Yes, we keep finding new mammals - 408 in the last 15 years, by one count. Make it 409 with a cute rodent from South America. Heteromys catopterius is a new member of a group called the spiny pocket mice. The Overlook Spiny Pocket Mouse hangs out above 700 meters on mountain slopes in northern Venezuela. There's a good discussion in the linked article about how species are differentiated on habitat and characteristics.