Crablike Spiny Orbweaver: Color Variation from West Indies

Gasteracantha cancriformis
Hi Daniel and Lisa,
Here is a shot taken on our trip to Nevis, West Indies at the end of April this year. I am assuming this is Gasteracantha cancriformis , even though it has two less spines than the images from the US. There were a whole lot of these neat little spiders in their big scraggly-looking webs, spun across the back patio of one of the hotel rooms we stayed in, which was close to the beach. All of the spiders had yellow abdomens. I would not been able to recognize this spider, if not for reading your site, so thanks!
Susan J. Hewitt

Hi Susan,
We are not thoroughly convinced that this Crablike Spiny Orbweaver is Gasteracantha cancriformis, but we are pretty certain the genus is correct. G. cancriformis has quite a bit of individual variation, so perhaps you are correct. The coloration on your specimen is stunning.

Yes, it is kind of different from the US specimens. On Wikipedia someone has attempted to list all the Gasteracantha species worldwide, and that list gives G. cancriformis as the only “New World” species. However it also lists a subspecies, Gasteracantha cancriformis gertschi , as the US taxon, so maybe that is why it looks a bit different? The other possibility is that at least in the case of snails, some of the Caribbean islands have had the opportunity to develop local forms and even endemic species, having been rather isolated for so long. Come to think of it I can e-mail a friend of a friend who is doing a doctorate on spiders at University of the West Indies, and see if she knows.

Update from a Spider Expert: (06/08/2007)
Hi Susan,
It is no bother. That is Gasteracantha cancriformis. Although the ones you saw were yellow they vary in colour so that some are white, red, orange or totally black. This the most common tropical species and is most likely the only species in the Lesser Antilles. With respect to the number of spines there are usually 6 spines but the anterior pair may have broken off or may be minute. Hope this is informative. Regards,
Jo-Anne N. Sewlal,
Dep’t of Life Sciences
University of the West Indies
St. Augustine, Trinidad and Tobago

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