Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
[cite:478365]
checklist (based on(1)) with very good habitus illustrations of selected spp.
http://mississippientomologicalmuseum.org.msstate.edu/Researchtaxapages/Hydrophilidae/Hydrophilidae.species.list.html

text
The publication by Testa & Lago this website is based on has a full text copy on the Internet Archive

Link no longer working
This seems to be current: http://mississippientomologicalmuseum.org.msstate.edu/Researchtaxapages/Hydrophilidae/Hydrophilidae_Introduction.html