I spent a crazy amount of time trying to get a shard to drop. I had had 10+ shoulderpads , luclin shards and everything else that was supposed to be uncommon or rare. 100s of Rockhoppers and Lightcrawlers died.
Then it occurred to me that this is a level 35 quest and all of the Lightcrawlers and small/regular Zelniaks are < Level 32. Hoppers are all 40+
As soon as I concentrated on Wolves (L32-L34) and Large Zelniaks (L32-L35) I had it drop. Not once, but seven times.