Primates in Peril

Philippine Tarsier
Carlito syrichta (Linnaeus, 1758)
Philippines
(2014)
Myron Shekelle, Sharon Gursky & Stefan Merker
The Philippine tarsier (Carlito syrichta) is a collection
of at least three evolutionary significant units (ESUs),
which do not perfectly conform to the three debatable
subspecies, creating a very uncertain taxonomic
situation in which some populations almost certainly
face an imminent threat of extinction. Furthermore,
we don’t know which one, or ones, those are, and with
deforestation having removed nearly all of the Philippine
tarsier’s original habitat in many places, there is urgent
need to act now and identify the conservation priorities
of this unique primate.
The history of the Philippine tarsier’s IUCN threat status
has been disturbingly unstable, indicating a profound
lack of knowledge. Originally listed as Endangered (E),
it was downgraded in 1996 to Lower Risk/conservation
dependent (LR/cd). Subsequently it was listed as Data
Deficient (DD), and is currently Near Threatened
(NT) (Shekelle & Arboleda 2008). What this reflects
is that the metapopulation of all tarsiers found within
the Philippines, scattered over 4 large islands (Samar,
Leyte, Bohol, and Mindanao) and an unknown quantity
of smaller islands (e.g. Dinagat, Basilan, etc.) is not in
imminent danger of going extinct across its entire range,
but this merely masks the greater conservation problem
that some populations almost surely have.
Philippine Tarsiers
(Carlito syrichta subspecies)
(Illustrations: Stephen D. Nash)
Modern genetic tools reveal that Philippine tarsiers,
Carlito syrichta, are a group of at least three evolutionary
significant units (ESUs) (Brown et al. 2014). Perhaps
coincidentally, three subspecies have been described: T.
syrichta syrichta from Leyte and Samar, T. s. carbonarius
from Mindanao, and T. s. fraterculus from Bohol. Few
taxonomists have accepted the distinctiveness of these
subspecies, but Brandon-Jones et al. (2004) inferred
that lack of acceptance might have had as much or
more to do with the absence of evidence as it did with
the absence of evidence for taxonomic separation.
The distribution of the known ESUs is similar, but not
identical to the distributions of the subspecies. As
with many taxonomically cryptic nocturnal species,
morphological variation is minimal. This is further
complicated by museum specimens of Philippine tarsiers
being greatly skewed toward just two sites on the Gulf of
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