The one without red coloration is probably another species, Microtomus luctuosus. They look nearly identical to purcis but lack the red coloration on their femur. Interestingly they seem to be able to hybridize together cause a friend of mine found several specimens in his area that looked like a mix between purcis and luctuosus, and he finds both species in that area.
I keep my adults communally with a piece of egg flat. They aren't entirely communal but adults get along fine with each other as long as they are well fed