Beware of look-alikes!

Some species of dragonfly larvae/exuviae look similar to other species. Here are a couple of look-alikes from two different families that might fool you.

One species of Corduliidae in our region [North America], Epitheca princeps, resembles the macromiid general body shape and is nearly as large, but the legs are short compared to its body dimensions and it lacks a triangular frontal projection. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 329.

The first annotated image shows a ventral view of a Prince Baskettail (Epitheca princeps) exuvia. E. princeps is a member of Family Corduliidae (Emeralds).

Prince Baskettail (Epitheca princeps) | exuvia (ventral)

Notice the appearance of the E. princeps exuvia is quite similar to the Stream Cruiser (Didymops transversa) exuvia shown below. D. transversa is a member of Family Macromiidae (Cruisers).

Stream Cruiser (Didymops transversa) | exuvia (ventral)

The E. princeps exuvia features lateral spines and well-developed mid-dorsal hooks on some abdominal segments. Notably “it lacks a triangular frontal projection” (K. J. Tennessen), or stated more simply, there isn’t a “horn” on its face-head.

Prince Baskettail (Epitheca princeps) | exuvia (dorsal–lateral)

The D. transversa exuvia also features lateral spines and mid-dorsal hooks, as shown below. Notice the mid-dorsal hooks aren’t as cultriform as E. princeps. In contrast to the E. princeps exuvia, notice the prominent “horn” on the face of the D. transversa exuvia. It’s all about the “horn.”

Stream Cruiser (Didymops transversa) | exuvia (dorsal)

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

Related Resources

Macromiidae – It’s all about the “horn.”
Test shots: Didymops transversa exuvia
Exuvia from Family Macromiidae (Cruisers)
Epitheca princeps exuvia, posted on 06 September 2018.
Epitheca princeps exuvia, posted on 05 March 2017.

Tags: Didymops transversa, Epitheca princeps, exuvia, Family Corduliidae (Emeralds), Family Macromiidae (Cruisers), Prince Baskettail dragonfly, Signs of Wildlife, Stream Cruiser dragonfly

This entry was posted on September 28, 2021 at 4:00 am and is filed under dragonflies, education, How To, macro photography, natural science, wildlife photography. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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