Male or female?

Darlingi doesn't follow the same rule as marshalli - while marshalli females get impressive horns while the males don't, iirc both male and female darlingi get similarly sized horns.

In those C darlingi i have had, the msles have smaller horns. Not much, but still

It could go either way with the horns for C. darlingi. C. marshalli is the one that has the difference in their horn sizes. @Vanisher Males have smaller horns because they mature at smaller sizes for C. darlingi. But if they were to be the same size as a female and be side by side, it would be much more challenging to sexually tell them apart.