This adult female keyed out to Theridion frondeum (colulus absent, 2 teeth on promargins of cherlicerae, epigyne structure). Found her on the underside of a leaf where she'd fashioned a shelter for herself, but there was no web.

It's a beautiful little spider. I still have her alive and watched her under the microscope for a while. Her heart rate was about 180 bpm! Also, I could see the tracheal spiracal, in front of the spinnerets, pulsating every few seconds. I don't know if this was an opening and closing - couldn't see that much detail (40x is the most I have and this is a very small spider), but the movement was regular. The abdomen is transluscent, almost transparent when viewed ventrally. I shined a bright light into it from the side and was able to see fluids (haemolymph?) flowing and moving around. Very interesting. There's a lot going on inside this spider!

The black lines/marks on the top of the abdomen are the result of tissues moving apart under the skin. When they move closer together, the lines become fainter. There is very pale yellow stripe down the middle of the dorsal abdomen; barely noticable, as in the picture. The black stripe in the middle of the carapace splits to become two separate lines on either side of the midline, from the fovea on forward.

The abdomen is quite plump and round. Given the coloring, this spider looks like a miniature pearl when viewed without magnification. Any green coloration on the abdomen is a reflection from the leaf.

See variation in abdominal pattern for this species here: