This spider surprised me by having an epigynum that is a very clear match for Mecaphesa celer, per figure 471 in Dondale & Redner 1978. I assumed it was M. dubia.

I found the spider on a yellow Slender-Stem Bitterweed flower on March 13. It made egg sac in captivity on March 22. The egg sac hatched on April 9. I released all of the hatchlings because I thought they were dubia and I don't need any more dubia. I now wish I had raised them to doubly confirm what the epigynum indicates.

The abdominal pattern is similar to M. dubia. So far I have only confirmed M. dubia for red that covered the entire abdomen, so this pattern could still be unique to M. celer. Also, I can clearly see on this specimen that it has the special arrangement of four dark spots on the anterior dorsal abdomen that I have seen in every single M. celer male so far. That could also be a good indicator. However, I also have confirmed M. celer female that are entirely yellow, such as this one:



This complicates our ability to identify M. dubia, as we now have to distinguish red dorsal patterns. Looks like I'll need to collect more M. dubia females after all. I am finding several classes of celer-like males that are not likely to all be M. celer, so it's still possible that the present specimen belongs to one of those other classes. But because the dorsal epigynum is a spitting image of the figure in Dondale & Redner 1978, I'm calling this M. celer for now.

In particular, notice how different the present epigynum is from the following M. dubia: