Orthetrum brunneum
Orthetrum brunneum Fonscolombe, 1837
Local names: Southern skimmer, Südlicher Blaupfeil, Zuidelijke oeverlibel, Orthétrum brun, Blåpannad sjötrollslända
Species Information
Description
A rather plain, medium sized skimmer that is common on running waters in the south. Being somewhat featureless it is most easily separated from similar species by exclusion. The light coloured pterostigma distinguishes it from Orthetrum albistylum and O. cancellatum. It could be confused with O. coerulescens from which it differs by the abdomen being slightly wider, the pterostigma being smaller and light brown instead of yellow, and in the males the frons being pale blue rather than yellow brown. In the mature males, covered in light blue pruinosity, the thorax and the abdomen has the same colour, which overall is lighter than in O. coerulescens and the yellow base colour shows through. On the wings, above the radial vein, there is a row of double cells, whereas in O. coerulescens the row consists of single cells. Compared to O. nitderve, the pterostigma is shorter and the venation is entirely black.
When not pruinose the abdomen is uniformly yellow-brown with a thin longitudinal black line down the centre upper side of the abdomen. Near the end of each segment, a pair of spots flank this line. These are usually fused to a cross-bar in O. coerulescens but seldom so in O. brunneum.
Size
Habitat
Orthetrum brunneum is found at a wide range of habitats including sunny streams, slow-flowing rivers, ditches, seepages and springs as well as man-made pools, quarries and gravel pits. The species is mostly found at sites in early stages of succession with relatively little bank side or aquatic vegetation. In the north of its range it is often a pioneer species and appear promptly at man-made, warm habitats, declining and even disappearing as the vegetation develops. It is a lowland species in most of Europe and in the Alps populations above 600 m is rare; however it is more common in mountains in the south of its range.
Distribution
Otrhetrum brunneum is widespread and common in the southern part of Europe, becoming scarcer to the north. In large parts of central and north-western Europe it is widely distributed although generally uncommon, and has few permanent populations. The scarcity of records in Ukraine and Russia and, especially its absence from the well-explored southern Urals suggests that the species is genuinely rare and restricted to southern latitudes in this part of Europe.
Flight Period
May to September
Behavior
This species is less active than O. coerulescens and has a rather different behaviour. It tends to alight on the bare ground or rocks not far from the streams, or at most on the low grass like O. nitderve and unlike O. coerulescens that always perches on small bushes or on top of small grassy vegetation.
Conservation Status
Similar Species
Orthetrum coerulescens, Orthetrum albistylum, Orthetrum cancellatum
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.