Found this 4th instar Podisus nymph in some sort of pine or juniper. It took a good month, but I finally got it to adulthood. With the dorsum of the abdomen entirely black, red, and white (or something close to white), but certainly without yellow-orange or creamy white patches, Evans key would point to this being serieventris. I think when I tried this out when I was younger, the wording for the colors threw me off. I would call the entire dorsum creamy white as opposed to true white (think P. placidus).

I keyed the adult out to serieventris.