Halmahera python

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Halmahera python
Morelia tracyae.jpg

Halmahera python(Simalia tracyae)

without rank: Toxicofera
Submission: Snakes (Serpentes)
Superfamily: Pythones (Pythonoidea)
Family: Pythons (Pythonidae)
Genre: Amethyst pythons(Simalia)
Art: Halmahera python
Scientific name
Simalia tracyae
(Harvey, Barker, Ammerman & Chippindale, 2000)

The Halmahera python(Simalia tracyae, Syn.: Morelia tracyae) belongs to the python family (Pythonidae). The species was separated from the amethyst python only in 2000. Almost nothing is known about the biology of these snakes, which are apparently only native to the northwestern arm of Halmahera.


Physique and length

The Halmahera python is a slender, yet quite powerfully built python. The long tail accounts for up to 19% of the total length. The head is clearly set off from the neck and is distinctly broadened in adult females. The eyes are located on the sides of the head and are slightly forward. The rounded snout, which is semi-oval when viewed from above, is longer in males than in females. The round nostrils sit obliquely between the top and side of the head. As the species could only be studied on the basis of a few individuals so far, no data on the average and maximum length of adult animals are available yet. The largest animal studied so far was a male with a total length of 2.93 meters. However, it is assumed that the species can reach a maximum total length of at least 4 meters.


The rostrale (snout shield), which is only moderately visible from above, has, as in most other pythons, two deep labial pits reaching to the edge of the shield. The nostrils are each positioned in the upper posterior part of the large nasale (nasal shield). From the nostril to the posterior margin of the shield a well recognizable suture runs. Towards the middle of the head, the nasalia are separated by a large pair of internasalia (intermediate nasal shields). From the tip of the snout along the midline of the top of the head, the internasalia are followed by a large, more broad than long anterior pair of prefrontalia and a smaller posterior pair of prefrontal shields. The posterior pair of prefrontalia may occasionally be separated by a small shield. Behind it follows a simple large frontal (forehead shield) and then two to three pairs of species-characteristically large parietalia (parietal shields). Of these, the anterior one is in close contact across the midline of the top of the head, at least in the anterior half, while in some animals the posterior ones are separated by two to three small interparietalia (intermediate parietal shields). The occipitalia (occipital shields), which are located even further towards the nape of the neck, are small in this species and of the same size as the adjacent nuchealia (nuchal shields).

Above each eye there is a large triangular supraocular (over-eye shield). Preocularia (fore-eye shields) exist in two, postocularia (hind-eye shields) in four. Subocularia (lower eye shields) are missing in this species.

On the side of the head between the eye and the nostril are lorealia (bridle shields) arranged in two rows. Of the 13 supralabialia (upper lip shields), the anteriormost five bear deep labial pits on their posterior margin, with the labial pit size decreasing towards the corner of the mouth. Supralabialia 6 and 7 also touch the lower margin of the eye. Infralabialia (lower lip shields) there are 20, the anteriormost of which bear two faintly discernible labial pits and pits 9 to 16 deep labial pits. The chin pit consists of shieldless skin.

The number of ventralia (abdominal shields) varies between 316 and 326, the number of dorsal scale rows in the middle of the body between 47 and 49. 96 to 100 only partially paired subcaudalia (tail underside shields) are found from the cloaca to the tip of the tail. The anal (anal shield) is divided into two parts.


Compared to other “amethyst pythons”, the Halmahera python is very uniformly colored and patterned. No unpatterned animals are known from this species. The ground color is normally brownish, orange-brown, to reddish-yellow and can be lightened by environmental factors within hours into a light greenish beige, beige-grey or beige. Of all the amethyst pythons, the Halmahera python has the broadest and most distinct dorsal pattern. Running along the body at intervals of 3 to 7 shields on either side of the spine are 48 to 56 dark dorsal spots, up to 11 shields wide and 15 shields long. On the first third of the body, the dorsal patches run separately, keeping a lightened stripe free on the spine of single individuals. As the body progresses, fusions between dorsal spots increase across the spine. The dark flank spots are more numerous, only about two-thirds as large as the dorsal spots and offset from them. Towards the tail the back and flank spots merge more and more and form 16 to 23 mostly continuous rings on the tail. Back and flank spots are black bordered, of dark brown, chocolate brown, dark grey, brown-black to completely black colour and become increasingly lighter from the back to the flanks. In animals of the light phase the black portion of the spots remains constant, only the core changes colour to greenish brown, reddish brown to brown.
The underside of the body is monochrome grey-white and becomes slightly darker towards the tail. Only at the edge of the belly the dark flank spots are still partially bordering. The pattern visible on the upper side of the tail is somewhat lightened on the underside of the tail.

The top and side of the head are slightly lighter and more yellow than the body base color. Many of their shields are framed by a fine black line. Lip and chin shields are pale yellow or white-gray and have no dark border. The throat is uniformly white-grey.
In most animals an indistinct, dark yellow-brown stripe extends from the forehead to the posterior margin of the eye and runs from there as a band two to three shields wide to the corner of the mouth. The contrast of this band is primarily emphasized by dark edges of tangential shields. A black, well defined nuchal band runs across the back of the head from muzzle angle to muzzle angle. This may be interrupted in the middle of the top of the head. Occasionally a second, parallel posterior nuchal band or a simple nuchal patch is also present.
Of all the amethyst pythons, this species is the only one to possess a red iris. Each individual is capable of matching its iris color to the brightness of the body from dark reddish brown, orange brown, or brown to a dark golden brown or light reddish brown. The tongue of this species is solid blue-gray or black.

