For all the color and pattern variations of Florida’s Eastern garter snakes, Banded watersnakes, Eastern rat snakes, and even Florida cottonmouths, one species that simply doesn’t carry too much variation in its adult form is the Southern black racer, Coluber constrictor priapus. As adults, Southern black racers in Florida tend to sport smooth, black dorsal scales with a black face, a slightly lighter (even brownish) nose, and a white “chin” (the scales beneath the lower jaw). I simply don’t see much variation in Florida’s Southern black racers base pattern, but there is one notable exception…
In peninsular Florida, we have a commonly recognized second subspecies of racer: Coluber constrictor paludicola, the Everglades racer, which sports a grayer dorsal pattern. This subspecies ranges throughout stretches of south Florida and —inexplicably— coastal Brevard county in central Florida (the Merritt Island area, home to NASA’s Cape Canaveral). Personally, I’m not sure I buy that the Everglades racer is actually (or, rather, should be) a distinct subspecies. That classification is based on a 1950s publication which based its taxonomical division solely on physical appearance (such as color, luster, and scale counts). I suspect so-called Everglades racers may simply be Southern black racers with a bit more of a grayish dorsal phenotype coupled with other minor variations.
A 2007 study by Burbrink et. al (Phylogeny across a continent: The evolutionary and demographic history of the North American racer) noted that peninsular Florida racers do indeed share a common lineage distinct from those of Georgia, Alabama, and all the rest, and argues no further division of subspecies within the peninsula. Mainstream culture, however, continues to hang on to the Southern/Everglades split in Florida — for the time being. Whatever the case, I’ll have to wait there’s more genetic research and overall consensus negotiating the difference, if any, between the two supposed subspecies.
Now, if we do consider Southern black racers as distinct from Everglades racers, then there truly isn’t much variation in Florida’s Southern black racers. They pretty much always look just like Southern black racers, more or less. The nose is the where most of the variation is, and that’s about it. However, in southern Georgia, the Southern black racers can be quite distinct from their Floridian brethren. From 2011 through 2013, I came across a decent number of Southern black racers that sported a mottled-chin pattern (as seen in this post) — much darker than their Floridian brethren. I don’t believe I’ve ever seen this kind of patterning in a south or central Florida racer (though I’m sure they exist here and there).
The Burbrink study referenced and linked earlier also noted that the Georgia racers were of a separate lineage than the Florida racers… If this holds with further testing and verification, the phenotypic variation of the mottled-chin may simply be more common in that lineage of racers — and less so with the Florida lineage (regardless of whether you want to call them separate subspecies or whatever).
Racers can be wickedly common throughout their considerable range. They’re one of the larger serpent species to do really, really well in human-habitated areas. With excellent visual acuity, speed, and dexterity, racers can scratch out a pretty good living in the suburban wilds of our backyards. As common as they may be, however, I’m always thrilled to spot one in Florida — perhaps because I’m hoping to find some kind of variation… maybe something that echoes those gorgeously strange south Georgia racers with the mottled chins.