The "traditional" separation of Heloderma suspectum into the two distinct subspecies H. suspectum suspectum and H. suspectum cinctum was based on patterns and distribution (see map!). This no longer valid. The difference in mtDNA expression (mitrochondrical base sequence divergence) of individuals from the most northern and nearly most southern populations (Hermosillo, Sonora, Mexico) with a distance of 650 Miles differ only by 0,5%. The banded reticulate dichotomy does not portray geographic pattern that normally indicate distinct subspecies (Ref. 18).
There is a tendency to believe that specimens of the northern distribution area are more banded and lighter in color, although dark speciems (coloration like Hermosillo) were collected in southern Utah. If bands partially break up they form large yellow/orange areas which could be evenly dotted in between the bands (formally H. s. cinctum). Gila Monsters out of the more southern range might expose more reticulate (e.g. dotted bands) patterns (Ref. 2).
The impression is that of a reticulated pattern. Independent from their origin, all hatchlings show a banded pattern (Ref. 2). The most impressive change happens within the first six months after hatching. The patterns on their heads do not undergo significant changes while reaching maturity.
Examples of pattern changes of Heloderma suspectum of the southern distribution area:
Photographs of four of my own captive born hatchlings and their growth rate at 6,12 and 24 month.
Examples of pattern changes in Heloderma suspectum of the northern distribution area:
Photographs of three US imported specimens at hatching and their growth rate at 6,12 and 24 month.
Additionally, their photographs document weight gain, growth in length (SVL) and total length.
Examples of different patterns of the head of Heloderma suspectum:
In "contrast" to the change of body patterns, the patterns of the head are very consistent. A field biologist or a keeper will be able to easily identify different specimens still after years (Ref. 34).