Color change

The ontogenetic color change is very low in the Halmahera python. Juveniles are only slightly darker colored than adults.


The lifestyle of the Halmahera python is still unexplored. So far, only snake catchers of Halmahera could tell us that the species lives mainly on trees and is occasionally found on the ground. Very often these pythons are said to be in the vicinity of flying fox colonies, on which they also feed.
The Halmahera python shares its range solely with another giant snake, the reticulated python.


Distribution area of the Halmahera python (purple), Tanimbar python (black), Seram python (blue), as well as the New Guinea python (red, dark & light orange, yellow) and Australian amethyst python (green)

The amethyst python was first described by Schneider in 1801 under the scientific name Morelia amethistina. In 1933, Stull assigned subspecies status to the Australian population as Morelia amethistina kinghorni. In 2000, Harvey et al. differentiated five distinct species considering morphological, biogeographical and molecular genetic aspects: Morelia amethistina, Morelia kinghorni, Morelia nauta, Morelia clastolepis and Morelia tracyae. All amethistine pythons described so far inhabit spatially separated habitats (allopatry). However, it is assumed that among the species described so far, further species can be differentiated, some of which even inhabit the same areas (sympatry). This is especially suspected in New Guinea and New Ireland.

It is assumed that once a primitive form of the amethyst pythons lived on the nascent New Guinea. Millions of years ago, the islands of Halmahera and New Ireland were separated from New Guinea by deep ocean straits, completely isolating the amethyst python populations there. During later ice ages, low sea levels formed land bridges between New Guinea and neighboring islands and the Australian mainland. Thus, in a second phase, amethyst pythons colonized the D’Entrecasteaux Islands, the Louisiade Archipelago, Aru. Seram, Ambon, Yapen, offshore islands of the Torres Strait and northern Australia. By means of driftwood, these pythons were then able to move in a third phase from Aru to the neighbouring island of Kai, and those from Yapen to the neighbouring island of Biak. The Tanimbar Islands also never had contact with other land masses, which means that precursors of this population must also have colonized the islands by water. Since New Guinea was also still undergoing major geotectonic changes, the original form of the amethyst python was also able to differentiate locally here.

These pythons are most closely related to the Boelen python(Morelia boeleni). The characteristic common feature of amethyst and Boelen pythons is the presence of at least two pairs of large parietal shields. In 1984 Wells & Wellington[1] proposed to separate amethyst pythons from rhombic pythons(Morelia) as a distinct genus named Australiasis.

However, the genus name Australiasis is invalid because the genus was described in a journal that does not conduct peer review.[2] Therefore, in early 2014, the generic name Simalia (Gray, 1849) was introduced for a new genus composed of the Boelen python, the Oenpelli python and the Amethyst pythons.[3]

According to Harvey et al. (2000) and Reynolds et al. (2014), the relationships are as follows:


Oenpelli’s python (Simaliaoenpelliensis)

Boelen’s python (Simaliaboeleni)

Halmahera python(Simaliatracyae)

“Simaliaamethistina” (New Ireland)

“Simaliaamethistina” (Northwest New Guinea)

Seram python (Simaliaclastolepis)

Australian amethyst python (Simaliakinghorni)


Simalia tracyae received the species epithet tracyae in honor of Tracy M. Barker. Together with her husband David G. Barker, she has been considered a luminary in the field of breeding and keeping rare giant snakes for years. Their large joint amethyst python collection, which has existed for over 10 years, contributed significantly to the description of the five amethyst python species by Harvey et al. 2000.


Individual references

  1. R. W. Wells, C. R. Wellington: A classification of the Amphibia and Reptilia of Australia. Australian Journal of Herpetology, Supplementary Series, issue 1, 1984 pp. 1-61, full text@1@2Template:Dead link/ no longer available, search web archives ) Info: Thelink was automatically marked as broken. Please check the link according to the instructions and then remove this notice.
  2. Hinrich Kaiser, Brian I. Crother, Christopher M. R. Kelly, Luca Luiselli, Mark O’Shea, Hidetoshi Ota, Paulo Passos, Wulf D. Schleip, Wolfgang Wüster: Best Practices: In the 21st Century, Taxonomic Decisions in Herpetology are Acceptable Only When Supported by a Body of Evidence and Published via Peer-Review. In: Herpetological Review, 2013, 44(1), 8-23. 44, 2013, S. 8–23.
  3. R. Graham Reynolds, Matthew L. Niemiller, Liam J. Revell: Toward a Tree-of-Life for the boas and pythons: multilocus species-level phylogeny with unprecedented taxon sampling. Molecular Phylogenetics and Evolution, Volume 71, February 2014, Pages 201-213, doi: 10.1016/j.ympev.2013.11.011


  • M. B. Harvey, D. G. Barker, L. K. Ammerman, P. T. Chippindale: Systematics of Pythons of the Morelia amethistina Complex (Serpentes: Boidae) with the Description of three new Species. Herpetological Monographs 14, 2000, pp. 139-185.

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