Hey John. Just from eyeballing the length of the breathing tube of the bug in the picture you posted with the bug I found, I'd say C. rastricornis is just about right.

I've replaced one of the shots I originally posted with another, showing a different view of the breathing tubes. I would note that, as apparent in that view, the bug's "right-hand" breathing tube is about half the length of the left. That right-hand tube ends in what appears to be a blackened stump. The tube may have been damaged at the time I collected it, or it may be an older injury (which would perhaps be more likely, given the fact that the stump is black). In this photo, the blackened stump is just touching the water/air boundary. The length of the left-hand tube appears to be a little over twice that of the right-hand tube.

I replaced the original dorsal view that I posted with another version of that photo, only cropped to show more of the middorsal stripe.

Thanks for the ID. -- Cat