No way to confirm this unknown star as the photo does not give much to go on.
It could be the Spanish Order of Military Merit in Red, given what is represented on his ribbon bar, but the ribbon bar does not confirm the grade of award. Given this though, it is probably a more plausible theory than a higher grade of the Naval Merit Order which is not impossible but less likely.
Another alternative is a foreign order unaccounted for/unknown thus far. For example, if it weren't for this photo above we would not know he was awarded the Croatian Order of King Zvonimir. It's not represented on his ribbon bar.