Dr. Darren Naish has published in his terrific blog, Tetrapod Zoology, a four-part article on the astounding series of mammal discoveries made by Dr. Marc van Roosmalen in the Amazon region.
While van Roosmalen is well known as a conservationist and for describing new species of monkeys, his work goes far beyond that. He has, for example, described the largest new mammal to be found since the early 1990s, the Giant peccary Pecari maximus. Awaiting description are a dwarf manatee, a possible new dolphin, another peccary, a tapir, and new species of deer and monkeys (many more monkeys). Most intriguing of all is the black and white jaguar (not a melanistic example of the common jaguar, but a distinct species which Bill Rebsamen so stunningly illustrated for my recent book Shadows of Existence: Discoveries and Speculations in Zoology (on which I corresponded with van Roosmalen during the research phase.)
It's possible, even likely, that some of the many specimens von Roosmalen has or is tracking down will prove to be something less than full species. He has, however, made a gigantic and underappreciated contribution to zoology. He has demonstrated that, as Bernard Heuvelmans, the founder of cryptozoology, once wrote, "The great days of zoology are not done."
Van Roosmalen's new website is a "must see"