Orthetrum brunneum (Southern Skimmer / Güneyli Yusufcuk)

Orthetrum brunneum (Southern Skimmer / Güneyli Yusufcuk)

Orthetrum brunneum (Southern Skimmer / Güneyli Yusufcuk) [Male/Erkek] from Bornova, İzmir - 22.06.2009.

A rather plain, medium-sized skimmer that is common on running waters in the south. Males become totally blue, females are brown overall. Being somewhat featureless, it is most easily separated from similar species around the Mediterranean by exclusion.

Total length: 41-49mm, Abdomen length: 25-32mm, with a hind wing spans of 33-37mm. Size and shape between O. cancellatum (Black-tailed Skimmer) and O. coerulescens (Keeled Skimmer). Distinguished from former (and O. albistylum, White-tailed Skimmer) by its reddish-brown pterostigma and almost unmarked body that becomes largely blue in mature males. Most likely to be confused with O. coerulescens in most of its range, but visual distinguishing features are:

(1) somewhat larger and heavier, with a broader abdomen; (2) adult male has a whitish face with a blue hue, rather than a dirty pale brown; (3) thorax is plain brown, becoming entirely blue pruinose in mature male (in O. coerulescens the thorax seldom becomes densely pruinose and two paler antehumeral stripes- pale stripes on the thorax in front of the humeral suture- are often visible); (4) when not pruinose, the abdomen is uniformly brown, with a thin lengthwise black line down the centre. 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; (5) when mature, the pterostigma –conspicuously thickened and often darkened area on leading edge of wing tips, present in most odonates- is reddish brown, rather than yellow as in. O. coerulescens. These characters should be used as an indication of the identity of individuals (especially 4 and 5 are not fully reliable). Additional distinguishing features are: (6) pterostigma is relatively short (2.5-3mm); (7) the male's hamule –grasping organ of secondary genitalia- has a very large hook. Unlike in other Orthetrum species, it juts out well beyond the anterior lamina.

Southern Skimmers often perch on the ground or on stakes besides running water. They common around the Mediterranean; range extends to Mongolia. It has expanded northwards since the 1990s. Its habitat is mostly small streams, running ditches and seepages, preferring scantily vegetated sites more than O. coerulescens. Favours bare runnels in the north, e.g. in chalk or marl quarries. It flights from April to September.

References: 1. Chinery, M. (1986). Collins Guide to the Insects of Britain and Western Europe, Collins, Glasgow, 320 pp. 2. Dijkstra K.-D. (2006). Field Guide to the Dragonflies of Britain and Europe including Western Turkey and noth-Western Africa. British Wildlife Publishing, Dorset, UK. 320 pp. 3. Beaton, G. (2007). Dragonflies and Damselflies of Georgia and the Soustheast. University of Georgia Press, Athens, Georgia, 355 pp.