If there's brown or yellow on the head I would maybe lean more towards Russo. Or If you can actually make out an eye stripe on her. That is of course unless she's actually a super mojave and has the headstamp and eyestripe.
Honestly the only way to be sure is by breeding her out.
In general my experience with the BEL combos are:
Lesser mojaves are very clean, almost white. It can be very hard to make out an eyestripe. Sometimes they'll get a yellow stripe on the back or have a slightly yellow tint when they get older
Lesser Russos can still be very white, but they have a higher chance of getting a slightly larger stripe down the back and the eyestripes are more visible. The stripe seems to be more dusty colored not as yellow as the Lesser mojave. Also may be prone to the bug eyes like a super lesser.
Super mojaves do tend to have more color around the head.
Honestly your best chance would be to breed her to something not in the BEL complex so you have a clear idea on what she is. For example...
The first four are from one clutch, can you tell the lesser special from the lesser mojave?
The second are my three current hatchlings. Super mojave, coral glow super mojave and a coral glow mojave special. Which one is which?
Otherwise, I've never seen a mojave russo under a blacklight... but it might help.
