Formerly, five [[subspecies]] of ''Morelia amethistina'', including the nominate race, ''M. a. amethystina'', were generally recognized. The [[Moluccan Islands,]] (including [[Halmahera]], [[Ternate,]] and [[Tidore,]]) are home to the former ''M. a. tracyae''. The [[Tanimbar Islands]] are home to a smaller subspecies, the former ''M. a. nauta''. On the island of [[Seram]], the former ''M. a. clastolepis'' can be found. On mainland of [[Papua New Guinea]] (including the Indonesian western half, once called Irian Jaya—now [[West Papua]]), and many of its nearnearby offshore islands, the former ''M. a. amethystina'' is quite common. In Australia, the former ''M. a. kinghorni'' is represented.<ref name="ITIS">{{ITIS |id=634775 |taxon=''Morelia amethistina'' |access-date=18 September 2007}}</ref> American biologist Michael Harvey and colleagues investigated the amethystine python complex and recognised five separate species{{snd}} ''Simalia amethistina'', ''[[Simalia clastolepis]]'', ''[[Simalia kinghorni]]'', ''[[Simalia nauta]]'', and ''[[Simalia tracyae]]''{{snd}} based on cladistic analysis of cytochrome b sequences and morphology.<ref name="Harvey2000">{{cite journal | first = Michael B. | last=Harvey | first2 = David G. | last2=Barker | first3 =Loren K. | last3=Ammerman | first4 = Paul T. | last4=Chippindale | title=Systematics of Pythons of the ''Morelia amethistina'' Complex (Serpentes: Boidae) with the Description of three new Species | journal= Herpetological Monographs | volume=14 | year= 2000 | pages= 139–185| doi= 10.2307/1467047|url=https://www.researchgate.net/publication/256197534_Systematics_of_Pythons_of_the_Morelia_amethistina_Complex_Serpentes_Boidae_with_the_Description_of_Three_New_Species}}</ref> In 2014 cladistic analysis of nuclear and mitochondrial genes of pythons and boas, R. Graham Reynolds and colleagues supported the distinctness of ''M. tracyae'', ''M. amethistina'', and ''M. clastolepis'', but were less confident of ''M. kinghorni'' and ''M. nauta''.<ref name="Reyn01">{{cite journal |last=Reynolds | first= R. Graham|last2=Niemiller | first2= Matthew L. |last3=Revell | first3= Liam J. |title=Toward a tree-of-life for the boas and pythons: multilocus species-level phylogeny with unprecedented taxon sampling |year=2014 |journal=Molecular Phylogenetics and Evolution |volume=71 |pages=201–213 |doi=10.1016/j.ympev.2013.11.011 | url=https://www.researchgate.net/publication/259246220_Toward_a_Tree-of-Life_for_the_boas_and_pythons_Multilocus_species-level_phylogeny_with_unprecedented_taxon_sampling}}</ref>
According to McDiarmid ''et al.'' (1999), all cases in which the [[Specific name (zoology)|specific name]] was spelled with a ''y'' follow Daudin's (1803) ''Python amethystinus'' and are therefore unjustified emendations.<ref name="McD99"/> The [[Specific name (zoology)|specific name]], ''amethistina'', is an allusion to the milky iridescent sheen on its scales, which gives it an [[amethyst]]-like colour.
