Begonia handelii var. prostrata

A native of Southern China and Indo-China, this Begonia can grow to over a foot tall, with leaves staying around 4-5″.  It is very easy to keep small in the terrarium however, and seems to be a slower growing, albeit not too difficult, species.  The stems are a striking red and the white spotting on foliage becomes even more prominent as the plant matures.

drawing from efloras.org