The subgenus Odatria, sometimes known as the dwarf monitor lizards, consists of small monitor lizards found in Australia and Indonesia. Species in this subgenus include the smallest monitor species in the world, the tiny 16 gram Dampier Peninsula monitor, but also includes some more medium sized species such as the 240 gram black-palmed rock monitor. Taxonomy Odatria was coined by John Edward Gray in 1838, albeit as a genus name. Odatria is the most species diverse subgenus of monitor lizards, with 22 different species. The subgenus also includes two species complexes represented by the spiny-tailed monitor and the Timor monitor. Alternatively, Vidal et al. 2012 splits Odatria into two species groups represented by the spiny-tailed monitor and the black-headed monitor. In the past, tree monitors such as the green tree monitor have sometimes been included within Odatria as well as Euprepriosaurus, but now form their own subgenus Hapturosaurus. A 2020 phylogenomic study by Brennan et al. found that Odatria is most closely related to much larger Australian monitor lizards from the subgenus Varanus, which includes the largest living lizard, the Komodo dragon, as well as the monotypic subgenus Papusaurus of which the crocodile monitor is the only member of. Together, Odatria, Varanus, and Papusaurus form a monophyletic clade of Indo-Australopapuan monitors. The same study found the black-palmed rock monitor, the largest species within Odatria, as sister to the rest of Odatria, making it the most basal species within the subgenus. Vidal et al. 2012 also recovers this species as the most basal, although within the V. tristis group. During the early-mid Oligocene, the genus Varanus dispersed in two directions. The southeastern dispersion into Indo-Australia likely occurred shortly after the collision of the Asian and Australian tectonic plates, which created a connection between Sahul and Sundaland, i.e., an Indonesian land bridge that would have facilitated the dispersal of monitor lizards into Australia. The existence of this land bridge also likely allowed the Indo-Australopapuan clade including many Odatria species to disperse back into Indonesia. Phylogeny Species Groups Vidal et al. 2012 separated Odatria into two species groups; the V. acanthurus group included V. acanthurus, V. baritji, V. brevicauda, V. bushi, V. caudolineatus, V. eremius, V. gilleni, V. kingorum, V. primordius, and V. storri, while the V. tristis group included V. auffenbergi, V. glauerti, V. glebopalma, V. mitchelli, V. pilbarensis, V. scalaris, V. semiremex, V. similis, V. timorensis, and V. tristis. To maintain