A new species of dragonfly, Gomphus (Gomphurus) lynnae spec. nov., from the Yakima River, Washington, with notes on pruinosity in Gomphidae (Anisoptera)

G. lynnae sp.n. ((J holotype, $ allotype: Yakima River, 9 mi. N Benton City, Benton Co., Washington; deposited in Florida State Collection of Arthropods, Florida Department of Agriculture and Consumer Services, Gainesville, Florida) is the only species of Odonata presently known to be restricted to the Columbia River Basin and is the only member of the subgenus Gomphurus known from west of the Rocky Mountains. It is a dark-colored species related to G. exrernus but differing from that species and other Gomphurus in numerous structural and color-pattern features. It is peculiar in having abundant pruinosity on the head, thorax, legs and base of abdomen and is perhaps the most pruinose gomphid. Relationships among the species of Gomphurus are discussed and species pairs suggested. G. lynnae inhabits a large, rocky to muddy river in sagebrush steppe and is known to fly from 2 June to 18 July. It may be theatened because of its restricted range and the considerable human alteration of rivers in the Columbia Basin.