''Tropicagama'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of large-bodied lizards in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Agamidae. The genus is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

, with only one species listed: ''Tropicagama temporalis'', commonly known as the swamplands lashtail or northern water dragon. This semi-arboreal species inhabits the tropical savannah woodlands of northern Australia, as well as parts of

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

and southeastern

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

Taxonomy

From its original description in 1867 until 2017, genus ''Tropicagama'' has previously been included in multiple other genera, including ''Amphibolurus'', ''Gemmatophora'', ''Gowidon'', ''Grammatophora'', ''Lophognathus'', and ''Physignathus''. The new genus — ''Tropicagama'' — was created by Melville et al in 2018, after an extensive analysis of three genera (''

Amphibolurus ''Amphibolurus'' is a genus of lizards in the family Agamidae. The genus is endemic to Australia. Description Characteristics of the genus ''Amphibolurus'' include: * Moderate size nout–vent length * Long limbs and long tail * One to five ...

'', ''

Gowidon ''Gowidon'' is a genus of arboreal lizards in the family Agamidae. It is monotypic with a single recognised species, ''Gowidon longirostris'', commonly known as the long-snouted lashtail or long-nosed water dragon. It is found in Northern Terri ...

'' and ''

Lophognathus ''Lophognathus'' is a genus of large-bodied agamid lizards, consisting of two species — ''L. gilberti'' and ''L. horneri'' — both of which are endemic to northern Australia. Along with several other closely related genera (e.g., ''Amphibolur ...

'') that have had long-standing inconsistencies in their taxonomic classification. The morphological and mitochondrial DNA analysis revealed that four distinct evolutionary lines were lumped in the former genus ''

''. As a result, the former genus ''Lophognathus'' has now been split into genera ''

'', ''

'', and ''Tropicagama''. All of these genera are contained within subfamily

Amphibolurinae The Amphibolurinae are a subfamily of lizards in the family Agamidae. Members of this subfamily are found in Australia and New Guinea, although one species, the Chinese water dragon, is found in Southeast Asia. Genera Genera within the subfamily ...

Phylogeny and biogeography

Sequencing and analysis of mitochondrial DNA, along with

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

and divergence time analyses, reveals that the genus ''Tropicagama'' originated in the late

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

and early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Ma). It then migrated from New Guinea across Lydekker's Line into

Wallacea Wallacea is a biogeographical designation for a group of mainly Indonesian islands separated by deep-water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as ...

less than 1 Ma, during the mid-

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

epoch. Wallacea is a zone of mixing between

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is ''funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''Biota (ecology ...

of the

Indomalayan The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia. Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indi ...

and Australasian

ecozones An Ecozone may refer to: * Ecozone (Canada), one of 15 first-level ecological land classifications in Canada * Biogeographic realm, the broadest biogeographic division of Earth's land surface (referred to as ''ecozone'' by BBC) * Biome, a large c ...

. The eastern border of this zone is represented by a zoogeographical boundary known as Lydekker's Line, while the

Wallace Line The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographical realms of Asia and Wallacea, a trans ...

defines the western border.

Description

''T. temporalis'' is a slender agamid lizard of moderate size, with long limbs and a long and slender tail. The head is narrow and moderately elongated, with a short rounded snout and a prominent canthal ridge and tympanum. A broad white stripe extends from the tip of the snout, over the lower and upper lips, continuing below the tympanum and down the lateral portion of the body. This stripe tapers off at the hind legs, and it is intersected by three dark bands at the neck, shoulders, and upper back. The portions of the head above and below this stripe are a uniform dark gray or brown color. There is a prominent dorsal crest of enlarged

keeled scales Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, Campbell, J. A., Lamar, W. W. (2004). ''The Venomous Reptiles of the Western Hemisphere''. Itha ...

extending from the occiput to the shoulder. This crest continues as a ridge from the shoulder along the spine to the base of the tail. The front legs are darker in color and have more strongly keeled scales than the hind legs. A second, shorter white stripe sometimes extends from the posterior mandible to the area of the temporomandibular joint. The snout-to-vent length is ; hindlimb length is .

Distribution and habitat

''T. temporalis'' is mainly found in the far northern Australian coastal regions in the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

and the western portion of the

Cape York Peninsula Cape York Peninsula is a large peninsula located in Far North Queensland, Australia. It is the largest unspoiled wilderness in northern Australia.Mittermeier, R.E. et al. (2002). Wilderness: Earth’s last wild places. Mexico City: Agrupació ...

. It also occurs in the southern part of New Guinea and on some of the islands to the north of Australia, as far north as the

Maluku Islands The Maluku Islands (; Indonesian: ''Kepulauan Maluku'') or the Moluccas () are an archipelago in the east of Indonesia. Tectonically they are located on the Halmahera Plate within the Molucca Sea Collision Zone. Geographically they are located ...

of Indonesia. Within its distribution, this semi-arboreal species can be found in a range of habitats, including

coastal dunes A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

, tropical savannah woodlands, monsoon forests, paperbark swamps and

billabong Billabong ( ) is an Australian term for an oxbow lake, an isolated pond left behind after a river changes course. Billabongs are usually formed when the path of a creek or river changes, leaving the former branch with a dead end. As a result ...

s, creeks and riverine environments. In particular, it can be found in the

Arnhem Land tropical savanna The Arnhem Land tropical savanna is a tropical and subtropical grasslands, savannas, and shrublands ecoregion in Australia's Northern Territory. Geography The ecoregion occupies the peninsula of Arnhem Land and its offshore islands, includin ...

, the

Cape York Peninsula tropical savanna The Cape York Peninsula tropical savanna is a tropical grasslands, savannas, and shrublands ecoregion in northern Australia. It occupies the Cape York Peninsula in Queensland, mainland Australia's northernmost point. It is coterminous with t ...

, the

Carpentaria tropical savanna The Carpentaria tropical savanna is a tropical and subtropical grasslands, savannas, and shrublands ecoregion in northern Australia. Geography The ecoregion lies in northwestern Queensland and northeastern Northern Territory, south of the ...

, the

Trans-Fly savanna and grasslands The Trans Fly savanna and grasslands are a lowland ecoregion on the south coast of the island of New Guinea in both the Indonesian and Papua New Guinean sides of the island. With their monsoon and dry season climate these grasslands are quite di ...

, the Victoria Plains tropical savanna, and possibly the

Kimberley tropical savanna The Kimberley tropical savanna is a tropical and subtropical grasslands, savannas, and shrublands ecoregion in northwestern Australia, covering portions of Western Australia and the Northern Territory south of the Timor Sea. Geography The ec ...

Gallery

References

{{Taxonbar, from1=Q77115899, from2=Q3259313 Agamid lizards of Australia Agamidae Monotypic lizard genera Agamid lizards of New Guinea Reptiles of Oceania Reptiles of Queensland Taxa named by Jane Melville Taxa named by Stephanie N.J. Chapple