palpi four-segmented, red-brown in color; labial palpi red-brown, 



three-segmented; antennae eleven-segmented, reddish-yellow, first 



three segments equal to length of next six. 



Pronotum : Black; sparse yellowish pubescence; very shallow 



punctures; sides very slightly converging toward apex from base, 



carinae extending from base nearly to middle, parallel to lateral 



margin of thorax. 



Elytra : (Fig. 82) Dark red-brown; each elytron containing one 



rounded humeral spot and one elongated apical spot with sutural 



vitta extending from scutellum to apical third of elytra; spots 



and vitta yellow-orange in color. 



Venter : Epipleuron and most of thorax and abdomen covered with 



short grey pubescence; legs reddish-yellow; most of underside just 



slightly darker than legs in color. 



Female: As for male. 



DISTRIBUTION: Arkansas and Oklahoma. 



SPECIMENS EXAMINED: Holotype (male), three paratypes from Washington 

 Co., Arkansas, four paratypes from Ottawa Co., Oklahoma, taken in 

 June 1930 and 1962. 



Optioservus seriatus (LeConte, 1874) . In gravelly or rocky riffles from 



north coastal California to British Columbia and in scattered 

 localities in New Mexico, Utah, and Idaho. 



Optioservus trivittatus (Brown, 1930). In gravel, under rocks, or on 



wood in fast streams from the Great Smoky Mountains north to 



Vermont and Quebec, and in Michigan and Wisconsin. Relatively 

 tolerant of sewage and chlorides. 



Genus Ovdobrevia Sanderson, 1953 



Ordobrevia nubifera (Fall, 1901). In gravel and under rocks of foot- 

 hill streams from California to Washington. 



Genus Oulirrmius Des Gozis, 1886 



Oulirrtni-us latiusculus (LeConte, 1866) . In gravel or under rocks in 

 riffles of clear streams (often very small brooks) from Alabama, 

 eastern Tennessee, and South Carolina northeast to Canada, ranging 

 from cool lowland streams to elevations higher than any of the other 

 local elmids. 



Genus Promoresia Sanderson, 1954 



Pvomoresia elegccns (LeConte, 1852) . In gravel and under rocks in 



riffles of cool streams from the Great Smoky Mountains northeast to 

 lower New England. Promoresia is unusual among members of its sub- 

 family in that it often takes flight when removed from the water, 

 a feature which is characteristic of the Larinae and of Limnichidae 

 and Psephenidae. 



Promoresia tardella (Fall, 1925). In gravel and among moss and rocks of 

 riffles of cool streams in the Great Smoky Mountains and in New 

 England and eastern Canada. 



19 



