M. itinerans var. gigantea was just a preliminary name, it was never published. var. xishuangbannaensis is also an unpublished name, but will be official by March 2008. "ensis" means from, so when you see a name like that and take out the "ensis", you will easily find out where it is from. Xishuangbanna is a region of southern Yunnan province, Dechang appears to perhaps be another region of Yunnan (according to the description of "M. dechangensis", but Google maps shows some sort of Dechang further north), but in any case, they are not related.
Here are pictures
http://natureproducts.net/Forest_Pro...rans_tall.html