Bulgarian emerald  (Somatochlora borisi)

The Bulgarian emerald is classified as Vulnerable (VU) on the IUCN Red List (1).

With its large emerald green eyes, the recently discovered Bugarian emerald (Somatochlora borisi) dragonfly (3), is typical of the Corduliidae family, commonly known as the emerald dragonflies (4) (5). The thorax of this species is metallic green, while the abdomen is dark green with a metallic sheen. At the base of the abdomen are wide yellow spots, which are very large on the under side of the first four or five abdominal segments in the female (4).

Published localities originate from nine streams in the Eastern Rhodopes and Istranca Mountains along the borders between Bulgaria, Greece and European Turkey (1) (4). Additional unpublished running water systems for this species have been recently discovered in south-east Bulgaria (6).

The Bulgarian emerald is found in and around forest rivers, in sections with low current (1).

Odonata species start their life as aquatic larvae, passing through a series of developmental stages or ‘stadia’ and undergoing several moults as they grow. Before the final moult (emergence), metamorphosis occurs in which the larvae transform into the adult form. Adults complete their metamorphosis after emergence and undergo a pre-reproductive phase known as the maturation period, when individuals normally develop their full adult colour (5) (7). Nothing has been recorded of the Bulgarian emerald’s social, reproductive or feeding behaviour, but certain details can be inferred from what is known about Somatochlora meridionalis, which occurs in the same habitat in the same area, and its western counterpart, S. metallica. Eggs would hatch four to ten weeks after deposition. The larval period would extend over two or three years and would involve 12 or 13 stadia. Larvae would live at the surface of the sediment and within leaf litter detritus accumulated at the bottom of the river. The so-called territorial behaviour of many Somatochlora species remains controversial and poorly depicted. After copulation, which occurs at variable distances from the banks and generally in tree crowns, Bulgarian emerald females return to the river to lay their eggs in calm, shaded areas, unaccompanied by the male (6).

Odonata feed on flying insects and are often generalised, opportunistic feeders, sometimes congregating around abundant prey sources such as swarms of other insects (7).

There are considered to be no immediate threats to this species as long as traditional human activities are maintained, such as extensive rearing of goats and sheep, which although produce a number of dispersed forest clearings and have little negative impact on this dragonfly. However, the intensive agriculture and conifer plantations that could result from inclusion in the European Union may pose significant future threats. Water pollution and stream-drying due to summer drought and climate change pose additional potential threats to the survival of this species (1).

Two of the rivers inhabited by this species are included in the Greek national Dadia Protected Area buffer zone, created in 1980, which is partly managed by the WWF-Greece and the Greek Ministry of Environment (1).