The Michigan species of this large group of dragonflies usually are grouped into three distinctive subgenera: Gomphus, Gomphurus and Hylogomphus. Larvae occupy a variety of habitats, burrowing into (usually soft) substrates of lakes, ponds, streams and rivers.
Earlier workers usually grouped species of Gomphus, Gomphurus and Hylogomphus as well as Stylurus and Arigomphus into a taxonomic "basket" called Gomphus, although most recognized distinctive groups warranting full generic rank. Needham and Westfall's (1955) organization of the North American species into five distinctive groupings provided some clarity, but currently no monophyletic grouping has been agreed upon. Most authors have been satisfied with the generic elevation for but two groups - Arigomphus and Stylurus (see each respective page for a brief discussion of their generic elevation). Shortly after Needham and Westfall's 1955 book, Walker (1957) published an analysis of adult genitalia in Gomphus. He concluded that only three subgenera formed natural groupings - Arigomphus, Gomphurus, and Stylurus, whereas Hylogomphus formed a distinct group around the species Gomphus brevis, and with the remaining species of Gomphus sensu lato lacking distinct, monophyletic relationships.
More recent work by Louton (1982) and Carle (1982, 1986, and 1995) attempted to find more natural groupings within Gomphurus and Gomphus sensu lato groups. Stenogomphurus and Gomphurus (Carle 1982) arose from two distinctive species groups from within Gomphurus, and Gomphus and Phanogomphus (Carle 1986) substituted for Needham and Westfall's Hylogomphus and Gomphus sensu lato, respectively. May and Carle (1996), who give a good summary of the debate, also point that Hylogomphus may not be considered a "good" taxon because Needham and Westfall did not designate a type-species. Indeed, Garrison (1991) considers this a synomyn of Gomphus. The "conservative" method is to recognize Arigomphus and Stylurus as valid genera, whereas Gomphus (or Phanogomphus), Gomphurus (or Gomphurus and Stenogomphurus) and Hylogomphus (or Gomphus if Phanogomphus is recognized instead of Gomphus sensu lato) are delegated as subgenera of Gomphus.
This has all been resolved with the work by Ware, et. al (2016), with a comprehensive study involving molecular phylogeny of the Gomphidae. As indicated above, there are now the valid genera Phanogomphus, Stenogomphurus, Gomphurus, and Hylogomphus. Gomphus does not occur in the western hemisphere.
Links on the biology and ecology of larval
Biology and habitat info on Gomphus apomyius >>http://www.hsrl.rutgers.edu/apomyius.html
Brief habitat notes (Cumberland/Cape May Co., NJ, USA) on G. exilis and G. apomyius >>http://www.hsrl.rutgers.edu/cumb.cape.txt
Brief habitat notes from Ottawa, Ontario >>http://www.ncf.carleton.ca/~bf250/odonata.html
Not biology, but if flyfishing's your bag... >> http://bcadventure.com/adventure/angling/flies/dragonfly/nymph.htm
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Michigan Species List of Gomphini
1a. Middorsal length of Ab9 equal to, or greater than, half its basal width (fig); length of Ab10 ca. 0.66x-0.75x its width (fig) - Phanogomphus, 2
length of Ab9 less than half its basal width (fig); length of Ab10
< 0.50x its width (fig) - 6
2a(1a). Well developed lateral spines on Ab7-9, very minute if present on 6 (fig); no vestigial dorsal hook on Ab9 (fig); principally lentic - Phanogomphus spicatus
developed lateral spines on Ab6-9 (fig); Ab9 with at least a
vestigial middorsal hook (fig); middorsal length of Ab9 usually less
than its width (fig) - 2
3a.(1b). Middorsal length of Ab9 about equal (>0.93x) to its basal width (fig); middorsal hook only on Ab9 - Phanogomphus quadricolor
length of Ab9 less than 0.9x (<0.88x) its basal width (fig);
middorsal hook at least on Ab8 and Ab9 - 3
Back to previous couplet (1); Back to beginning of subgenus key
4a.(3b). End hook of palpal lobe not much longer than the tooth adjacent to it (fig); Ab9 markedly wide, its middorsal length about 0.55x its basal width (fig); middorsal hooks on Ab2-9 (fig) - Phanogomphus graslinellus
4b. End hook
of palpal lobe produced, markedly longer than the tooth adjacent to
it (fig); Ab9 narrower than above, its middorsal length about 0.75x
(0.68-0.88x) its basal width (fig); middorsal hooks absent from Ab2-3
(fig) - 4
Back to previous couplet (2); Back to beginning of key; Back to beginning of subgenus key
5a.(4b) Mature larva large, > 29 mm in total length; edge of median lobe of labium straight or only slightly convex (fig); with at least small middorsal hooks on Ab6-7 (fig); epiproct longer (>1.10x) than middorsal length of Ab10; Ab10 distinctly wider than long (fig); - Phanogomphus lividus
