HEADING EAST: A NEW SUBSPECIES OF Varanus salvator FROM OBI ISLAND, MALUKU PROVINCE, INDONESIA, WITH A DISCUSSION ABOUT THE EASTERNMOST NATURAL OCCURRENCE OF SOUTHEAST ASIAN WATER MONITOR LIZARDS André Koch 1 and Wolfgang Böhme 1 Submitted October 20, 2010. The Varanus salvator population from the Central Indonesian island of Obi, Maluku Province, is described as a new subspecies representing the most easterly confirmed occurrence of the widespread Southeast Asian water monitor lizard. The new taxon differs from the four recognized subspecies by unique characters of coloration and pattern such as a distinct dorsal pattern on the head in combination with reduced transverse rows on the anterior back which stand in contrast to the distinct and black-bordered, large light spots on the hind part of the body. In addition, the eastern border of the distribution range of the V. salvator complex is critically discussed in the light of historical voucher specimens from the Moluccas, New Guinea and even Australia. The Obi island record which had long been published but has never since been scrutinized, confirms the recently observed sympatric occurrence of members of the V. salvator and V. indicus species groups on several islands of the Moluccas. Fur- ther field investigations are needed to understand the different niche occupation between both these ecologically similar monitor lizard groups. Once more, our findings demonstrate the importance of the Central Indonesian is- lands of Wallacea as a global hotspot of varanid diversity and endemism. Keywords: Wallacea; Moluccas; Reptilia; Squamata; Varanidae; Varanus salvator ziegleri ssp. nov.; conserva- tion; systematics; biogeography. INTRODUCTION The Southeast Asian water monitor lizard Varanus salvator (Laurenti, 1768) is among the largest extant squamate reptiles of the world. It is also the most wide- spread member of the genus Varanus (Böhme, 2003), ranging from Sri Lanka in the west through continental Southeast Asia, the Greater and Lesser Sunda Islands to Sulawesi and the Moluccas (Koch et al., 2007a). How- ever, taxonomy and intraspecific diversity of this giant Asian monitor lizard species complex have long been neglected. A new era started in 2007, when the three tra- ditionally recognized subspecies from the Philippine Ar- chipelago were elevated to full species status due to sig- nificant morphological differences (Koch et al., 2007a). In another recent study, the Philippine species were re- investigated morphologically and it could be shown that this vast archipelago harbors no less than five different species of the closely related V. salvator complex (Koch et al., 2010). Another unresolved issue is the exact limit of the distribution range of V. salvator and its occurrence on the islands east of Sulawesi (see Koch et al., 2007a). De Rooij (1915), for instance, examined historical voucher specimens from Halmahera but also listed Bacan (Ba- tjan) within the species range. Mertens (1930, 1942, 1959, 1963) reported V. s. salvator from the islands of Obi, Halmahera, and Bacan at the eastern boundary (Fig. 1), although no material from either of the latter two islands was available to him. Instead, he referred to earlier authors like Bleeker (1856, 1857, 1860a, 1860b), who had reported V. salvator from the Moluccas. Bran- denburg (1983) adopted these earlier records from Hal- mahera and Obi. More recent authors, however, largely ignored the possible occurrence of water monitor lizards in the Moluccas (see, e.g., Eidenmüller, 2009). In con- trast, other early sources even claimed that water moni- tor lizards had reached Northern Australia (e.g., Boulen- 1026-2296/2010/1704-0299 © 2010 Folium Publishing Company Russian Journal of Herpetology Vol. 17, No. 4, 2010, pp. 299 – 309 1 Zoologisches Forschungsmuseum Alexander Koenig & Leibniz In- stitute for Animal Biodiversity, Section of Herpetology, Adenauer- allee 160, D-53113 Bonn, Germany; E-mail: andrepascalkoch@web.de, w.boehme.zfmk@uni-bonn.de.