The Dark Boas. Anerythistic, Leopard and IMG
Anerythistic boas
For many years, the darkest boas available were Anerythristic boas, commonly known as “Anery.” In contrast, Anerythristic Corn Snakes are often called “Silver Corns,” but boas never received such a nickname. Anerythristic refers to the reduction or elimination of red pigment in the skin. Some Anery boas, such as Type 1 Anery, retain faint traces of reddish-brown, while others, like Type 2 Anery, Carbon, and Black-Eyed Anery, lack red pigment entirely. These different Anery genes are not compatible, so breeding two distinct lines of Anery results in double-heterozygous offspring rather than visual Anery boas.
In South Africa, 99% of Anery boas are Type 1, one of the earliest discovered but not the most striking form. Type 1 Anery boas still display remnants of red and brown, whereas some other Anery genes produce only black and gray. Anery boas are a recessive trait, meaning both parents must either carry or express the gene for it to appear in offspring. They are essentially the opposite of Kahl Albinos.
Anery boas are a key component in producing Snow boas (Anery + Albino) and Moonglow boas (Anery + Albino + Hypo). When combined with Hypo, they create Ghost boas. Since Hypo has a super form, it can produce Super Ghosts, which are only slightly paler than Ghosts but guarantee that all offspring inherit the Hypo trait.
When mixed with Motley, Anery boas produce darker offspring, but the difference is subtle because Motley boas are naturally dark.
Leopard Boas
Another group of dark boas is the Leopard boas. Originally believed to be a recessive trait with slightly visual heterozygous offspring, it is now understood to be an incomplete dominant gene. However, many people still refer to heterozygous Leopard boas as “het Leopards.” The key distinction is that there is no such thing as a 66% possible het for Leopard. Instead, an uncertain specimen should be labelled as “poss Leopard,” similar to how Jungle boas or other incomplete dominant genes are categorized.
Leopard boas exhibit a wide range of patterns and speckles, with no two looking exactly alike. As their name suggests, they feature spots along the body rather than the typical bowtie or saddle patterns. The original Leopard boas were imported from Sonora, Mexico, by Hans Winner. He proved their genetics, but the original shipment contained three distinct lines (or genes): Leopard, Stars & Stripes, and Sonoran IMG. Over time, the distinction between these lines blurred, and many now consider Stars & Stripes to be a variation of the Leopard boa. The Sonoran IMG gene, however, breeds true and has been documented to produce super forms.
Despite their dark coloration, Leopard boas often have a pink or red undertone, which is especially pronounced in Hypo and Albino versions. Hypo Leopard and Super Hypo Leopard boas are particularly striking, and Ghost Leopards are an uncommon but beautiful morph.
Leopard boas can be crossed with Black Boas from Costa Rica and Onyx Boas from Honduras. While these boas have distinct appearances, they can interbreed to produce Mystique Boas or Black Leopards, which are almost completely black. When bred to Motley boas, they produce “het Eclipse” boas—dark, minimally patterned snakes. If both Leopard and Motley genes are homozygous, the resulting Eclipse boa is even darker. Although both Leopard and Motley are incomplete dominant traits, the term “het Eclipse” persists in the reptile community despite not being technically correct.
Identifying “het Leopards” can be challenging, particularly when other genes are present. However, they typically have dark eyes and connected saddles that form a diamond pattern. Leopard boas are relatively small due to their Sonoran lineage and should not be overfed, as they can develop digestive issues—a common concern with Central American boas.
IMG Boas: The Darkest of Them All
The darkest morph of all is the IMG (Increasing Melanin Gene) boa. These boas start slightly darker than their siblings and become progressively blacker with each shed. They are also known as Azabache boas, with the most famous example being “Midnight Gin,” which turned nearly jet black. Despite different names, all IMGs appear to share the same genetic origin.
Pete Kahl (of Albino Boa fame) discovered the IMG gene in a particularly dark Anery boa from one of his litters. He held back the boa and bred it to a Sunglow, ultimately confirming that it was an entirely new gene. Over time, the Anery influence in IMGs has been diluted through selective breeding. However, when combined with Black-Eyed Anery, IMG boas become even darker, creating what is known as a “Black Devil” boa.
IMG boas mixed with Motley produce intensely black boas that can be identified after their first shed. When combined with T- Albinos (such as Kahl Albinos), the result is a much whiter boa. When paired with T+ Albinos (such as VPI Albinos), they initially appear dark purple and brown but often develop a less appealing coloration over time. Some breeders introduce Hypo into IMGs, but this contradicts the goal of producing a fully black boa, resulting in what are sometimes referred to as “dirty” boas.
