Dark pincertail (Onychogomphus assimilis)
Classified as Vulnerable (VU) on the IUCN Red List 2006 (1).
This colourful dragonfly belongs to the Gomphidae family, commonly known as ‘clubtail dragonflies’ for the enlarged area at the tip of their abdomen (2). This species displays a rainbow of bright and beautiful colours, from the vivid turquoise blue eyes through to the pale-green body, which becomes increasingly yellow along the abdomen, and eventually ends in a conspicuous orange tip. The pale-green colour of the thorax is set off against contrasting black lines, and the brightly coloured abdomen is also interrupted by black rings of variable size, giving a striking striped appearance. The dark pincertail is a large clubtail, with the abdomen exceeding 40 mm in length (3).
The dark pincertail ranges from southwest Turkey to western Turkmenistan, including Armenia, Georgia and Iran (1) (4) (5).
Found in streams and rivers, preferring wooded environments (5).
Almost nothing is known of the dark pincertail’s reproductive biology, life history patterns or feeding behaviour. Nevertheless, there are general biological characteristics of dragonflies and damselflies (Odonata) that are likely to apply here. Odonata species start their life as aquatic larvae, passing through a series of developmental stages or ‘stadia’, undergoing several moults as they grow. This larval period can last anything between three months and ten years, depending upon the species (6), but is generally 2 to 4 years in West Palearctic clubtails (3). Before the final moult (emergence), metamorphosis begins, during which the larvae transforms into the adult form (6). From a physiological point of view, metamorphosis will end some days after emergence (3). After emergence, adults undergo a pre-reproductive phase known as the maturation period, and this is when individuals normally develop their full adult colour (6). The flight period of the dark pincertail, during which time it must mate, seems to extend from the end of April to the end of July (3). There is often fierce competition between males for access to reproductive females, and females typically begin to lay eggs in water immediately after copulation, often guarded by their mate. However, females of some species can store live sperm in their body for a number of days (6).
Odonata usually feed on flying insects, but are generalised, opportunistic feeders, and will often congregate around abundant prey sources such as swarms of other small insects, and sometimes also near beehives (6).
Despite its wide distribution, the dark pincertail is becoming increasingly vulnerable to extinction, with previously flourishing populations gradually diminishing or being destroyed completely. The main threats include water pollution, gravel pitting directly in streams, drying-up of streams due to water harnessing and irrigation, and expanding urbanisation (1). Additionally, the tourist industry is rapidly growing along the Turkish south coast, and the area is becoming increasingly populated and developed, leading to many localised extinctions (1).
There are currently no conservation measures targeting this species.
Authenticated (07/08/2006) by Jean-Pierre Boudot, CNRS, Université Henri Poincaré Nancy I, France.
- Metamorphosis: an abrupt physiological and physical change from the larval to the adult form.
- Palearctic: Of or relating to the geographic region that includes Europe, the northwest coast of Africa, and Asia north of the Himalaya Mountains, especially with respect to distribution of animals.
IUCN Red List (December, 2009)