What you have now is a clear statistical evidence that shows most of your audience is female, and that you should take special care about that evidence.
Statistical evidence also shows that AT LEAST 20% of your audience is male. That is a really big number. Just imagine telling your SEO or stock holders "oh, it's just 20% so we have no problem in giving that away".
More important: you don't provide any info on your service, but it obviously caters a female audience. Then... why do you have such important amount of males? There's something there. And in the few cases I have seen this happen, it ended in a very interesting opportunity.
Basically, it seems you have something that is a bit diffuse somehow, and with a few adjustments, it can become something else. Probably more users, or more sales from that existing group or whatever (again, I have no idea what your service is about, but you get the concept)
In short: not only you need male personas, but they're of utmost importance