by Joseph DeSisto
I haven’t written in a while, and it’s time to say why: for the last few weeks, my dad and I have been travelling around the southeastern United States in search of centipedes. Specifically, we were looking for specimens of a new species of centipede I am working on describing, but we ended up seeing many more amazing things — worm snakes, scorpions, giant millipedes, and velvet ants, just to name a few.
The next few articles to appear on Beautiful Nightmares will focus on some of my favorite finds, starting with some of my favorite lizards, the skinks. Here’s a five-lined skink (not my photograph):
Five-lined skinks (Plestiodon fasciatus) and their relatives undergo amazing transformations in color through their lives. The individual above is an adult male, but females and juveniles are far more visually stunning, with well-defined yellow lines on a black background and an electric-blue tail.
The tail serves to distract predators from more vulnerable parts of the body — while an attack to the head would likely be fatal, a bird that picked at the lizard’s blue tail would quickly discover that five-lined skinks can drop their tails to make a hasty escape. The tail may even continue to wriggle enticingly long after its owner has darted into hiding.
Most of the lizards we saw were five-lined skinks … we think. In truth, although five-lined skinks are the most abundant skinks in the southeast, they are easily confused with two closely related members of the genus Plestiodon. The broad-headed skink (Plestiodon laticeps) and the southeastern five-lined skink (Plestiodon inexpectatus) both are difficult to tell apart from the five-lined, so much so that the southeastern five-lined wasn’t formally described until 1932!
Telling these lizards apart generally requires a close look at the scales on the head and/or tail. Unfortunately for me, skinks are fast and alert, and catching one is a formidable challenge, but photographs can help. Take a look at the five-lined skink below — you can click on the image to see a larger version.
To tell that the skink above is not a broad-headed skink, we can look at the labial scales. These are the roughly square-shaped scales bordering the mouth, on the upper lip. The first labial scale is beneath the nostril, followed by three more scales proceeding along the upper lip toward the eye. The longer rectangular scale, positioned along the mouth and directly beneath the eye, is the first one that is not a labial scale. Since this skink has four labial scales, we know that it is not a broad-headed skink, which would have.
However, this still leaves the possibility that this is a southeastern five-lined skink. To tell apart five-lined from southeastern five-lined skinks, we need to look at scales again, this time beneath the tail:
Again, you may have to click on the image to see a larger version. The scales running down the middle of the tail are wide and not divided along the mid-line. This tells us we are indeed looking at a five-lined skink; in the southeastern five-lined, the scales running down the middle of the tail’s underside are divided.
If you’re still with me, congratulations! You can now distinguish the three Plestiodon species in the southeastern United States that look like five-lined skinks — that is, if you manage to catch one.
I learned these identifying features from the Peterson’s field guide to the eastern and central North American reptiles and amphibians (Conant and Collins 1998). It is cited below. I have looked at quite a few field guides and this one is the best for the field naturalist, hands-down. The taxonomy is a little outdated, for example Plestiodon is referred to by the old name Eumeces, but this can easily be forgiven. If you are interested in identifying reptiles and amphibians in the field, I highly recommend purchasing a copy.
Conant R. and J.T. Collins. 1998. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. New York, New York: Houghton Mifflin Company, 1998.