Of the seven North American species placed in this group, three have been reliably recorded in Michigan (see maps below). A single specimen for A. submedianus (Williamson, 1914), quoted from Hagen (1885) and apparently listed as Gomphus pallidus, a species normally found in the southeastern USA, is missing and is now thought not to be reliable, and thus has been removed from the state list. Previously considered a subgenus of Gomphus (Needham 1897, Needham and Westfall 1955, Walker 1958), this group currently is considered distinct enough to merit generic status (e.g., Knoff 1977, Westfall and Tennennsen 1996). Larvae are easily recognizable from other gomphids by the elongated abdominal segment 10, the long laterally-flattened spines of abdominal segment 9, and the large, incut teeth of the labium's lateral lobes.
Larvae usually borrow into loose, fine substrates in sluggish sections of lakes and streams. Walker (1958) notes that larvae of A. villosipes prefer substrates "unchoked" with vegetation with soft muddy bottoms, whereas larvae of A. cornutus and A. furcifer tended to frequent benthic areas with at least some aquatic vegetation. Emergence for these species generally ranges from very late May through the first half of June.
WWW-Links concerning the ecology and biology of
Brief notes on larval habitat from Houston, Texas area >>http://www.io.com/~pdhulce/dragon2.html
Brief notes on habitat from NE USA >>http://www.hsrl.rutgers.edu/gomph.gui.html
1a. Lateral spines of abdominal segment 9 about equal or greater than 0.4x the mid-dorsal length of abdominal segment 10 (picture) - A. villosipes
spines of abdominal segment 9 about equal to or less than 0.2x the
mid-dorsal length of abdominal segment 10 (picture) - 2
2(1). Large, larval length greater than 38 mm; epiproct less than length of paraproct (picture) - A. cornutus
2a. Small, larval length no greater than 35 mm; epiproct about equal to length of paraproct (picture) - A. furcifer
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Hagen, H. A. 1885. Monograph of the earlier stages of the Odonata. Sub-families Gomphina and Cordulegastrina. Transactions of the American Entomological Society 12:249-291.
Knopf, K. W. 1977. Protein variation in Gomphus (Odonata: Gomphidae). Unpublished Ph.D. thesis, University of Florida, Gainesville. vi + 107 pp.
Needham, J. G. 1897. Preliminary studies of North American Gomphinae. Canadian Entomologist 29:164-168, 181-186 + 1 pl.
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.
Selys-Longchamps, M. E. de. 1854. Synopsis des Gomphines. Bulletin de l'Académie royale des Sciences de Belgique 21:23-114.
Selys-Longchamps, M. E. de. 1878. Quatrièmes additions au synopsis des Gomphines. Bulletin de l'Académie royale des Sciences de Belgique 46:408-471,658-698.
Tough, J. 1900. A new species of Gomphus. Occasional Memoirs of the Chicago Entomological Society 1:17-18.
Westfall, M. J., and K. J. Tennessen. 1996. Odonata, pp. 164-211, In An Introduction to the Aquatic Insects of North America, 3rd Ed. R. W. Merritt and K. W. Cummins (eds.). Kendell/ Hunt Publishing Company: Dubuque, Iowa.
Walker, E. M. 1958. The Odonata of Canada and Alaska, Vol. 2. University of Toronto Press: Toronto. xii + 318.
Williamson, E. B. 1914. Dragonflies (Odonata) collected in Texas and Oklahoma. Entomological News 25(10):444-454.