Orthetrum chrysostigma
Orthetrum chrysostigma (Burmeister, 1839)
Local names: Epaulet skimmer, Rahmstreif-Blaupfeil, Epauletoeverlibel
Species Information
Description
One of Africas most common dragonflies, extending to some southern parts of Europe. It is brown yellow in colour with light-blue pruinosity in the mature males. It is similar in size and appearance to O. coerulecens for the abundant light-blue pruinosity covering the bodies of the males and the yellowish pterostigma. It can be distinguished from the other skimmers thanks to the abdomen that is rather slender and further narrows down at S3 and S4. The thorax of both males and females has a single distinctive whitish band bordered with black that becomes less visible in older males. The sides of the thorax and abdomen in females tend to take on a pink colouration.
Diagnostic features are:
- Abdomen rather slender and waisted near base (S3-S4).
- Thorax with a conspicuous whitish stripe beneath each forewing base, accentuated by black outline (obscured in males).
- Membranules are sooty and usually bordered by a yellow patch. On other species the base of the wing is generally clear. The larger, broader-bodied O. brunneum and O. nitiderve lack stripes on the thorax, and have whitish membranules. In the smaller O. coerulescens, the stripes lie more anteriorly and are less white. In the even smaller O. taeniolatum there are three stripes on each side, and these are accentuated by black only on one side. Both smaller species are un-waisted and have grey-brown membranules.
Size
Habitat
In Europe, Orthetrum chrysostigma favours warm, open and sunlit running and standing waters in arid to semi-arid lowlands. Habitats range from small streams which dry out in summer to large permanent rivers, and from natural ponds and lakes to large man-made reservoirs. Preferred habitats have little aquatic vegetation with rocky, stony or sandy banks that heat up quickly. These habitat requirements restrict the species to standing waters where considerable changes in water level limit the establishment of extensive aquatic or bank side vegetation. In Africa, however, O. chrysostigma also reproduces in overgrown habitats. In Namibia, it exhibits rapid larval development of less than 50 days, allowing it to occur in temporary waters and to produce several generation a year in perennial waters.
Distribution
Orthetrum chrysostigma is found throughout Africa and Madagascar and is common in the northern Maghreb. It reaches the Canary Islands, Iberian Peninsula, Cyprus and the east Aegean Islands. In south-east Asia it is restricted to Turkey, the Levant, parts of the Arabian Peninsula and the southern half of Iran. The European range includes the Iberian Peninsula, the Maltese Islands, a small number of east Mediterranean islands and the Canary archipelago. The species is widely distributed and common at low elevations in the south-west and the east of the Iberian Peninsula. It is the most common Skimmer in southern Portugal. It is comparatively rare in the eastern Mediterranean islands where it is known from about 30 river systems and standing water bodies from Rhodes, Kos, Lesbos and Cyprus.
Flight Period
April to August
Behavior
In Turkey it is said to perch rarely on the ground or on rocks, and never in the obelisk position (in contrast to O. taeniolatum)
Conservation Status
Similar Species
Orthetrum coerulecens, Orthetrum nitiderve, Orthetrum brunneum, Orthetrum taeniolatum
External Links
Genus: Orthetrum
Orthetrum is a large genus of dragonflies in the Libellulidae family. They are commonly referred to as skimmers.
Identification
Almost every blue to grey pruinose dragonfly with clear wings will be an Orthetrum male. The combination of a clear base, at most yellow-tinted, and 10-14 forewing cross-veins (thus last antenodal one is complete) is unique for a libellulid.
separation from other genera
Libellula species are similar in venation, stature and pruinosity, but have large dark patches at the hindwing base. Pruinose Leucorrhinia species are dark, with a contrasting white face and also dark hindwing patches. The rather plainly brown females and young males of most Orthetrum species are often mistaken for Sympetrum and Crocothemis. The species in both these genera normally have the last antenodal cross-vein incomplete; Sympetrum has only 6-7 complete forewing antenodal cross-veins, and Crocothemis has large yellow patches at the hindwing base. Especially fresh yellow O. cancellatum and the club-tailed black-and-pale O. sabina superficially resemble gomphids, but their eyes touch each other.
Separation of the species
Some 60 Orthetrum occur in Australia, Eurasia and particularly Africa. The species are often difficult to identify. This is especially true for males, whose markings have become obscured by pruinosity, thus appearing very unlike females and younger males. For convenience, the species can be divided into three groups. In most of Europe, separating O. albistylum from O. cancellatum (group 1) and O. brunneum from O. coerulescens (group 3) will cause the greatest difficulty. In the Mediterranean, two diagnostic species in group 2 and three additional species in group 3 occur. Because up to four species of species group 3 may occur together in Iberia, north Africa or Turkey, identification might be difficult. Examination of the male's secondary genitalia with a hand lens will be most decisive.
| Group | Species |
|---|---|
| Group 1 | O. albistylum O. cancellatum |
| Group 2 | O. trinacria O. sabina |
| Group 3 | O. brunneum O. chrysostigma O. coerulescens O. nitiderve O. taeniolatum |
Behaviour
Active species, often perching on the ground or stones. Male guards the female during oviposition, usually by hovering above her and chasing off rival males.
Family: Libellulidae
The skimmers or perchers and their relatives form the Libellulidae, the largest dragonfly family in the world. It is sometimes considered to contain the Corduliidae as the subfamily Corduliinae and the Macromiidae as the subfamily Macromiinae. Even if these are excluded, there still remains a family of over 1000 species. With nearly worldwide distribution, these are almost certainly the most often seen of all dragonflies.
The genus Libellula is mostly New World, but also has one of the few endangered odonates from Japan: Libellula angelina. Many of the members of this genus are brightly colored or have banded wings. The related genus Plathemis includes the whitetails. The genus Celithemis contains several brightly marked species in the southern United States. Members of the genus Sympetrum are called darters (or meadowhawks in North America) and are found throughout most of the world, except Australia. Several Southern Hemisphere species in the genera Trithemis and Zenithoptera are especially beautiful. Other common genera include Tramea and Pantala.
The libellulids have stout-bodied larvae with the lower lip or labium developed into a mask over the lower part of the face.
The family name may have been derived from the Latin libella which means booklet.