Species - Enallagma hageni

Taxonomic Hierarchy for Freshwater Invertebrate Collection


1 result for "Enallagma hageni"

Enallagma hageni

Freshwater Invertebrate Collection

Common NameHagen's bluet SeasonalityAdults fly from June to August in Alberta. Flight season extends in more temperate regions. IdentificationA smaller bluet, with adults ranging from 27-33 mm in total length and 15-21 mm in hindwing length. Males are predominantly blue (andromorphic), while females are polymorphic and may be range from light blue to yellow-green to light brown. Thoracic stripes are typical of most bluets in both sexes. Black abdominal banding is present in both sexes. In males, the black bands occurring on abdominal segments 3 to 5 increase in width towards the end of the abdomen on the dorsal surface. Male abdominal segments 6, 7 and 10 are mostly black on the dorsal surface, and segments 8 and 9 are predominantly blue. Males have a prominent apical spot on the dorsal surface of abdominal segment 2. In females, the abdomen is predominantly black due to widening of abdominal bands on the dorsal surface. Male eyes are dorsally black and ventrally blue, while female eyes are dorsally brown and ventrally tan or or pale green. Postocular spots are prominent in both sexes, forming a dumbbell shape. Over much of its range, Hagen’s bluets are virtually indistinguishable from marsh bluets (Enallagma ebrium) except when viewed under magnification; however, in certain populations, abdominal banding may be narrower in Hagen’s bluets than in marsh bluets. Male Hagen’s bluets and marsh 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 except Hagen’s bluets; however, the mesostigmal plates of female Hagen’s bluets are raised above the thorax, while the mesostigmal plates of female marsh bluets lie flat towards their posterior end. Female Hagen’s bluets may also resemble female taiga bluets (Coenagrion resolutum), but may be differentiated by the presence of a spine on the ventral side of abdominal segment 8 in Hagen’s bluets. Northern bluets (Enallagma annexum), boreal bluets (Enallagma boreale), and familiar bluets (Enallagma civile) may be similar in colouration in both sexes, but all 3 are notably larger (Acorn 2004; Paulsen 2009).

Taxonomic Hierarchy for Freshwater Invertebrate Collection