Small White-faced Darter
Leucorrhinia dubia (Vander Linden, 1825)
Order Dragonflies (Odonata)
Family Skimmer dragonflies (Libellulidae)
Conservation status: in Bulgaria: Critically endangered CR [B1a].
General distribution. The Scandinavian Peninsula, Denmark, Scotland, England, Belgium, the Netherlands, Luxemburg, Germany, Switzerland, Liechtenstein, Austria, the Czech Republic, Poland, Lithuania, Latvia, Estonia and to the east through Siberia to Japan. To the south of this major part of the range, it is found in few localities in the mountains of Spain, France, Italy, Romania and Bulgaria.
Distribution and abundance in Bulgaria. A high mountain species recorded in the Tiha Rila site near the Rilska River above Rila Monastery (2001) [1] and later also found in another four localities in the same area: near the lakes Smradlivoto and Manastirskite (unpublished data). The over 200 exuviae found within a day prove the local abundance of the species.
Habitats. Mountainous peatbogs with a predominance of mosses of the genera Sphagnum and Drepanocladus [1]. Their shores and shallow sections are overgrown with grass vegetation with the presence of thread rush (Juncus filiformis).
Biology. The nymphs of the species live in pelophilic cenosis [1]. They develop in the shallows between the stems of Juncus filiformis, where exuviae and emerging specimens have been found. Near the water body, the males perch on stones or on the soil. The eggs are laid on the free water surface in proximity to overgrowths with moss.
Similar species. Leucorrhinia pectoralis, from which it differs in the colouring of the body: in L. dubia the face is white and the body is dark, with red spots on the abdominal tergites.
Negative factors. Shallowing of the free water area of the basin and moss overgrowing with peat.
Conservation measures taken. All localities fall within the Rila Monastery Natural Park.
Conservation measures needed. Maintenance of the structure of the habitat. Inclusion of Leucorrhinia dubia as a priority species in the Management Plan of the Rila Monastery Natural Park. Monitoring of the vegetation overgrowth. Assessment of the size of the populations in the localities known so far. Studies on the diurnal activity of the adult, the behaviour in establishing territories, in mating and egg laying. Estimation of the natural and anthropogenic threats for the species.
References. 1. Marinov, Simov, 2004.
Author: Alexi Popov
