Narpus arizonicus (Brown, 1930). In rapid streams of the White Moun- 

 tains of eastern Arizona. (This may be but a variant of N. concotor') 



Narpus concotor (LeConte, 1881). In clear, rapid, cool or cold streams 

 of western states from New Mexico to California and north into 

 Canada. 



Genus Neocyltoepus Brown, 1970 



Neooylloepus boeseli Brown, 1970. In gravel and rocks of rapids in 



Devil's River northwest of Del Rio, Texas and West Clear Creek east 

 of Camp Verde, Arizona. 



Genus Eeoelmis Musgrave, 1935 



Neoelmis oaesa (LeConte, 1874). In gravel and under rocks in riffles of 

 clear streams with a high calcium content in south-central and south- 

 western Texas, the Arbuckle Mountain region of south-central Oklahoma 

 and southeastern New Mexico. 



Genus Optioservus Sanderson, 1954 



Optioservus ampliatus (Fall, 1925). In riffles of gravelly or rocky, 



clear streams from Virginia northward into Canada, Relatively 



tolerant of sewage and chlorides. 

 Optioservus canus Chandler, 1954. Known only from Chalone Creek in 



Pinnacles National Monument of west central California. 

 Optioservus cryophilus (Musgrave, 1932) . On moss-covered stones in 



fast, spring-fed brooks of the Great Smoky Mountains. 

 Optioservus divergens (LeConte, 1874) . In gravelly or rocky riffles of 



clear streams from New Mexico to California and north into Canada. 

 Optioservus fastiditus (LeConte, 1850) . In gravelly or rocky riffles or 



on wood in fast streams in upper New York and from Michigan to 



Minnesota. 

 Optioservus immunis (Fall, 1925). In gravelly or rocky streams of 



Connecticut, New Jersey, and Pennsylvania. (Records from Georgia 



and Tennessee may represent 0. cryophilus, which greatly resembles 



0. immunis) . 

 Optioservus ovalis (LeConte, 1863) . In gravel or among moss-covered 



stones in clear, riffly streams from North Carolina north to Vermont 



and west to Alabama and Ohio. 



Optioservus ozarkensis Collier, n. sp. (see page 13) (Fig. 83) 



Type locality: Holotype, male. Roaring River State Park, Cassville, 

 Missouri. Collected 30 December 1968 by Joe E. Collier. 



Location of Type: Holotype, male. Department of Entomology, Fisheries, 

 and Wildlife, University of Minnesota; four paratypes. Snow 

 Entomological Museum, University of Kansas, Lawrence, Kansas; ten 

 paratypes will be deposited in California Academy of Sciences 

 Collection. 



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