Possibly melanistic T. dobrogicus larva; oppinions?

This little guy is a bit of an anomaly. It hatched in Dec 2011, its siblings all morphed about 4 weeks ago. It has grown much more slowly than all the other dobro larva and is about 3" now. It has always been darker, more of a grey with black spots rather than the typical mottled brown/tan even when small. It also lacks the usual light pigment in the eyes and has no belly color despite being fed daphnia and cyclops for the first 4 months.Its not as aggressive as its siblings but eagerly snaps up earthworms and blackworms. It has darkened significantly in the last month and has probably doubled in size. The pictures are not super clear but the shot with one of the normal larva really shows the contrast. What does everyone think? I am really curious to see what it looks like after it morphs and continues to develop.