larva smaller, <28 mm in total length; edge of median lobe of
labium convex (fig); middorsal hooks only on Ab8-9 (fig); epiproct
shorter than middorsal length of Ab10; Ab10 longer than above, nearly
square in outline (fig) - Phanogomphus exilis
Back to previous couplet (3); Back to beginning of key; Back to beginning of subgenus key
6a.(1b). Lateral spines of Ab9 apart from Ab10, about same length as those on Ab8 (fig); abdomen not markedly dorsoventrally compressed (fig) - Hylogomphus, 7
spines of Ab9 close to Ab10, markedly longer than those on Ab8 (fig);
abdomen appears dorsoventrally flattened (fig) - Gomphurus,
Back to previous couplet (1)
7a(6a). End hook of palpal lobe about 2.0x the length of the adjacent tooth (fig); small vestigal middorsal hook on Ab9 (fig) - Hylogomphus adelphus
7b. End hook
of palpal lobe > 2.0x the length of the adjacent tooth (fig); no
middorsal hook on Ab9 (fig) - Hylogomphus viridifrons
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8a(6b). Apical margin of median lobe of prementum deeply concave (fig) - Gomphurus lineatifrons
margin of median lobe of prementum straight or slightly convex (fig)
9a.(8b). End hook of lateral lobe of labium strongly incurved, extending far past apex of the truncate, 3 to 4 lateral teeth next to it (fig) - Gomphurus vastus
9b. End hook
of lateral lobe of labium much less curved or straight, at best
barely extending past the 6 lateral teeth next to it (fig) -
Back to previous couplet (1)
10a(9b). Length of prementum long, 1.32-1.35x long as wide (fig); Ant3 long, length about 2.6x that of Ant1-2 combined (fig); lateral spines of Ab6-7 strongly divergent - Gomphurus ventricosus
10b. Length of
prementum shorter, < 1.10x long as wide (fig); Ant3 shorter,
length about 1.5x that of Ant1-2 combined (fig); lateral spines of
Ab6-7 only slightly divergent (fig) - Gomphurus fraternus
Back to previous couplet (9); Back to beginning of key
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Calvert, P. P. 1921. Gomphus dilatatus, vastus, and a new species, lineatifrons (Odonata). Transactions of the American Entomological Society 47:221-232.
Carle, F. L. 1986. The classification, phylogeny, and biogeography of the Gomphidae (Odonata: Anisoptera). I. Classification. Odonatologica 15(3):275--326.
Garrison, R. W. 1991. A synonymic list of the New World Odonata. Argia 3(2):1-30.
Hine, J. S. 1901. A new species of Gomphus and its near relatives. Ohio Naturalist 1(4):60-61.
Huggins, D. G. and G. L. Harp. 1985. The nymph of Gomphus (Gomphurus) ozarkensis Westfall (Odonata: Gomphidae). Journal of the Kansas Entomological Society 58(4):656-661.
Louton, J. A. 1982. Lotic dragonfly (Anisoptera: Odonata) nymphs of the Southeastern United States: identification, distribution and historical biogeography. Unpublished Ph.D. thesis, The University of Tennessee, Knoxville. 357 pp.
Louton, J. A. 1983. The larva of Gomphurus ventricosus (Walsh), and comments on relationships within the genus (Anisoptera: Gomphidae). Odonatologica 12(1):83-86.
May, M. L., and F. L. Carle. 1996. An annotated list of the Odonata of New Jersey, with an appendix on nomenclature in the genus Gomphus. Bulletin of American Odonatology 4(1):1-35.
Needham, J. G. and M. J. Westfall, Jr. 1955. A Manual of the Dragonflies of North America (Anisoptera). University of California Press: Berkeley, California. xii + 615 pp.
Say, T. 1839. Descriptions of new North American neuropterous insects and observations on some already described by (the late) Th. Say. Journal of the Academy of Natural Science of Philadelphia 8:9-46.
Selys-Longchamps, M. E. de. 1854. Synopsis des Gomphines. Bulletin de l'Académie royale des Sciences de Belgique 21:23-114.
Walker, E. M. 1957. The affinities of the North American species of Gomphus as revealed by the genitalia (Odonata, Gomphidae). Contributions of the Royal Ontario Museum, Division of Zoology and Palaeontology, No. 46, 24 pp.
Walker, E. M. 1958. The Odonata of Canada and Alaska, Vol. 2. University of Toronto Press: Toronto. xii + 318.
Walsh, B. D. 1862. List of the Pseudoneuroptera of Illinois contained in the cabinet of the writer, with descriptions of over forty new species, with notes on their structural affinities. Proceedings of the Academy of Natural Sciences Philadelphia 14:361-402.
Ware, J.L., E. Pilgrim, M.L. May, T.W. Donnelly and K. Tennessen. 2016. Phylogenetic relationships of North American Gomphidae and their close relatives. Systematic Entomology DOI:10.1111/syen.12218