Here we go...
Dianema urostriata is the Flagtail Porthole Cat.
D. longibarbis is the Porthole Cat.
There's also Hoplosternum littorale and H. punctatum, the Armoured Cat (Lepthoplosternum pectorale), the Hoplo (Megalechis personata), and the Tail Bar Hoplo (M. thoracata). I haven't seen many of these at the chain LFS, but they're cheap at some of the independent ones and seem to be good community residence. Some get a little large, but the Hoplo group (this paragraph) is legendary for tolerance to less-than-perfect water quality.