Islands Between the Realms: A Revised Checklist of the ...

108 André KOCH et al.: A Revised Checklist of the Herpetofauna of the Talaud Archipelago, Indonesia
1. INTRODUCTION
The Talaud Archipelago represents the northern most area
within the Wallacea transition zone between the Oriental
and Australian faunal regions. The remote island group lies
in the northern Molucca Sea between North Sulawesi,
Mindanao in the southern Philippines, and Halmahera in
the northern Moluccas. The Talaud Archipelago comprises
three main islands: Karakelong, Salibabu and Kaburuang
(Fig. 1). Geologically, the Molucca Sea Plate with its
inverted U-shape dips east under Halmahera and west under
the Sangihe Arc (MCCAFFREY et al. 1980). The Talaud
Islands are situated on the Sangihe forearc separated by
a deep ocean trench from the largely submarine Sangihe
Arc with its few emergent volcanic islands like Sangihe
and Siau (HALL 2002). The Talaud Island group consists
of a sedimentary sequence of Middle Miocene to Pleistocene
age and includes probable mid-Miocene volcanic
rocks and volcaniclustic turbidites (MOORE et al. 1981).
Pleistocene coral limestone, the youngest rocks on Talaud,
are exposed mostly along the coast lines (Fig. 2), but also
at 400–500 m elevation on Kaburuang, showing the significant
amount of recent uplift (MOORE et al. 1981). The
highest elevation of only 650 m above sea level is found
on Karakelong Island.
The Talaud Islands together with Sulawesi and other islands
of present day central Indonesia belong to a biogeographic
transition region called Wallacea (see summaries
by MAYR [1944] and SIMPSON [1977]). Australopapuan and
Asian animals meet at the respective outer limits of their
distribution. Consequently, in the light of biogeography,
the Talaud Islands form the northernmost submerged area
of this region. Traditionally, the Talaud Archipelago has
been dealt with scientifically with Sulawesi to which it is
indirectly connected via the Sangihe Island arch. However,
the direct over-water distance to North Sulawesi of
about 300 km is significantly more distant than Halmahera
in the Moluccas (ca. 210 km) or Mindanao in the
Philippines (ca. 170 km).
Fig. 1.
Map of the Talaud Islands located between Sulawesi, Halmahera (Moluccas) and Mindanao (Philippines).