http://www.wrftpb.com/psiv/htm/ps4-enemy10.htm
The Profound Darkness does give an EXP meseta reward.
The first two forms give 5 EXP, so in a party of 5, that's 1 EXP for everyone... and of course, only 1 meseta...
The third (and final) form, gives 9999 EXP, so in a party of 5, that's about 1999, and strangely, 2 meseta, rather than the typical 1 meseta by this point.
That's definitely odd. Especially how random the EXP reward for the final form is!