Species - Enallagma ebrium

Taxonomic Hierarchy for Freshwater Invertebrate Collection


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Enallagma ebrium

Freshwater Invertebrate Collection

Common Namemarsh bluet SeasonalityAdults fly from June to August in Alberta. Flight season extends in more temperate regions. IdentificationA smaller bluet, with adults ranging from 28-34 mm in total length and 16-21 mm in hindwing length. Males are predominantly blue (andromorphic), while females are polymorphic and range from light blue to yellow-green, the former being more common. Thoracic stripes are typical of most bluets in both sexes. Black abdominal banding is present in both sexes. In males, the first three black bands occurring on abdominal segments 3 to 5 increase in width towards the end of the abdomen. Male abdominal segments 6, 7 and 10 are mostly black on the dorsal surface, segments 8 to 9 are predominantly blue. Males have a large apical spot on the dorsal surface of abdominal segment 2. In females, the abdomen is mostly black due to broadening of abdominal bands on the dorsal surface. Male eyes are dorsally black and ventrally blue, while female eyes are dorsally brown and ventrally tan to pale green. Postocular spots are prominent and rarely separated, forming a dumbbell shape in both sexes. In certain populations, abdominal banding may be wider in marsh bluets than in Hagen’s bluets (Enallagma hageni); however, over much of its range, marsh bluets are virtually indistinguishable from Hagen’s bluets except when viewed under magnification. Male marsh bluets and Hagen’s bluets differ in morphology of cerci. The large size of the mesostigmal plates, or “shoulder pads”, of female marsh bluets differentiate them from all other female bluets save Hagen’s bluets; however, the mesostigmal plates of female marsh bluets lie flat towards their posterior end, while the mesostigmal plates of female Hagen’s bluets are raised above the thorax. Compared to marsh bluets, northern bluets (Enallagma annexum), boreal bluets (Enallagma boreale), and familiar bluets (Enallagma civile) may be similar in colouration, but all 3 are notably larger (Acorn 2004; Paulsen 2009).

Taxonomic Hierarchy for Freshwater Invertebrate Collection