Helichus confluentus Hinton, 1935. On debris and beneath rocks usually 

 in upland or mountain streams of western Texas, New Mexico, and 

 Arizona, but with a disjunct population in the mountains of northern 

 Georgia (Rabun Bald) . 



Helichus fastigiatus (Say, 1824) . Under rocks in streams from Florida 

 to Maine and Canada, west to Illinois, eastern Kansas and Oklahoma. 



Helichus immsi Hinton, 1937. On debris and under rocks in streams from 

 western Texas to California, often abundant. 



Helichus lithophilus (Germar, 1824) . Under stones or on submerged wood 

 in streams from Florida to Canada and west to Wisconsin, Iowa, cen- 

 tral Oklahoma and Texas. 



Helichus productus LeConte, 1852. On debris and under rocks in valley 

 and foothill streams of central and southern California. 



Helichus striatus LeConte, 1852. On debris and under rocks in cool 

 streams from South Carolina to Quebec, west to California and 

 British Columbia. 



Helichus striatus foveatus LeConte, 1852. On debris and under rocks in 

 western streams up to elevations well above 8,000 feet, from 

 Arizona and Califomi? to British Columbia. 



Helichus suturalis LeConte, 1852. On debris and under rocks in all sorts 

 of streams from warm, muddy, lowland rivers to mountain brooks well 

 above 8,000 feet from central Oklahoma and Texas west to Utah and 

 California and south to Guatemala; often abundant and frequently the 

 only dryopoid in lowland southwestern streams. 



Helichus triangularis Musgrave, 1935. On debris and under rocks in small 

 mountain streams from the Chisos and Davis Mountains of Texas to the 

 Chiricahua and Huachuca Mountains of Arizona. 



Genus Pelonomus Erichson, 1847 



Pelonomus obscurus LeConte, 1852. Not a "riffle" beetle. On aquatic 

 plants and debris in swamps and ponds (though most often taken at 

 lights) from Florida to Texas and north to Illinois. 



Family LIMNICHIDAE (Thomson, 1860) 



Subfamily Limnichinae 



Genus Limnichus Latreille, 1829 

 Many species have been described, but none are known to be aquatic, 

 although the adults may be found in damp places such as stream 

 margins throughout much of the United States. 



Genus Lutrochus Erichson, 1847 



Lutrochus arizonicus Brown and Murvosh, 1970. Larvae in calcareous en- 

 crustation of submerged rocks, etc.; adults usually at or just above 

 water line on the downstream side of rocks or wood projecting from 

 the water in riffles of streams in central Arizona. 



Lutrochus laticeps Casey, 1893. Larvae and adults as above in streams 



of high calcium content from Maryland to Michigan and eastern Oklahoma. 



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