Aquatic Insects of Michigan

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

Phanogomphus (Gomphidae) (Part of Common Clubtails) of Michigan - Identification

Formerly a part of the Gomphus (sensu lato) group, recent work (Ware et al. 2017) has supported the idea that Carle's (1986) subgeneric grouping merits generic ranking, and that species of Gomphus (sensu stricto) are an Eurasian grouping. Adults have variable characters but usually have well-developed drak striping on the thorax, with the front margin of the costa yellowish, with a yellow or pale green face, and distinct veination. Immatures are shallow borrowers in silt of lentic and lotic environments, and are characterized by well-developed burrowing hooks on the pro- and mesotibiae, nearly parallel-sided prementum, a labial palp ending in a well-developed hook, and more rounded and distally pointed abdomen than nymphs of Hylogomphus and Gomphurus.

(Taxonomic References: Carle 1986, Walker 1958, Needham et al. 2014, Tennessen 2019)

Adults

1a	a. Males	2
1b	b. Females	6
2a(1a)	a. Cerci in dorsal view each with a lateral spine or moderate lateral angulation	3
2b	a. Cerci in dorsal view without lateral spines or angulation, at most with a low, rounded lateral swelling	5
3a(2a)	a. Coloration not dark, and/or with dark and pale areas strongly contrasting, metepisternal pale stripes well-developed	Phanogomphus graslinellus (Walsh)
	b. Ab7-9 moderately expanded, ventrolateral flange on Ab8 >0.2mm wide
	also: Tibiae and tasi entirely black or very dark brown except pale on basal 4/5 or less of tibial extensor surfaces; anterior hamules each smoothly curved, not strongly bent anteriorly near the midlength; anterior lamina in lateral view trunccate or rounded apically; cerci in lateral view each with a ventromedial flange forming a small, rounded or somewhat angulate prominence at 4/5 or more of cercus length
3b	a. Coloration dark, and with dark and pale areas not strongly contrasting, metepisternal pale stripes absent or vestigial	4
	b. Ab7-9 hardly expanded, ventrolateral flange on Ab8 usually no more than 0.2mm wide
4a(3b)	a. Cerci, in dorsal view, each with a prominent lateral tooth, in lateral view with a prominent, stout, ventral spine or tooth	Phanogomphus spicatus (Hagen)
	b. Posterior hamules each with a distinct shoulder
4b	a. Cerci, in dorsal view, each with a lateral angulation but without a distinct tooth, in lateral view without a ventral spine or tooth	Phanogomphus lividus (Selys)
	b. Posterior hamules each without a distinct shoulder
5a(2b)	a. Metatibiae entirely black	Phanogomphus quadricolor (Walsh)
	b. Anterior hamules each with a long, flacate terminal hook
	c. Posterior hamules each without a distinct shoulder
	d. Cerci, in lateral view, each with a small ventral tooth at about 2/3 its length
5b	a. Metatibiae with extensor surfaces pale	Phanogomphus exilis (Selys)
	b. Anterior hamules each with only a short, spine-line terminal hook
	c. Posterior hamules with a distinct shoulder
	d. Cerci, in lateral view, without ventral teeth
6a(1b)	a. Metatibiae entire black	Phanogomphus quadricolor (Walsh)
	also: Small lateral spines present on vertex near margin of eye, generally appressed to the surface of cranium; interpleural dark stripe well-developed; subgenital plate with lobes directed downward at approximately right angles to Ab9 sternum
6b	a. Metatibiae with at least the extensor surfaces pale	7
7a(6b)	a. Subgenital plate nearly 1/3 length of Ab9 sternum, or longer, apex of each lobe acute	Phanogomphus spicatus (Hagen)
	b. Posterior surface of occiput markedly trilobed
7b	a. Subgenital plate no more than 1/5 the length of Ab9 sternum, apex of each lobe usually blunt	8
	b. Posterior surface of occiput usually not markedly trilobed
8a(7b)	a. Middorsal stripe of nearly uniform width	Phanogomphus graslinellus (Walsh)
	b. Subgenital plate about 1/8 the length of Ab9 sternum
	also: Tibiae and tarsi entirely black or very dark brown except pale on the basal 4/5 or less of tibial extensor surfaces; lobes of subgenital plate broadly rounded distally, median notch relatively wide, more than 45°
8b	a. Middorsal dark stripe markedly widened anteroventrally	9
	b. Subgenital plate variable
9a(8b)	a. Subgenital plate about 1/5 the length of Ab9 sternum, its lobes each as long as wide	Phanogomphus exilis (Selys)
	b. Vertex with small, acute, dorsolaterally-directed lateral spines
9b	a. Subgenital plate about 1/10-1/7 length of Ab9 sternum, its lobes each wider than long	Phanogomphus lividus (Selys)
	b. Vertex with small, acut, more or less erect lateral spines

