Introduced Green Anole In the Cayman Islands, But Which Species?

Green anole recently captured on Grand Cayman

This fella was caught a week and a half ago near North Side fire station, Grand Cayman. It’s the first green anole found outside the capital, Georgetown. The question: what is it? Anolis carolinensis? Anolis porcatus? Something else?

In fact, I frequently get asked whether a particular green anole is carolinensis or porcatus. Some people say they can tell them apart. I’m not so sure.

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

13 thoughts on “Introduced Green Anole In the Cayman Islands, But Which Species?

  1. I was actually on Little Cayman a few weeks ago. Fortunately, I didn’t see any green anoles on that island.

  2. I would put money on porcatus. Maybe even western porcatus. Look at those wide toe pads! The scapular ocellus with the white scales is like nothing seen in carolinensis, and the postorbital blotch is not as square. The black line through the eye is also unique to porcatus. Also, notice the dorsals: smoother, larger, and fewer in number than in carolinensis.

    The best way to distinguish carolinensis from porcatus is to put two, similarly-sized individuals of the same sex next to each other. You can really see the differences then. Big male porcatus look like carolinensis on steroids.

    I hope this doesn’t mean porcatus is established on Little Cayman. How will it compete with maynardi? (At the latter’s expense, I imagine…)

  3. Michael, you didn’t see any green anoles on Little Cayman? My house there is literally crawling with them. Where were you staying? my guess is one of the resorts that has lots of sand and few trees. A. maynardi is really quite abundant on LC and very beautiful.

    1. I don’t have experience with the Honduran populations, but the ear opening in this individual is not consistent with the tapered shape that is (mostly) diagnostic of A. allisoni on Cuba.

  4. Consider me among those who don’t believe that carolinensis and porcatus can reliably be distinguished. Having said this, I agree with Wes that big male porcatus are generally more impressive than even the largest A. carolinensis. This individual definitely has the look of a male porcatus to me.

    1. Thanks, Rich, for your comments. I envy your experience with wild porcatus in Cuba. I admit it’s a bit odd of me to be so obsessed with this species. I think it’s because, as a kid growing up in Hawaii, I spent a lot of time looking at carolinensis. I was trying to figure out what people like Shaw and Breese (1951), Oliver and Shaw (1953), Hunsaker and Breese (1967), and Cochran and Goin (1970) meant by “Anolis carolinensis porcatus,” and comparing this with the “Anolis porcatus” of Ruibal and Williams (1961) and Ruibal (1964). When I finally saw my first specimens of porcatus years later at the LACM, I could hardly believe my eyes! Even dead they looked SO different from any carolinensis that I had seen.

      By the way, many years ago I had the pleasure and privilege of meeting Dr. Rodolfo Ruibal before he retired from UC Riverside. It took me over an hour to drive out from L.A., and by the time I got there I was so nervous that I was literally trembling! It was embarrassing, but he was kind enough to listen to my story about wanting to study anoles and even took the time to show me around his lab!

  5. In my opinion, this is clearly Anolis porcatus. The scales on the gular sac of A. carolinensis are smaller in contrast with A. porcatus.

  6. Rich, I agree, I can’t see enough differences between carolinensis and porcatus to reliably tell them apart and am convinced that the population of Anolis carolinensis that have made a remarkable comeback in south Florida are actually a very fertile hybrid of both species. The Anolis carolinensis down here are very robust and do not flee from sagrei at all, they just seem to naturally prefer the tree canopies.

  7. I also think that it is difficult or impossible to distinguish U.S. Anolis carolinensis from U.S. A. porcatus in the field since you typically don’t have live, known A. porcatus for comparison. I think that Wes Chun is correct. Fully adult male A. porcatus and bulkier than A. carolinensis and I’ve seen some with what appear to be large bilateral calcium (?) deposits between the jaw and the neck that give them a bit of the look of a bulldog. I haven’t a clue how, for these two species, to distinguish subadult males and females in general. That shoulder bar (black; often with turquoise blue spots around the edges) is present in many populations of A. carolinensis in the Florida and further north and west, so it can’t be a reliable indicator of A. porcatus.

    In addition, most of the relevant research on these issues today concentrates on spectral analyses of skin and dewlap colors, sometimes comparing these to spectral characteristics of the habitat which the lizards occupy. It’s time for a little old school field work. We need detailed narrative descriptions of color AND pattern of live A. carolinensis obtained under controlled conditions of light and temperature and in the maximum green and maximum dark color phases, and of patterning in both color phases, and these data need to be representative of populations across the entire mainland range of the species. If done by multiple investigators, these studies need to employ the same methods and standards. Geographic variation is obvious. Most A. carolinensis have pink to reddish dewlaps but those in southwestern Florida are grayish or greenish, I found a small population between Corkscrew Swamp Sanctuary and Immokalee, FL with pale orange dewlaps, and some males on Oahu, HI have lilac-colored dewlaps. As noted above, the shoulder patch can be entirely absent in a population or present but in frequencies that differ among populations. In East Tennessee, animals in the maximal dark phase are very dark brown to nearly black with no patterning (except a pale venter) whereas those near Gainesville, FL are a gray with a filigree pattern that is whitish in color. The frequency of females with pale middorsal stripes varies among populations. In a part of Withlacoochee State Forest, FL and in the green phase, the color is “chalky” green, along the coast near Ft. Myers it is a beautiful emerald green, further north, as far as Tennessee, it is more of a leafy green. As important as they are, spectral studies usually don’t mention pattern at all, and are carried out only in the green phase. Further, spectral values are of little value to someone working in the field not well versed in visualizing what they mean in the context of the lizard they are holding. I say all of this despite having a friend who is heavily invested in spectral studies. With all of this variation, and without having comparable data for A. porcatus, I’m not sure that we will ever be able to identify in the field with 100% certainty whether a green anole in South Florida (or the Cayman Islands) is A. carolinensis or A. porcatus with the possible exception of a large male A. porcatus with “calcium” deposits.

    But I guess I could be wrong.

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