Balkan goldenring  (Cordulegaster heros)

The Balkan goldenring is classified as Near Threatened (NT) on the IUCN Red List (1).

One of Europe’s largest dragonflies (2), the Balkan goldenring (Cordulegaster heros) belongs to a group of dragonflies named for the yellow rings on their otherwise black bodies. Little information is available on the Balkan goldenring, but it resembles related Cordulegaster species in having a pattern of yellow bands and rings on the black thorax and abdomen (3).

Like other members of the Cordulegastridae family, the Balkan goldenring has large eyes which meet at a point on the top of the head. The front edge of each wing bears a long, thin, thickened black cell known as the ‘pterostigma’. The female Balkan goldenring has a long ovipositor at the end of the abdomen, and, as in closely related species, the female may be slightly larger than the male (3).

Two subspecies of the Balkan goldenring have been described: Cordulegaster heros heros and Cordulegaster heros pelionensis. These differ only in the shape or lack of a black band on the frons (the front, uppermost part of the head) (1).

The Balkan goldenring is endemic to parts of central and south-eastern Europe, from Austria and Slovakia to much of the Balkan region (1) (3). The exact limits of its distribution are not well known, but it may range as far east as the Ukraine (1). The subspecies C. h. pelionensis is reported to occur in northern Greece (3).

The fairly specific habitat requirements of the Balkan goldenring mean that its populations are quite scattered throughout its range (1).

This species generally inhabits shaded streams in mountains and hills. The Balkan goldenring usually prefers streams that have sandy or rocky beds (1), and its larvae only develop in clear, running water (3).

Little specific information is available on the biology of the Balkan goldenring. However, as in other Cordulegaster species, the adults are likely to be found near water, often quite low down in vegetation and with the abdomen hanging almost vertically (3). The adult Balkan goldenring feeds on small flying insects (3) and is a formidable predator, with huge eyes that give excellent vision (4).

After mating, the female Balkan goldenring lays eggs into the muddy bottom of a shallow stream. As in related species, this is likely to involve the female thrusting the ovipositor into the mud to lay the eggs while in flight (3). Unlike in some other dragonflies (4) (5), the male Balkan goldenring is unlikely to guard the female while the eggs are laid (3).

The larvae of Cordulegastridae species live buried in mud or gravel in the stream bed. Only the head, front legs and the tip of the abdomen are exposed, and from this hidden position the larva lies in wait for passing prey (3). Dragonfly larvae catch prey by shooting out the lower jaw, or ‘labium’, which is armed with hooks that impale the victim and drag it back to the mouth as the labium is retracted (4) (5).

As a dragonfly larva grows, it goes through a serious of developmental stages, or ‘instars’, before emerging from the water and moulting into the adult dragonfly. After it has emerged, the adult spends some time feeding and maturing before it breeds (4) (5). Cordulegaster species may spend as long as three or four years as a larva before developing into the adult form, but the adult may only live for a few weeks (3).

As with many European dragonflies, the main threat to the Balkan goldenring is the drying up of streams as a result of drought and the over-extraction of water for irrigation. Periods of drought are likely to become more severe with the effects of climate change (1) (6). Although it is locally common, this species has quite specialised habitat requirements and a rather patchy distribution, making it more vulnerable to local extinctions (1).

The Balkan goldenring’s habitat is also threatened by the destruction of forests through logging and fires, which can further contribute to the drying out of streams (1) (4).

There are not known to be any specific conservation measures currently in place for the Balkan goldenring. This species is listed on Annexes II and IV of the European Habitats Directive (1) (6) (7), but this is not respected in some countries, and water is still regularly extracted from the Balkan goldenring’s habitat (1).

Recommended conservation measures for this poorly known dragonfly include clarifying the extent of its distribution, particularly in countries such as Romania (1).

Find out more about the Balkan goldenring and its conservation:

• D’Aguilar, J., Dommanget, J.L. and Préchac, R. (1986) A Field Guide to the Dragonflies of Britain, Europe and North Africa. Collins, London.

More information on dragonfly and damselfly conservation:

• Moore, N.W. (1997) Dragonflies: Status Survey and Conservation Action Plan. IUCN/SSC Odonata Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at:
  http://data.iucn.org/dbtw-wpd/edocs/1997-042.pdf
• Kalkman, V.J., Boudot, J.P., Bernard, R., Conze, K.J., De Knijf, G., Dyatlova, E., Ferreira, S., Jović, M., Ott, J., Riservato, E. and Sahlén, G. (2010) European Red List of Dragonflies. IUCN and Publications Office of the European Union, Luxembourg. Available at:
  http://ec.europa.eu/environment/nature/conservation/species/redlist/downloads/European_dragonflies.pdf