Mature Nymphs

1a	a. Ratio of Ab9 ventral length : basal width 0.9-2.0	Phanogomphus quadricolor (Walsh)
	b. Ab8 usually lacking a middorsal hook or prominence
	also: Ratio of Ab10 ventral length : basal width <1.2; Ab9 posterolateral spine length, in dorsal view, >0.4x that of Ab10 lateral margin; median tooth of ligula singular, small to absent
1b	a. Ratio of Ab9 ventral length : basal width 0.5-0.9	2
	b. Ab8 usually bearing a small middorsal hook or prominence
2b(1b)	a. Lateral margins of Ab8-9 usually without stout spinules, appearing smooth	Phanogomphus spicatus (Hagen)
	b. Posterolateral spines only on Ab7-9
	c. Ab8 posterior margin without a middorsal prominence, at most vestigial
	also: Ratio of Ab9 posterolateral spine length : Ab10 ventral length 0.3-0.4; length of anterolateral sclerite on venter of Ab8 2.40-2.72x its basal width
2b	a. Lateral margins of Ab8-9 usually with stout spinules, appearing finely serrate	3
	b. Posterolateral spines on Ab6-9
	c. Ab8 posterior margin with well-developed middorsal prominence
3a(2b)	a. Lateral margins of Ab6-7 with conspicuous spinules	Phanogomphus graslinellus (Walsh)
	b. Ab9 with a median "ridge" abruptly rounded
	c. Ab4 with a middorsal hook
	d. Ratio of Ab10 ventral length : width =<0.83
3b	a. Lateral margins of Ab6-7 usually devoid of spinules	4
	b. Ab9 with a median broadly rounded
	c. Ab4 without a middorsal hook
	d. Ratio of Ab10 ventral length : width =>0.83
4a(3b)	a. Ant3 length usually >1.45 mm	Phanogomphus lividus (Selys)
	b. Ab5-9 tergites appear nearly smooth at magnification 25x
	c. Metathoracic femur length 5.4-6.3 mm
	d. Median lobe of prementum distinctly convex
	e. Epiproct length 1.20-1.45 mm
	f. Maximum abdominal width 7.5-8.6 mm
4b	a. Ant3 length usually <1.45 mm	Phanogomphus exilis (Selys)
	b. Ab5-9 tergites appearing granulate at magnification 25x
	c. Metathoracic femur length 4.4-5.6 mm
	d. Median lobe of prementum distinctly convex
	e. Epiproct length 1.05-1.20 mm
	f. Maximum abdominal width 5.5-7.0 mm

Carle FC. 1986. The classification, phylogeny and biogeography of the Gomphidae (Anisoptera). I. Classification. Odonatologica 15: 275–326.
Needham JG, Westfall MJ, May ML. 2000. Dragonflies of North America, Revised Edition. Scientific Publishers, Gainesville, Florida, USA. xv + 939 p.
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.
Tennessen KJ. 2019. Dragonfly nymphs of North America: An Identification Guide. Springer International Publishing, Cham, Switzerland: xiv + 620 p.
Walker EM. 1958. The Odonata of Canada and Alaska, Volume 2. University of Toronto Press: Toronto, Ontario, Canada. xii + 318.
Ware JL, Pilgrim EM, May ML, Donnelly TW, Tennessen KJ. 2017. Phylogenetic relationships of North American Gomphidae and their close relatives. Systematic Entomology (in print).

Page created: July 17, 1998 - Last updated: April 24, 2020