below). Second, many mammalian species (as well as
other animals) are declining for various reasons. The
conservation status of mammals as well as other animals
is evaluated by two organizations, the International
Union for the Conservation of Nature (IUCN) and
the Convention on International Trade in Endangered
Species (CITES). These organizations will be cited
throughout this chapter as I discuss recent changes
in taxonomy as well as the apparent declines of some
species.
The order Chiroptera, the bats (plate 16- 2), is second
only to rodents (order Rodentia) in mammalian
Neotropical species richness. Nearly 40% of
Neotropical rain forest mammal species are bats, and
236 species occur in the Neotropics. An account of bats
and their remarkable adaptive radiation is described
and illustrated in chapter 8, and thus bats are not
discussed here.
The Simians of the Rain Forest: New World
Monkeys
Neotropical monkeys all belong to a group named the
platyrrhines, a word that refers to the position of the
nostrils. New World monkeys’ nostrils open at the
sides (plate 16- 3). This is in contrast with Old World
monkeys, the catarrhines, whose nostrils are more
closely spaced and point downward (humans, having
evolved from apes in Africa, have a similar nostril
position). Some New World monkeys are known less
for their nostrils, however, than for their tails. Some
common and widely distributed platyrrhines, such
as the capuchins, spider monkeys, woolly monkeys,
and howler monkeys, have prehensile tails, which they
skillfully use as a one- fingered fifth limb (chapter 8).
When the previous edition of this book was published
in 1998, authoritative accounts listed approximately 60
species of New World Monkeys, but the number of
New World monkey species is now considered to be
- The upward spike has come about mostly because
of a strong recent trend in splitting, mostly by elevating
subspecies to species level. In 2011 an expedition in
Brazil discovered a new monkey species, which has
been named Milton’s Titi Monkey (Callicebus miltoni),
after Milton Thiago de Mello, a famous Brazilian
primatologist. Yet another new species, the Urubamba
Brown Titi Monkey (C. urubambensis), was described
in 2015 from a remote area along the Urubamba
River in Peru. This newly described titi monkey is a
taxonomic split from the Brazilian Brown Titi Monkey
(C. brunneus). It may seem amazing that a group as well
known as the primates is still presenting us with new
species. However, Amazonian primate diversity has
historically presented taxonomic problems; recently,
more study combined with new information about
the genetics and ecology of Neotropical monkeys has
clarified the status of various previously problematic
examples. Nonetheless New World monkeys remain
a taxonomic work in progress and more changes in
classification are likely.
Even as more is learned about the classification of
New World monkeys, more species are considered
threatened or endangered. The IUCN currently lists
58 monkey species as threatened and 33 as endangered
(of which 12 are considered critically endangered).
The reason for loss of primates has to do with extensive
forest clearance and fragmentation as well as local
hunting pressure (chapter 18).
Platyrrhines have not only extensively speciated but
also adaptively radiated to occupy many ecological
niches in various kinds of Neotropical forest. There
are large apelike monkeys (spider, woolly, and howler
monkeys), medium- size “typical” monkeys (capuchins
and squirrel monkeys), monkeys with bald faces
(uakaris), monkeys with long, shaggy fur (sakis),
nocturnal monkeys (night monkeys or douroucoulis),
small, lemur- like monkeys (marmosets), and squirrel-
like monkeys (tamarins).
New World monkeys are forest animals, avoiding
savannas. There are no Neotropical equivalents of the
mostly terrestrial baboons that roam the African plains.Plate 16- 3. Note how the nostrils open to the sides of the nose
on this Mantled Howler Monkey (Alouatta palliata). That is
typical of the platyrrhines, or New World monkeys. Photo by
John Kricher.320 chapter 16 from monkeys to tarantulas: endless eccentricities