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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Phanogomphus (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. 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

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. Lateral spines present on Ab7-9 only Phanogomphus spicatus (Hagen)
also: Lateral edge of Ab9, including the lateral spine, >3.3mm long, the lateral spine about 1/3 the length of the lateral edge of Ab10
1b a. Lateral spines present on Ab6-9 2
 
2b(1b) a. Midventral length of Ab9 equal to its basal width Phanogomphus quadricolor (Walsh)
b. Teeth of labial palps all very low and blunt
2b a. Midventral length of Ab9 less than its basal width 3
b. Teeth of labial palps well-developed, somewhat angulate
 
3a(2b) a. End hook of each labial palp little, if at all, larger than the next adjacent tooth Phanogomphus graslinellus (Walsh)
b. Middorsal length of Ab9 shorter, not more than 3/5 its basal width
also: Dorsal hooks of abdomen with small erect or hook-like projections on Ab4-9
3b a. End hook of each labial palp distinctly larger than the next adjacent tooth 4
b. Middorsal length of Ab9 longer, usually at least 2/3 its basal width
 
4a(3b) a. Median lobe of prementum straight or very slightly convex Phanogomphus lividus (Selys)
b. Very small dorsal hook usually present on Ab4
c. Larger species, total length of mature nymph usually >30mm
 
4b a. Median lobe of prementum distinctly convex Phanogomphus exilis (Selys)
b. Usually no dorsal hook on Ab4
c. Smaller species, total length of mature nymph <27mm
 
 

References

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.
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 20, 2017