2 individuals (photos 1-5 body 3.3 mm and 6-9 body 3.9 mm)
I found this large black pupa on the concrete part of the riverbed. I don't know how it got there. It was a bit muddy. Photos 2-4 show the spiracles. It was hard to the touch.
I collected it, but it never emerged.
Photos 4-8 and 11 were brightened in Photoshop.