How many species of these small South American deer are truly distinct is a question that is not fully settled yet. In common with the scientific fashions of the time, a great many species were named in the 19th century, only to be merged in the 20th and then split apart again in the 21st (not always along the same lines, of course). As a result, many of the species we recognise today weren't considered such until recently and have not been individually studied to any great extent beyond demonstrating that they exist. On the other hand, the reason that we confused them for so long - and still aren't entirely sure how many they are - is that they are all quite similar. This is especially true of the various kinds of brocket, all of which are currently placed in the genus Mazama.