Julii vs trilineas cory

[starsman20]

6 months ago I bought 6 juliis. After about 2 months I could only count 5 just figured there was a death I couldn't find. One of the 5 died about 2 weeks ago so I thought there were 4 left. Today I decided to remove the last decoration that wasn't a plant, a big dragon. That opened up some room to spread out the dragon rock. As I did that I found the missing fish. It is half as big as the others. Now I wonder if this is a julii and the others are false or vice versa. Since this one does not school with the others should I move it to another tank? Its hiding in the rocks still. This was the best shot I could get. Other picture is of what the other 4 look like

[starsman20]

Or could this be a corydoras ambiacus????

[JettsPapa]

I can't get a good look at the one in the first picture, but I'd say it's very likely that they're all trilineatus.  True julliis are rarely offered for sale.

[starsman20]

 Ill try to get a better picture but it is for sure not the same. Its about the size of my neon tetras.  Much much smaller than the other corys.   Im thinking it might be a pygmy of some sort. Not more than 1.25 in. The others are 2+  

[starsman20]

My real question is should I leave it with the group or move it to a different tank? And how do I figure out how to get more so he's not alone?

[Joshua14]

Definitely trilineatus in the bottom picture. If I was a gambler I'd say the other one is as well. Even if it's not, I'd leave it in there.