Stylogomphus sigmastylus sp. nov., a new North American dragonfly previously confused with S. albistylus (Odonata: Gomphidae)

Abstract

Previously, the genus Stylogomphus in North America was believed to contain only a single species, S. albistylus. We present evidence for recognizing a second species, S. sigmastylus sp. nov.: holotype ♂, allotype ♀: Big Swan Creek, near Gordonsburg Church of Christ, Lewis County, Tennessee, 11 June 1990, C. Cook leg., deposited in the Florida State Collection of Arthropods. The biology, distribution and morphology of the new species are described, and S. albistylus is re-described and figured to differentiate between the two species. S. sigmastylus sp. nov. males primarily differ from S. albistylus by having a more divaricate epiproct with widely flaring apices and a “U” shaped median cleft; shorter, thicker cerci basal of ventrolateral denticles with width and length approximately equal; ventrolateral denticles located at ca 1/3 appendage length; and posterior hamules with apex carinae thicker. The new species occurs mainly west of the Appalachian Mountains, predominantly in Arkansas, Kentucky, Missouri and Tennessee. The two species are parapatric in an area from southwestern Virginia south to North Carolina, west to northwestern Alabama and north to south-central Kentucky.

Keywords: Odonata, dragonfly, Gomphidae, Octogomphini, Stylogomphus, hybridization, morphology, new species, systematic, North America

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