Quite a small mosquito, and quite easy to identify. The only other species in Florida, Ur. lowii, has hindtarsomeres 4,5, and the apical part of 3 pale-scaled. If you need to tell this from Ur. anhydor, the median stripe of iridescent blue scales on the scutum is characteristic of sapphirina.

Here is a link to some more info:http://www.rci.rutgers.edu/~insects/sapp.htm
and images: http://fmel.ifas.ufl.edu/Key/sapphirinaadult.htm