''[[Aeshna grandis|A. grandis]]''. Both have a brown thorax and abdomen but ''A. isoceles'' has green eyes and clear wings and a diagnostic yellow triangular mark on the second [[Abdomen#Invertebrates|abdominal]] segment. The hindwings have an amber patch at their base. In contrast ''A. grandis'' has yellowish wings and blueish eyes. The green eye of ''A. isoceles'' stands out even in flight and in practice it is not difficult to tell these two dragonflies apart. In addition to the morphological differences ''A. isoceles'' is on the wing much earlier in the year than ''A. grandis''.

==Distribution and habitat==
''A. isoceles'' is found in central [[Europe]] and around the [[Mediterranean]] and, the lowlands of [[North Africa]]. It is more common in eastern Europe than the south western Europe; it occurs in [[Spain]] and [[Portugal]] but is local.

It is found in wet areas, ponds, ditches and marshes, with dense vegetation and, in studies carried out in England, was found to be associated with [[Water-soldier]] (''Stratiotes aloides'').

===Status in Britain===
The Norfolk hawker has always been a scarce and local insect in Britain. It used to be found in the [[Cambridgeshire]] [[fen]]s but by the early 1980s the populations had greatly declined. It is now confined to relatively unpolluted fens and grazing marshes in the Broadlands of [[Norfolk]] and north-east [[Suffolk]].<ref>{{cite web|title=The Norfolk Hawker|url=http://british-dragonflies.org.uk/species/norfolk-hawker|publisher=[[British Dragonfly Society]]|access-date=15 October 2010}}</ref> It can be found in [[Hickling Broad]] and two [[national nature reserve (United Kingdom)|national nature reserve]]s: [[Mid-Yare NNR]] and [[Ludham - Potter Heigham NNR]] and at Castle Marshes in the [[Barnby Broad and Marshes]] SSSI. Since 2011 the species has also been recorded in the Stour valley in east Kent<ref>{{cite web |url=https://british-dragonflies.org.uk/content/rare-dragonfly-spreading-uk |title=Rare Dragonfly Spreading In the UK {{!}} british-dragonflies.org.uk |website=british-dragonflies.org.uk |url-status=dead |archive-url=https://web.archive.org/web/20171022141712/https://british-dragonflies.org.uk/content/rare-dragonfly-spreading-uk |archive-date=2017-10-22}}</ref> where egg laying has been observed and it appears to be spreading. It is protected under Schedule 5 of the [[Wildlife and Countryside Act 1981]]<ref>{{cite web|title=Wildlife and Countryside Act 1981 |url=http://www.opsi.gov.uk/RevisedStatutes/Acts/ukpga/1981/cukpga_19810069_en_27#v00187-sch8 |publisher=[[Government of the United Kingdom]] |access-date=15 October 2010 |url-status=dead |archive-url=https://web.archive.org/web/20090830002954/http://www.opsi.gov.uk/RevisedStatutes/Acts/ukpga/1981/cukpga_19810069_en_27 |archive-date=30 August 2009 }}</ref> and listed in Category 1 ([[Endangered species|endangered]]) in the British Red Data Books on Insects.<ref>{{cite web|title=The Odonata Red Data List for Great Britain|url=http://www.jncc.gov.uk/pdf/speciesstatus11_web.pdf|publisher=[[Joint Nature Conservation Committee]]|access-date=15 October 2010}}</ref>

==Behaviour==
{{multiple image | direction = horizontal | total_width= 350 | header = | footer = | image1 = Male Aeshna isoceles in flight.jpg | alt1 = aaa | caption1 =Male in flight| image2 = Norfolkhawker1.jpg | alt2 =bbb | caption2 = Female in the process of laying eggs }}

''Aeshna isoceles'' is one of the earliest ''[[Aeshna]]'' dragonflies to be on the wing with a flight period from May to August. Adults do not spend as much time on the wing as other ''Aeshnas''. Males will fly around over a stretch of water defending a territory and if the pond is small the male will hover over the centre of the pond. Unlike other aeshnas, where the adults seem to be continuously on the wing beating up and down their territory, male ''A. isoceles'' come to rest on vegetation from time to time. Females [[Oviposition|oviposit]] onto plants and the eggs hatch in about 2 weeks. Larval development takes 2 years.

