23 August 2012

Black Pennant Selysiothemis nigra – Dhahran Hills

A good number of Black Pennant Selysiothemis nigra are currently around the edges of the percolation pond in Dhahran Hills. They are mainly using the grasses as perches but are not see away from the scrub surrounding the pond so presumably they like the water available at this site which is not surprising as they favour standing water, brackish lagoons, salt marshes and ponds especially in desert regions with adults hovering frequently, a meter or so above the ground. They are common in the Middle East and seen regularly in the Eastern Province of Saudi Arabia, where many are thought to be migratory. The female releases eggs as she strikes the water surface with the tip of her abdomen.

The Black Pennant is a small and graceful dragonfly, distinguished by its large, fragile-looking wings and distinctive ‘equals sign’ shaped pterostigma (the dark coloured cells near the tip of the wings). The alternative name ‘the Desert Darter’ comes from the way in which it makes short flights, from perch to perch when it hunts or flies. The male is uniformly black in colour (often blue black), although occasionally develops a whitish patch on the thorax and abdomen, giving it a frosty or dusty appearance. Females and immature males have a more sandy-brown colouration, with extensive black markings. The wings are clear and shiny, with very fine veins patterning the surface. It has a scattered distribution in northern Africa, Central Asia, the Middle East and in several European Mediterranean countries. It uses wetland habitats such as temporary pools of water, shallow standing coastal waters, reservoirs, canals and irrigation ditches during the aquatic stages of its life cycle, while terrestrial habitats of the adult include desert and grassland. An energetic dragonfly, the black pennant is an opportunistic predator which will catch a wide variety of small insect prey. Like other dragonflies of the Libellulidae family, the black pennant may adopt a distinctive ‘obelisk posture’ when temperatures soar during the day, pointing the abdomen directly at the sun in order to prevent the body from overheating.