All of my wild notatus are relatively small compared to other severums, but the male is still larger than all of my females. They're very easy to tell apart, though. Males will have the incredible black/maroon spotting all throughout (see my avatar) while the females seem to lack this almost completely in the head/gill region.
My male topped out around 8" or so while my other male severums made it to like 10". My female notatus are only 5 - 6".