This is definitely a Lasioglossum (Chilalictus) species. It may be L. brunnesetum, which is a rather small species. An estimate of the body length might help.
Thanks Michael. The photo is 4 yrs old and I wasn't so interested in entomology then so didn't note lengths. I have to try to remember, and might not be accurate. Looking at the vegetation in the uncropped shot I'd say it's a small bee.