I’m fairly new here but having fun I must say.
My thought for the day: In many cases, a single species in a given genus is most commonly collected in a particular locality. For example, with water penny beetles in Vermont (and all of the Northeast) we have: Psephenus herricki. There is a different genus, Ectopria, very distinct from Psephenus, also has one species E nervosa. likely to be collected.
What standard do we apply? In the case of the beetles, IDing a larva from a photo works with confidence to genus level but not beyond. Can we use geography to narrow it farther? ANd if so, how certain do we need to be?