==Systematics==
This species was first described as ''Libellula quadrifasciata, var. 36. isoceles'' by Muller in 1764. It has since been called ''Aeshna rufescens'' and ''Aeshna chysophthalmus'' and more recently ''Anaciaeschna isoceles''. It is by this last name that it is referred to in many books. It has since been included into the genus ''Aeshna'' and in many books is called ''Aeshna isoceles'': however the original specific name was ''isosceles''. Dijkstra and Lewington (2006) and Boudot JP., ''et al.'' (2009) both call it ''Aeshna isoceles'' whereas Askew, R.R. (2004), and earlier books, refer to it as ''Aeshna isosceles''.

A [[molecular phylogenetics|molecular phylogenetic]] analysis of the family Aeshnidae published in 2023 recovered ''Aeshna isoceles'' outside the genus ''Aeshna'', leading the authors of the paper to establish a new genus '''''Isoaeschna''''' for the species.<ref>{{cite journal|last1=Schneider|first1=T.|last2=Vierstraete|first2=A.|last3=Kosterin|first3=O. E.|last4=Ikemeyer|first4=D.|last5=Hu|first5=F.-S.|last6=Snegovaya|first6=N.|last7=Dumont|first7=H. J.|year=2023|title=Molecular Phylogeny of Holarctic Aeshnidae with a Focus on the West Palaearctic and Some Remarks on Its Genera Worldwide (Aeshnidae, Odonata)|journal=[[List of MDPI academic journals|Diversity]]|volume=15|issue=9|page=950|doi=10.3390/d15090950|doi-access=free|url=https://www.mdpi.com/1424-2818/15/9/950}}</ref>

==References==
{{Reflist}}

==Sources==
* Askew, R.R. (2004) ''The Dragonflies of Europe''. (revised ed.) Harley Books. {{ISBN|0-946589-75-5}}
* d'Aguilar, J., Dommanget, JL., and Prechac, R. (1986) ''A field guide to the Dragonflies of Britain, Europe and North Africa''. Collins. pp336. {{ISBN|0-00-219436-8}}
* Boudot JP., ''et al.'' (2009) ''Atlas of the Odonata of the Mediterranean and North Africa''. ''Libellula'' Supplement 9:1-256.
* Dijkstra, K-D.B & Lewington, R. (2006) ''Field Guide to the Dragonflies of Britain and Europe''. British Wildlife Publishing. {{ISBN|0-9531399-4-8}}.

==External links==
*{{cite web|title=Norfolk Hawker|url=http://www.norfolkdragons.co.uk/species/isosceles.shtml|work=The Dragonflies and Damselflies of Norfolk|access-date=15 October 2010|archive-url=https://web.archive.org/web/20110725161103/http://www.norfolkdragons.co.uk/species/isosceles.shtml|archive-date=2011-07-25|url-status=dead}}
* [https://www.odonata.org.uk/species/isoaeschna-isoceles/ Isoaeschna isoceles (Green-eyed Hawker/Norfolk Hawker)] from Odonata
* [https://www.inaturalist.org/taxa/1510501-Isoaeschna-isoceles Norfolk Hawker (Isoaeschna isoceles)] from [[iNaturalist]]

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{{Taxonbar|from=Q1435436|from2=Q55650594|from3=Q1808575|from4=Q47022039|from5=Q134087579|from6=Q134087593}}
[[Category:Aeshnidae]]
[[Category:Dragonflies of Europe]]
[[Category:Norfolk Broads]]
[[Category:Insects described in 1767]]
[[Category:Taxa named by Otto Friedrich Müller]]