Ophiogomphus westfalli spec. nov. from the Ozark region of Arkansas and Missouri, with a key to the Ophiogomphus species of eastern North America (Anisoptera: Gomphidae)

O westfalli sp. n. (Q holotype, $ allotype: Caddo River, Montgomery Co., Arkansas, USA; deposited in Florida State Coll, of Arthropods, Gainesville) is described and figured for both the adult and larval stages. It is compared with O. rupinsulensis (Walsh) from which it is distinguished by the reduced dark colors on the thorax, and by structural differences in the male anal appendages and the female occiput. The distribution of these two species in Arkansas and Missouri is discussed, and O. rupinsulensis is removed from lists of both states. A key is presented to the adults of the 12 species of Ophiogomphus now known from eastern North America.