Porcellio expansus has been the most sought after species for a while. They grow very large for a terrestrial isopod (many times the biggest most people see in their back yards) and older males have extremely long uropods. There are two different forms, one where the "skirt" (margin of the pronotum) is light orange and one where the skirt is yellow. Porcellio succinctus looks similar but the skirt is white.
