Variation in CanadianGomphus fraternus(Odonata: Gomphidae) in relation to the recognition of subspeciesmanitobanus

Abstract

AbstractSeven characters were evaluated in 146 specimens ofGomphus fraternus(Say), including both subspecies,G. f. fraternus(Say) andG. f. manitobanusWalker, to clarify their circumscription and geographic occurrence in Canada. Specimens corresponding to subspeciesmanitobanuswere all from the Assiniboine and Red rivers and formed a discrete group in a principal components analysis, supporting their taxonomic recognition. Their distribution in Canada suggests a separation of subspecies near the boundary of the prairie ecozone in central southern Manitoba. In subspeciesfraternusthe extensor surfaces of the tibiae are largely black, with pale areas often lacking and rarely up to 50% of the segment length. Similarly the dorsal surface of abdominal segment 9 is largely black. If there is a pale area, it is <1 mm long. In subspeciesmanitobanusthe extensor surfaces of the tibiae have pale markings on ≥50% of their lengths and the dorsal surface of abdominal segment 9 has a dorsal yellow spot ≥1.4 mm long. Widespread dragonflies in western North America are paler in drier climates and the increased pale colouration in the western subspeciesmanitobanuscorresponds to this trend. Currently known only from Manitoba, subspeciesmanitobanusmay occur in prairie habitats of the Midwestern United States, based on reports of pale individuals in that region.