Greetings, brethern,
if you are a little older and digged through most of the GW publications that where every up, you might have heared of some ShapeChanging kind named "Lacrymole".
Since "Mark of the Xenos" is already offically on sale as a PDF, I was able to get a look the index of this books as part of a "sample".
Besides Tau, Orks and Tyrnids (for whom I do not care) and some heretics and chaos related foes, the book feautures in the "Other Xenos" Section
Bruul Parasites (?)
Crotalid (yes, I have read you once in an WhiteDwarf)
Diablodon (sounds like a dinosaur...naaaaaaa)
Lacrymole (!)
Loxatl Mercenaries
Know, I pounder and bounce around and off the wholes if I shall or shall not by a $20 PDF just to get an assortment of five potentiall tasty Xenos (covered on 8 pages in total).
**** it...I so wished that WE would get the Lycromole one day...but since they are one of these "and special guest starring" xeno types I do not think that they will be re-printed in all three/four product lines (like certain daemons and/or the orks)