Update!
A fellow on facebook (if you're also on SKF and seeing this, that'd be cool!) is breeding and selling an almost identical species of crab, Amarinus Laevis. THey grow to approx 22mm, so they're just a tad bigger than amarinus lacustris. He's breeding them in fresh water successfully and selling them really cheap. If anyone was keen to get some I can put you in touch ? I have set of 8 females and 2 males arriving this week so pics coming soon. Apparently they're completely shrimp safe and survive/breed in water conditions suited to both neos/tigers and crystals/TBs. They do, however, snack on tiny snails but ignore adult ones. The guy keeping them says this allows him to have adult ramshorns in the tank to do clean-up duty without them breeding like mad and taking over the place.
So, let's see how this goes!!
Museum Victoria has some great photos!
http://collections.museumvictoria.com.au/species/14241