From an eddy in a creek. I keyed it out to Aquarius (Gerris) remigis, based on the following characteristics (which are labeled in the following images):

- Body length comparatively long and narrow; length greater than 11 mm
- Inner margins of eyes concave around middle (1)
- Pronotum dull (2)
- head with narrow, broadly v-shaped pale mark at base (3)
- Antennal segment 1 (4a) subequal to combined length of antennal segments 2-3 (4b)
- Hind tibia (5a) at least 4X length of hind tarsal segment 1 (5b)
- Prominent connexival spines (6)
- Greatest width (across mesoacetabula) greater than or equal to 0.25X body length (7)

I couldn't tell from the ventral shot whether this is a male or a female. How do you tell, anyway?
This is my first post with labelling. Hope it will be useful for identifying other G. remigis. Please let me know if I've made mistakes or need to make any corrections/additions!!! I don't want to contribute misleading information.