Friday, October 7, 2011

Varanus Salvator Ziegleri From Moluccas Indonesian Species

The Southeast Asian water monitor lizard Varanus salvator ziegleri (Laurenti, 1768) is among the largest extant squamate reptiles of the world. It is also the most widespread 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). However, taxonomy and intraspecific diversity of this giant Asian monitor lizard species complex have long been neglected. Anew era started in 2007, when the three traditionally recognized subspecies from the Philippine Archipelago were elevated to full species status due to significant morphological differences (Koch et al., 2007a). In another recent study, the Philippine species were reinvestigated morphologically and it could be shown that this vast archipelago harbors no less than five different species of the closely related V. salvator complex (Kochet al., 2010).

Varanus salvator ziegleri
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 (Batjan) 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, 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 Varanus salvator ziegleri from the Moluccas. Brandenburg (1983) adopted these earlier records from Halmahera and Obi. More recent authors, however, largely ignored the possible occurrence of water monitor lizards in the Moluccas (see, e.g., Eidenmüller, 2009).

Recently, however, populations of Varanus salvator ziegleri were encountered on several Moluccan islands such as those of the Sula Archipelago and Obi (Weijola and Sweet, 2010). Subsequent investigations of the varanid collection at the Senckenberg Museum, Frankfurt (SMF), revealed one juvenile specimen of Varanus salvator ziegleri from the island of Obi, which was donated by the Museum Zoologicum Bogoriense on Java, Indonesia, in 1957. This voucher specimen formed the base for Mertens’ (1959) novel island record for Obi. The specimen exactly matches in coloration and pattern with a live specimen from Obi as depicted by Weijola (2010). Due to unique characteristics in the color pattern of the Obi population, we here describe a new subspecies of the Southeast Asian water monitor lizard Varanus salvator ziegleri.

Field work on Sulawesi and adjacent islands was conducted between 2005 and 2007. In addition, voucher
specimens of major European and Indonesian natural history museums were studied. Museum collection acronyms used follow Leviton et al. (1985). Examination methods of standard morphometric and meristic characters used in this study are based on the works of Mertens (1942), which were later further developed and expanded by Brandenburg (1983) and Böhme et al. (1994). For each voucher specimen examined
21 external morphometric and meristic characters were recorded. In order to minimize the errors based on
observer bias, all measurements and scale counts weremade by the senior author. In addition, four proportion
indices were calculated.

Head measurements were taken with a slide-caliper to the nearest 1 mm. Body and tail lengths of subadult and adult specimens were taken with a measuring tape. Scale counts were recorded using pins and with check marks. A binocular microscope or a magnifying-glass was used for juvenile specimens with very small scales. For the measurement of the scalation character Q, the first continuously tail-spanning row of scales near the tail base was counted by excluding the first rows immediately after the cloaca, which form a non-continuous bow.

The transverse scale rows on the ventral side to the insertion of the hind limbs (character T) were counted up to the last continuous row when the scales eventually decrease and are of irregular shape. In contrast to Brandenburg (1983) and Böhme et al. (1994), “N” instead of “n” abbreviates the number of gular scales from the tip of the snout to the gular fold, to avoid confusion with the standardized variable “n” for the number of voucher specimens examined.


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