John H. Epler, Ph.D. http://bugguide.net/user/view/4507

Identification manual for the water beetles of Florida (Coleoptera: Dryopidae, Dytiscidae, Elmidae, Gyrinidae, Haliplidae, Hydraenidae, Hydrophilidae, Noteridae, Psephenidae, Ptilodactylidae, Scirtidae)
(PDF download 9MB) Keys to all the species (adults and larva) from Florida known to the author. B&W illustrations. Updates and corrections at: http://home.earthlink.net/~johnepler/index.html

Suggest this link might be added to all the aquatic Coleoptera family pages.