Amethystine Python (Simalia amethistina)

The Amethystine Python (*Simalia amethistina*, previously *Morelia amethistina*), aka Scrub Python, is an extremely large (typical length 6.6m, maximum length 8.5m) species of snake in the family Pythonidae. Amethystine Pythons are generally nocturnal and aboreal, although they can be seen sunning themselves during the day.

The Amethystine python is found in Indonesia (Maluku Islands, Timur Laut Islands, Banda, Kai Islands, Aru Islands, Misool, Salawati, most of Western New Guinea, many islands in Geelvink Bay, such as Biak, Numfor, Yapen, and Supiori), Papua New Guinea (including Umboi Island, Bismarck Archipelago, Trobriand Islands, the d'Entrecasteaux Islands to Rossel Island, Louisiade Archipelago), and Australia (on some islands in the Torres Strait, the northern Cape York Peninsula south including the Atherton Tableland, and the eastern foothills of the Great Dividing Range). It is the largest native snake species found in Australia and Papua New Guinea.

It has a large elongated head, bearing enlarged plate-like head shields. Scales bear a milky iridescent sheen which has given rise to common and scientific names. Juveniles are less glossy than adults, with a weaker pattern. Lips and ventral surfaces are cream to white. There are deep thermoreceptive  pits on six or seven of the posterior lower labials, and two large, deep thermoreceptive pits on the rostral scale.

There are several species of python in the genus Simalia that were previously considered to be subspecies.
- *Simalia amethistina* - **Amethystine Python**
 - Main colour is usually grey to green or brown, with dark markings. The belly is pale grey to greenish-grey.
- *Simalia kinghorni* - **Australian Scrub Python**
 - Ground colour is pale yellowish brown to brown, marked with numerous irregular angular dark brown to black bands, blotches and streaks. Those on anterior body may form elongate streaks, while those on lower flanks often coalesce into one or more broken stripes. All aspects of pattern become obscure on posterior body and tail. A dark streak extends from eye down to corner of mouth.
- *Simalia oenpelliensis* - **Oenpelli Python**
 - The dorsal colour pattern is dark olive-brown with darkened blotches. The belly is pale and dull, varying from cream to yellow. The Oenpelli python is able to change its skin colouration, which tends to be lighter at night and darker in the daytime. Occurs in a restricted range in the Northern Territory, in the sandstone outcrops of western Arnhem Land.
- *Simalia clastolepis* - **Mollucan Python** aka **Yellow Python**
 - Found in Indonesia, As hatchlings they have a red colouration, which turns from brown to yellow as they age. As adults, they will get black scales along their spine. They can also be patternless or striped.
- *Simalia nauta* - **Tanimbar Python**
 - Found in Indonesia. This snake is often olive to brown with yellow diamond patterning.
- *Simalia tracyae* - **Halmahera python**
 - Found only on the island of Halmahera in Indonesia. Typical length 2.5 - 4m. The Halmahera python is recognized by its distinct red irises, as compared to the typical brown or gold irises of other closely related species. Other facial features include its rounded snout, black tongue, and pale blueish grey oral mucosa. *Simalia tracyae* is also marked by two or three pairs of enlarged parietal scales on either side of its head.
 - The Halmahera python changes color over a short period of time; however, scientists are unable to determine what circumstances cause the color change. At the darker end of the color spectrum, *Simalia tracyae* could be medium brown, orangish-brown, or russet. These colors could change to be a greenish-straw, grey-tan, yellowish-tan, or tan on the lighter end of the spectrum. Though the base color of the snake changes, the pattern of thick dorsal stripes remains the same. The stripes could be dark brown, charcoal-brown, brownish black, charcoal, or black at the dark end of the color continuum and become a medium greenish brown or medium reddish brown as the python shifts to the lighter end of the continuum. However, if a stripe is pure black it will remain black despite any other color changes. Though no newly hatched Halmahera pythons have been observed, Barker and Harvey of the 2000 python study “would predict that hatchlings are very dark reddish-brown in color.”