''Chalcolestes parvidens'', formerly ''Lestes parvidens'', is a damselfly of the family Lestidae. It has a metallic green body and at rest it holds its wings away from its body. Its common name in English is the eastern willow spreadwing.

Taxonomy

The genus ''

Chalcolestes ''Chalcolestes'' is a small genus of damselfly in the family Lestidae. They are commonly known as Willow Spreadwings. They are similar to the Spreadwings of the genus Lestes ''Lestes'' is a genus of damselfly in the family Lestidae. The fami ...

'' is separated from ''Lestes'' because of differences in their larvae. ''C. parvidens'' is closely related to '' C. viridis'' and used to be considered a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of ''C. viridis'', however there are small morphological differences between the two species both as adults and larvae and analysis of proteins from the two species, by

electrophoresis Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric fie ...

, also supports their separation into two species, but they are hard to tell apart in the field.

Distribution and habitat

''Chalcolestes parvidens'' is found in eastern and central Europe, in Croatia, Bulgaria, Greece, Italy, Syria, Jordan, Israel and Turkey. It is found on islands in the eastern Mediterranean; on Cyprus, Corsica, Crete and Sicily. In Italy and the Balkans both ''C. parvidens'' and ''C. viridis'' occur together. It is only in the last 20 years that odonaterists have been separating ''C. parvidens'' from ''C. viridis'' so some of the older records for ''C. viridis'' will probably be for ''C. parvidens''.

Identification

In the field it is not possible to reliably distinguish ''C. viridis'' from ''C. parvidens''. Both species are mainly metallic green, like the ''Lestes'' damselflies, but larger and darker but they do not have a powder blue pruinescence which is common in Lestes. The

pterostigma The pterostigma (plural: pterostigmata) is a group of specialized cells in the outer insect wing, wings of insects, which are often thickened or coloured, and thus stand out from other cells. It is particularly noticeable in dragonfly, dragonfli ...

is pale brown and outlined in black. The

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

has thin yellow antehumerals and broader yellow stripe above a thin black line on each side; the upper edge of the stripe is irregular. Both ''C. viridis'' and ''C. parvidens'' have a prominent spur-like marking on the side of the thorax.

Behaviour

Flight period is generally from May to November. In Cyprus, the flight season is from early April to January. Behaviour is similar to that described in ''C. viridis''. It hangs with wings spread wide, often in the shade of trees near breeding water. Mature males defend vertical territories in marginal shrubs and small trees where they find and mate with females in the normal damselfly manner forming the wheel position. Egg laying occurs with the pair in tandem, the eggs being laid into incisions in the bark of overhanging branches, not into submerged vegetation as is the case in many damselflies. Egg laying can result in distinct oval galls forming in the shrub's bark. The eggs develop rapidly for a few weeks and then enter a diapause state. In this state the eggs development is very slow and it is in this state that the eggs overwinter. The following spring the eggs hatch, the larvae drop into the water and start to develop. Growth is rapid and adults can emerge in a couple of months. After emerging the adults move away from water to mature. In this stage of their life-cycle which in ''C. parvidens'' is quite long, the immature adults cannot breed. The adults need a period of time for their reproductive organs to develop and this non-breeding period also stops the adults breeding too early in the season. If the females lay eggs early in the year the eggs will develop when it is to warm to for them to enter diapause. They might hatch out before winter and the resultant larva will die when winter temperatures occur. When fully mature the adults return to water and start breeding.

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