Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

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Rhionaeschna Förster, 1909 (Aeshnidae) (Neotropical Darners) of Michigan - Identification

Formerly ascribed as part of Aeshna, species with a midventral tubercle on the first abdominal segment were separated into Rhionaeschnaby von Ellenreider (2003). This genus is principally Neotropical, with two species - R. multiocolor (Hagen, 1861) and R. mutata (Hagen, 1861) - extending northward into eastern North America. R. mutata (Spatterdock Darner) is record from the southern part of the LP, whereas R. multicolor is principally western but extends eastward into several western counties of Wisconsin, and is included in the key below. Our species has been collect from in woodland swamps and bog-margined ponds and poor fens.

(Taxonomic References: Paulson 2011, Needham et al. 2014, von Ellenreider 2003, Walker 1912, 1958)

Adults

1a a. Males 2
1b a. Females 3
 
2a(1a) a. Distance between posterior base of ventral process and base of dorsal crest of cercus larger than distance between it and tip of cercus mutata
b. Ventral tubercle of Ab1 low, about as wide as 3x its height
c. Base of T-spot stem wider than vertex, vertex black with anterior 30% pale
2b a. Distance between posterior base of ventral process and base of dorsal crest shorter than distance between it and tip of cercus multicolor
b. Ventral tubercle of Ab1 high (about as wide as 2x its height)
c. Base of T-spot stem narrower than vertex, vertex pale with posterior 30% black
 
3a(1b) a. Ventral tubercle of Ab1 low, its width about 3x its height mutata
b. Base of stem of T-spot wider than vertex, anterior of vertex half pale, posterior 50% black
c. Outer margin of cercus linear
3b a. Ventral tubercle of Ab1 higher, its width about 2x its height multicolor
b. Base of stem of T-spot narrower than vertex, vertex pale with posterior 30% black
c. Outer margin of cercus slightly convex
 
 

Mature Nymphs

1a a. Lateral spine Ab6 vestigial, or rarely up to 0.25x as long as the distance from the base of the spine to the base of Ab7 multicolor
b. Spine of Ab8 not quite reaching level of base of Ab9
c. Basal width of lateral spine of Ab9 about 0.75x the length of the spine
1b a. Lateral spine Ab6 about 0.40x as long as the distance from the base of spine to the base of Ab7 mutata
b. Spine of Ab8 projecting beyond level of the base of Ab9
c. Basal width of lateral spine of Ab9 about 0.5x the length of the spine
 
 

References

Needham JG, Westfall MJ, May ML. 2014. Dragonflies of North America. The Odonata (Anisoptera) fauna of Canada, the Continential United States, Northern Mexico and the Great Antilles. Third Edition. Scientific Publishers: Gainesville, Florida. xiv + 658.
Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 p.
von Ellenrieder N. 2003. A synopsis of the Neotropical species of 'Aeshna' Fabricius: the genus Rhionaeschna Förster (Odonata: Aeshnidae). Tijdschrift voor Entomologie 146: 67-207.
Walker EM. 1912. The North American dragonflies of the genus Aeshna. University of Toronto Studies, Biological Series, pp. 1-213.
Walker EM. 1958.
The Odonata of Canada and Alaska, Volume 2. University of Toronto Press: Toronto, Ontario, Canada. xii + 318.

Page created: July 17, 1998 - Last updated: February 28, 2017 (EB)