Aquatic Insects of Michigan

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

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

[under construction]

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. Gomphurus are the largest of the Gomphus complex, and adults are noted for the great widening of abdominal segments 7-9, with bold striping on the thorax. Nymphs are visibly similar to Hylogomphus but are larger, have a more dorsoventral compressed and wide body form, and have a middorsal groove on the middle abdomen segments.

(Taxonomic References: Carle 1986, Paulson 2011, Needham et al. 2014, Walker 1958)

Adults

1a	a. Prominent dark crossband along the frontoclypeal suture	2
1b	a. No prominent dark crossband along the frontoclypeal suture, although suture may appear as a dark hairline	3
2a(1a)	a. Dark frontoclypeal band at most about as wide as the median ocellus	Gomphurus lineatifrons (Calvert)
	b. Subgenital plate of female with apices blunt
	also: Hindwing <38mm; interpleural dark stripe incomplete; in lateral view, poasterior margin of penis vesicle nearly straight in middle 1/2 or more; penile flagella long; subgenital plate about 1/2 as long as Ab9 sternum, constricted near base
2b	a. Dark frontoclypeal band wider than the median ocellus	Gomphurus vastus (Walsh)
	b. Subgenital plate of female with apices acut
	also: Ab9 lateral margins entirely yellow; hingwing <34mm; in lateral view penis vesicle about 3/4 as long basally as high; subgenital plate of female more than 1/2 as long as Ab9 sternum
3a(1b)	a. Interpleural dark stripe complete, metepisternal pale stripe not confluent with mesepimeral pale stripe	Gomphurus externus (Hagen)
	b. Extensor surface of tibiae generally with a pale yellow basal stripe
	c. Third femora of female usually without a yellow stripe
3b	a. Interpleural dark stripe incomplete, metepisternal pale stripe confluent with mesepimeral pale stripe above the metathoracic spiracle	4
	b. Extensor surface of tibiae generally without a pale yellow basal stripe
	c. Third femora of female usually with a yellow strip
4a(3b)	a. Dorsum of Ab8 without a yellow basal spot, or with only a minute spot	Gomphurus ventricosus (Walsh)
	b. Penis vesicle of male, in lateral view, not higher than its basal length, the anterior surface with a cup-like excavation
	c. Penile flagella of male variable
	d. Posterior hamules of male each usually with shoulder not visible in strict lateral view
	e. Subgenital plate of female <1/2 length of Ab9 sternum
4b	a. Dorsum of Ab8 with a distinct, triangular yellow basal spot, 1/5 segment length	5
	b. Penis vescile of male, in lateral view, higher than its basal length, the anterior surface with a V-shaped cleft
	c. Penile flagella of male long
	d. Posterior hamules of male each usually with shoulder visible in strict lateral view
	e. Subgenital plate of female at least 1/2 length of Ab9 sternum
5a(4a)	a. Dorsum of Ab9 with yellow spot	Gomphurus crassus (Hagen)
	b. Male cerci each with a distinct lateral ridge ending in a tooth
	c. Female vertex without erect horns behind ends of postocellar ridge
	d. Female occiput without median conical tooth
5b	a. Dorsum of Ab9 without a yellow spot	Gomphurus fraternus (Say)
	b. Male cerci each without a distinct lateral ridge ending in a tooth
	c. Female vertex with erect horns behind ends of postocellar ridge
	d. Female occiput with a median conical tooth

Mature Nymphs

1a	a. Median lobe of prementum deeply concave	Gomphurus lineatifrons (Calvert)
1b	a. Median lobe of prementum straight or convex	2
2a(1b)	a. Labial palps with 6-9 teeth extending toward apex in a straight line or shallow curve, end hook little larger than the next adjacent tooth	3
2b	a. Labial palps with 2-5 teeth curving sharply toward a hooked apex, end hook much larger than the next adjacent tooth	5
3a(2a)	a. Length of Ab9 lateral spines about 1.5x the middorsal length of Ab10	Gomphurus externus (Hagen)
	also: Median lobe of prementum without a median tooth; total length at least 30mm
3b	a. Length of Ab9 lateral spines about 1.25x the middorsal length of Ab10	4
4a(3b)	a. Median lobe of prementum straight	Gomphurus ventricosus (Walsh)
	b. Lateral spines of Ab6-7 strongly divergent from lateral margins of respective segment
4b	a. Median lobe of prementum slightly convex	Gomphurus fraternus (Say)
	b. Lateral spines of Ab6-7 weakly divergent from lateral margins of respective segment
5a(2b)	a. Lateral spines of Ab9 shorter, about equal to the middorsal length of Ab10	Gomphurus crassus (Hagen)
	also: Labial palps each with at least 2-3 small teeth in addition to the large end hook
5b	a. Lateral spines of Ab9 longer, about 1.25x the middorsal length of Ab10	Gomphurus vastus (Walsh)
	also: Margin of median lobe of prementum straight; total length no more than 32mm

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.
Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 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: February 26, 2017