A dark colour form of Cordulegaster heros (Odonata: Cordulegastridae)

In July 2010 a dark colour form of the male of Cordulegaster heros was recorded at the Kamenný potok stream in the village of Modra-Piesok in the southern part of the Malé Karpaty Mts. in Slovakia. Differences between the typical colouring and the dark colour form are described.