Mystery stingray/skate from Thailand

Saw this on the Boonsung wreck near Kao Lak in the Andaman Sea a few years ago. I've never been able to pinpoint what it is. For a long time I thought it was a skate (e.g. Raja sp.), but now I think it looks more like some of the freshwater Himantura sp. found in Thailand. But obviously this is salt water. Would appreciate any insight!

[youtubehd]UtccqUfeqTQ[/youtubehd]

So, new species then!

Anyone know a ray/elasmobranch specialist?

I've been digging further and it appears to fit Himantura imbricata ("scaly whipray" , formerly Himantura imbricatus) very well. Apparently they like estuarine habitats, and migrate between saltwater and freshwater, which fits well because the Boonsung wreck is not too far from a couple of estuaries.

Apologies for the one-man thread.

I've now been told by an elasmobranch expert that this is Himantura walga.