The following odonate exuvia is from a damselfly in Suborder Zygoptera.
The overall shape of the prementum (highlighted by a red rectangle) indicates this specimen is from Family Calopterygidae (Broad-winged Damselflies). Notice the embedded raindrop shape (highlighted by a purple rectangle), located toward the upper-center of the prementum — a key field mark for this family.
Two genera from Family Calopterygidae are common in the Commonwealth of Virginia: Hetaerina; and Calopteryx. For species in Genus Calopteryx the raindrop shape (Fig. 19) looks more like a diamond shape (Fig. 18), so it’s probably safe to infer this specimen is a species in Genus Hetaerina.
Related Resources
- Which family is it? – a blog post by Walter Sanford
- Identification Manual for the Damselfly Nymphs (Zygoptera) of Florida, by Johnny S. Richardson
Post Update: Congratulations to Doug Mills, Wally Jones, and Bob Perkins for correctly identifying the family of this exuvia.
Doug and Wally looked at the shape of the prementum. Bob looked at the antennae.
The long middle segment on the antennae is the key, found only on Calopterygidae nymphs. Nymphs of the other families have antenna segments that are progressively shorter from base to tip. Source Credit: Bob Perkins.
Looking at the prementum should enable you to identify all three families; looking at antennae works for only one family.
Copyright © 2022 Walter Sanford. All rights reserved.
Tags: Broad-winged Damselflies, exuvia, Family Calopterygidae, Genus Calopteryx, Genus Hetaerina, What is it?
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