Primates in Peril

Northern Brown Howler
Alouatta guariba guariba (Humboldt, 1812)
Brazil
(2012, 2014)
Leonardo Gomes Neves, Leandro Jerusalinsky, Anthony Rylands, Fabiano R. Melo & Maurício Talebi
Male northern brown howler(Alouatta guariba guariba)
(Illustration: Stephen D. Nash)
The brown howler is separated into two subspecies,
the northern brown howler, Alouatta guariba guariba,
and southern brown howler, A. g. clamitans (Rylands
et al. 2000; Groves 2001, 2005). Following a study of
the morphology of the cranium and hyoid apparatus of
the two forms, Gregorin (2006) considered them to be
full species, using the name A. fusca (É. Geoffroy Saint-
Hilaire, 1812) rather than A. guariba (Humboldt, 1812)
for the northern form, following the recommendation
of Hershkovitz (1963). Rylands and Brandon-Jones
(1998) argued that the correct name is in fact guariba.
Kinzey (1982) concluded that A. g. guariba occurred
north of the Rio Doce; clamitans to the south. Rylands
et al. (1988) observed what they believed to be A. g.
clamitans further north, in the middle Jequitinhonha
valley, and indicated that the Rio Jequitinhonha basin,
not the Rio Doce, divided the two howlers. The extreme
rarity of brown howlers north of the Jequitinhonha
has confounded attempts to clarify the taxonomy.
Only recently have few and minuscule populations
been located in southern Bahia (Neves et al. 2015; L.
G. Neves, unpublished data). Gregorin (2006) argued
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that the original range of the northern brown howler in
fact extended from Bahia (Rio Paraguaçú) south along
the coastal forest to the state of Rio de Janeiro (crossing
as such the lower and middle Rio Doce), and that
clamitans, the southern form, occurs inland north as
far as the upper and middle Jequitinhonha. This would
be compatible with the findings of Rylands et al. (1988)
in the Jequitinhonha valley and, in this case, some of
the populations surveyed by Chiarello (1999) may have
been of the northern subspecies A. g. guariba. Here, we
maintain the names and subspecific classification as
used by Rylands et al. (2000), Groves (2001, 2005), and
Glander (2013).
Both sexes of A. g. guariba are a red-fawn colour, the
females being rather duller in colour. Alouatta g. guariba
inhabits lowland, submontane and montane Brazilian
Atlantic forest. It is a folivore-frugivore, including more
fruit in its diet according to seasonal availability (Neville
et al. 1988; Mendes 1989; Chiarello 1994; Glander 2013;
Rylands and Mittermeier 2013). As such, brown howler
monkeys are important seed dispersers for several plant