a lion's first nature is to go after fish and inverts that fit in its mouth. after all, shrimp do make a good portion of a lion's diet. While i know a mantis isn't a shrimp technically, i would worry about a small mantis out on a food foraging expedition. remember, just because you might only ever see the mantis hiding from you, it doesnt mean it hides all the time. especially such an active species as N. wennerae.
edit: and one more thing, a lion's hunting behaviour is an amazing ritual to watch. dont miss out on it if you ever get the chance to see it. The lion will spread its "wings" out wide to corner and corral the prey into a corner. the huge fins distract the prey and some dwarf lion species actually shake their fins to confuse the prey further. the reason i bring this up is that during a hunt, a lions behaviour is designed to confuse the prey (a mantis in our case) so that it kind of forgets the fact that it's even being hunted.
