Aeshna isoceles: Difference between revisions
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''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 [[Portrigal]] but is local. It occurs as far north as Norfolk in England where is is found in the [[The Broads]], an area with similar protection to a [[National park]]. In [[Norfolk]] it can be found in [[Hickling Broad]] and two [[National Nature Reserve]]s: [[Mid-Yare NNR]] and [[Ludham - Potter Heigham NNR]]. |
''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 [[Portrigal]] but is local. It occurs as far north as Norfolk in England where is is found in the [[The Broads]], an area with similar protection to a [[National park]]. In [[Norfolk]] it can be found in [[Hickling Broad]] and two [[National Nature Reserve]]s: [[Mid-Yare NNR]] and [[Ludham - Potter Heigham NNR]]. |
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It is found wet areas, ponds, ditches and marshes, with dense vegetation and |
It is found wet areas, ponds, ditches and marshes, with dense vegetation and associated with [[Water-soldier]] (Stratiotes aloides). |
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==Behaviour== |
==Behaviour== |
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It is one of the earliest ''[[Aeshna]]'' dragonflies to be on the wing with a flight period from May to August. |
It is one of the earliest ''[[Aeshna]]'' dragonflies to be on the wing with a flight period from May to August. |
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==Systermatics== |
==Systermatics== |
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This species was first discribed as ''Libellila quadrifasciata, var. 36. isoceles'' by Muller in 1767. It has since been called ''Aeshna rufescens'' and ''Aeshna chysophthalmus'' and more recently ''Anaciaeschna isosceles''. It is by this last name that it is refered to in many books. It has since been included into the genus ''[[Aeshna]]'' and in many books is called ''Aeshna isosceles'': however the original specific name was ''isoceles''. Dijkstra and Lewington (2006) call it ''Aeshna isoceles''. |
This species was first discribed as ''Libellila quadrifasciata, var. 36. isoceles'' by Muller in 1767. It has since been called ''Aeshna rufescens'' and ''Aeshna chysophthalmus'' and more recently ''Anaciaeschna isosceles''. It is by this last name that it is refered to in many books. It has since been included into the genus ''[[Aeshna]]'' and in many books is called ''Aeshna isosceles'': however the original specific name was ''isoceles''. Dijkstra and Lewington (2006) call it ''Aeshna isoceles''. |
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Revision as of 08:59, 3 April 2010
| Norfolk Hawker | |
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| Species: | A. isoceles
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| Binomial name | |
| Aeshna isoceles (Muller, 1767)
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Aeshna isoceles is a hawker dragonfly that is found in Europe, mostly around the Mediterranean the lowlands of North Africa. Its common name in English is the The Green-eyed Hawker. In the UK it is a rare and local species and is known as the Norfolk hawker. It has a brown colour with green eyes and clear wings and also yellow triangular mark on the second abdominal segment which gave rise to its scientific name. It used to be in the genus Anaciaeschna as it has several differences from the other members of the Aeshna genus. Its specific name is often spelt isosceles
Identification
A. isoceles is one of only two brown hawkers found in Europe, the other is 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 abdominal segment. The hindwings have a amber patch at their base. In contrast A. grandis has yellowish wings and blueish eyes.
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 Portrigal but is local. It occurs as far north as Norfolk in England where is is found in the The Broads, an area with similar protection to a National park. In Norfolk it can be found in Hickling Broad and two National Nature Reserves: Mid-Yare NNR and Ludham - Potter Heigham NNR.
It is found 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).
Behaviour
It 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. Females oviposit onto plants and the eggs hatch in about 2 weeks. Larval development takes 2 years.
Systermatics
This species was first discribed as Libellila quadrifasciata, var. 36. isoceles by Muller in 1767. It has since been called Aeshna rufescens and Aeshna chysophthalmus and more recently Anaciaeschna isosceles. It is by this last name that it is refered to in many books. It has since been included into the genus Aeshna and in many books is called Aeshna isosceles: however the original specific name was isoceles. Dijkstra and Lewington (2006) and Boudot JP., et al. (2009) both call it Aeshna isoceles wheras Askew, R.R. (2004),and earlier books, refer to it as Aeshna isosceles.
References
- Askew, R.R. (2004) The Dragonflies of Europe. (revised ed.) Harley Books. ISBN 0946589755
- d'Aguilar, J., Dommanget, JL., and Prechac, R. (1986) A field guide to the Dragonflies of Britain, Europe and North Africa. Collins. pp336. ISBN 0002194368
- 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 0953139948.
In Britain, the Norfolk Hawker is protected under Schedule 5 of the Wildlife and Countryside Act 1981, and listed in Category 1 (endangered) in the British Red Data Books on Insects.
External links
