This is the first individual of Limonius crotchii that I have ever seen alive. It is not a very commonly seen insect. Jon and I came across it a couple of weeks ago just north of Lake Isabella along the North Fork of the Kern River (just into Tulare County, California). The orange elytra are quite striking and are a lot brighter than in preserved specimens.
It isn't all that big - just about a half inch long (over a centimeter) and it does look similar to other black and orange elaterids. Species of Ampedus can often look similar and even have the double sutures on the prosternum (on the underside of the pronotum). Even the front of the head in L. crotchii looks more like Ampedus than some other Limonius.
A good way to distinguish this beetle, though, is to look at the base of the front legs which are nearly completely closed (meaning they are surrounded by the hypomera). If this sounds all too complex, you can simply take my word for it (fortunately I'm only wrong less than half the time :).
It has been a wet year in many parts of California and the North Fork was very high. We saw several brave river rats floating rapidly along in bright red rafts. The habitat shot is just off the road from the river near an unmarked camping area where we stayed.