The dragonflies of the genus Sympetrum, known in North America as meadowhawks and in Europe as darters, are small and often very common. Worldwide there are currently sixty-one recognized species with the greatest species richness in eastern Asia and Japan, in North America there are fourteen species.
Recent phylogenetic research suggests that the genus radiated from a common ancestor in Asia, around 25 million years ago. (Two clades cloud the matter of origin. The Sympetrum illotum group, which includes related species in South America, and the Sympetrum fonscolombii group, which includes the two closely related migrants Sympetrum corruptum in North America and Sympetrum fonscolombii in Europe and Asia, could indicate a possible origin in South America).
These dragonflies are specialists of temporary wetlands with the unique trait of having exophytic eggs that overwinter in diapause. The hatching of the overwintering eggs is delayed until spring (again the exception being the two migrants S. fonscolombii and S. corruptum).
Because these dragonflies have evolved to make use of habitats that are fragmented and non-permanent, varying from year to year, populations of single species and assemblages of several species fluctuate greatly. Most are very good at dispersing from existing sites and colonizing new sites, with pinpoint accuracy in habitat selection.
Species, in Minnesota, are generally separated without difficulty. The exception being the three closely related species Sympetrum obtrusum, S. rubicundulum, and S. internum. But even among these three identification to species is not impossible and can often be determined in the field and in photographs.
The Sympetrum are not as difficult to identify as some people and some guidebooks might lead you to believe.
S. madidum (male) – Roseau County, MN – July 13, 2012
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