You are doing yourself a disservice here. Actually, all known Potanthus species from the peninsular part of Thailand are also found in Malaysia, and they are the same subspecies.
If you could look at my photos again, I would be very grateful, as I am nearing publication of a paper listing the species from Koh Samui Island, and would like to be certain of my facts.(I do not want to put down Potanthus sp.1, Potanthus sp.2, etc). Thanks.