It looks like what they are calling Cryptocoryne x willisii. This name covers a number of hybrids between C. parva and other Sri Lankan crypts, such as C. beckettii, or C. walkeri. C. x willisii plants used to be called either C. nevillii or C. lucens, with the former having rather short, triangular leaves and the latter having longer leaves with some waviness along the edges. There appear to be more varieties of C. x willisii than the old nevillii and the old lucens. They differ in how much brown they develop on their leaves and how the brown color is distributed. For example, I have a variety of C. x willisii that differs from yours in that the brown color develops along the edges of the leaves, leaving the center green. In your plant, the brown seems to be more evenly distributed.
My experience with C. x willisii has been that it transplants well and never melts.
This is the old nevillii:
This is the old lucens:
My experience with C. x willisii has been that it transplants well and never melts.
This is the old nevillii:
This is the old lucens: