About Orthetrum coerulescens (Fabricius, 1798)
Orthetrum coerulescens (Fabricius, 1798), commonly called the keeled skimmer, is a species of dragonfly that reaches a body length of 40–44 millimetres (1.6–1.7 in). These dragonflies have a thorax marked with pale yellow ante-humeral stripes. In males, the color of these stripes fades as the dragonfly ages. The abdomen is rather slim and has a clearly visible dorsal keel. Males have blue-grey eyes and blue pruinescence on the abdomen that becomes more developed as they age. Young males are yellow-brown. In contrast, some androchrome females develop the male’s bluish coloration at the end of their reproductive cycle. Females have a yellowish-brown abdomen, with a thin median black line and small transverse lines at the connections between the various abdominal segments. The hyaline wings have a yellow costa and a long yellow-brown pterostigma that measures about 4 mm. When at rest, these dragonflies usually hold their wings well forward. This species resembles the black-tailed skimmer, but it is smaller and slimmer, and males have no black tip on the abdomen. Females and immature males lack the black abdominal pattern seen on black-tailed skimmers. The keeled skimmer is common in central and southern Europe, marginally extending into Russia, and is also found across North Africa. It is locally common in western Britain and Ireland. Confirmed countries where this species is present include Afghanistan, Albania, Algeria, Armenia, Austria, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Finland, France, Georgia, Greece, Hungary, Islamic Republic of Iran, Iraq, Ireland, Italy, Lebanon, Liechtenstein, Lithuania, Luxembourg, the former Yugoslav Republic of Macedonia, Montenegro, Morocco, Netherlands, Norway, Poland, Portugal, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Syrian Arab Republic, Tunisia, Turkey, Ukraine, and the United Kingdom. The typical favoured habitats of Orthetrum coerulescens are pools and streams located in acidic heath land, including wet heathland sites. It can sometimes be found alongside golden-ringed dragonflies in these areas.
