Comparing to the examples
here, yours looks quite similar to the 2.5mm JST PA, but there are at least a couple differences visible. Note how the 2mm version of the genuine JST header doesn't have slots in the top, while the header in your picture does. Nor do either of the genuine connectors have a groove on the bottom of the header, while yours does. This being the case, I'd guess that what you have is a clone of a PA, but it might be close enough to be physically compatible with a genuine JST PA. (Of course, it's also possible that JST just changed their molds at some point.)