New data on the rare Varanus bogerti Mertens, 1950 and V. telenesetes Sprackland, 1991 (Squamata: Varanidae), two endemic monitor lizard taxa from island groups off southeastern New Guinea

Some monitor lizards are among the least studied of all vertebrate species, being known only from a handful of old voucher specimens in museum collections. This includes tree monitors related to Varanus prasinus (Schlegel, 1839), namely V. telenesetes and the melanistic V. bogerti, which inhabit the Trobriand, D'Entrecasteaux and Louisiade islands off southeastern New Guinea. We provide new data about morphological variation and natural history for V. bogerti supplemented by a detailed description of the colour pattern in hatchlings. The exact distribution range of V. bogerti is still insufficiently known, and a historical record from the Trobriand Islands needs verification. We also discuss the taxonomic status, distribution and origin of the holotype of V. telenesetes, the only known specimen of this taxon, in relation to V. bogerti and V. prasinus. The examination of specimens of V. prasinus from southeastern New Guinea allows a discussion about the putative sympatric occurrence of, and past gene flow between multiple tree monitor species on the D'Entrecasteaux islands in light of climate-induced sea level changes during the Pleistocene. Only further field work and future investigations will yield sufficient answers to the open questions surrounding these rare New Guinean tree monitors.