Coenagrion mercuriale (Charpentier, 1840)
Mercury Bluet

Type locality: Europe, no locality data available.


Small, deep-blue damselfly, typical of small streams in the western Mediterranean. Male’s S2 is marked with a black double-horned triangle, which has been likened to Mercury’s helmet. Details of markings and appendages further identify it. Stouter than C. puella and among the smallest members of the genus. Male S2 marking is variable, not unlike that of other Coenagrion species, but typically resembles a head bearing a horned helmet. S3-6 seldom more than half black, S7 always with some blue at the base. Males are perhaps most easily identified by the exclusion of congeners likely in habitat: C. puella bears long lateral black spikes on the black end-rings of S3-6; C. caerulescens and C. scitulum have elongated pterostigmas and largely black S6-7. Females are dark and nondescript, again best recognised by the exclusion of other species. Male upper appendages are strongly hooked at the tip, like C. scitulum and C. caerulescens, but these are about as long as the lowers and also with distinct teeth at their base. Hind margin of female pronotum with tiny lobe in the middle, much smaller than that of C. scitulum. Some females are coloured more like males, with the pale areas on the abdomen larger and bluer. [Adapted from Dijkstra & Lewington 2006]

Habitat description

Mostly streams, but also headwaters, in open landscapes. Usually with emergent and often aquatic vegetation. From 0 to 2100 m above sea level.


confirmed: Algeria; Morocco; Tunisia

Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.


  • Charpentier, T. de (1840). Libellulinae Europaeae Descriptae et Depictae. Leopold Voss, Lipsiae, 1-180.

Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. [2020-11-26].