I have often explored observations of snakes on iNaturalist.org as one way of getting a clearer idea of where they occur in their native ranges and what kind of habitats they occupy. Occasionally, observations posted on the site reveal even more.
In this case, an observation posted by the user Samy Lima, shows perhaps the first account of male-to-male ritual combat in Spilotes sulphureus which has been documented in photographs:
Though well documented in Spilotes pullatus, very little, if anything, has been published recording the behavior in sulphureus.
I have observed this behavior in captive specimens on two occasions, after introducing two large males (one of which was thought to be a female at the time). In both instances, the slightly larger male asserted dominance by elevating above and forcing the other male's head to ground, and the submissive male immediately sought to flee. In the first instance observing this, I thought the behavior might be courtship, given that the snakes had been represented to me as a male and female. However, after observing it a second time, I felt all but certain that both snakes were males and that I was actually observing male-to-male combat to assert dominance. I separated the snakes and later confirmed that to be the case.
In wild snakes, ritual combat between males is largely associated with asserting dominance and breeding access to a female, and in may recorded cases of the behavior a female was observed nearby. However, a number of cases have also been observed without a female present and well outside of the expected breeding season, suggesting that ritual combat could serve other functions - perhaps related to territory disputes.
For more reading on the behavior in pullatus, check out this article.