The black rat (Rattus rattus) is a common long-tailed rodent of the genus Rattus (rats) in the subfamily Murinae (murine rodents). The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.
Identification quiz to test your ability to distinguish black/brown rats: http://www.ratbehavior.org/QuizNorwayRatRoofRat.htm
Differences between the species in NZ: https://www.stat.auckland.ac.nz/~smiller/rat_id
Example pictures of the different species in NZ: https://www.stat.auckland.ac.nz/~smiller/ratPics