ABSTRACT 



An illustrated key is given for all known species of adult dryopoid 

 beetles of the United States which have aquatic stages and might be 

 useful as indicators of water quality. A key is also given to the 

 genera of larvae. For each species the known habitat and range are 

 given. Life histories are briefly outlined and methods for collection, 

 preservation, storage and identification are suggested. Two new 

 species, Optioservus ozarkensis Collier and Optioservus sandersoni 

 Collier, are described. The genera included in the keys are: 

 Chelonariidae- -Chelonarium; Elmidae--Tribe Larini: Lara^ Phanocevus; 

 Tribe Elmini: AmpumixiSj Anayronyx ^ Atractetmis^ Cleptelmis^ CylloepuSj 

 Dubiraphia, Elsianus, Gonietmis, Uetevelmis , Eetevlirrmius , Hexacytloepus ^ 

 Maaronychus, Microoylloepus , NarpuSj NeooylloepuSj Neoelmis^ 

 Optioservus 3 Ordobrevia^ Outirrmius^ Promoresia^ EhiselmiSj Stenelmis , 

 Zaitzevia; Dryopidae- -ZPrzyopSj Hetichus, Pelonomusj Limnichidae-- 

 Limnichinae: Lirrmichus, Lutroohus, Physemus; Cephalobyrrhinae: 

 Throsoinus; Psephenidae--Eubriinae: AcneuSj DiaranopselaphuSj Ectopvia; 

 Eubrianacinae: Eubri-anax; Psepheninae: Psephenus; Ptilodactylidae-- 

 Andhyoteis, AnahytarsuSj Stenocolus. The bibliography includes 

 selected useful references in addition to the literature cited. 



