Oddly enough the only place on Mars we have seen outside the South Pole to have spiders is very close to the VIking 2 landing site. Right next to the lander enigmatic troughs were found similar to spider ravines. Scroll down to Viking spiders. No matter what people think the spiders are it is intriguing we may have inadvertedly landed on top of some remnants of them.

http://newfrontiersinscience.com/Members/v02n03/a/NFS0203a.shtml

"Oddly enough, Viking 2 [137] landed [138] nearly in the middle of a sub polar area that seems truly spider like [139]. Interestingly, some troughs were found near Viking 2 [140]. While other explanations have been suggested, the presence of the spiders nearby and their association with sometimes polygonal ravines makes these troughs possibly spider ravines. These "enigmatic troughs" [141] can be traced in a sequence of photos [142]. If they are spider ravines, it might indicate that when the spiders seasonally dissipate, they might leave ravines that are too shallow to see. There are also pits [143] in the area of unknown origin. In The Martian Landscape , Figures 195 [144],199[145], and 200 [146] may also be troughs. Figures 290, 210 and 211 [147] show paler areas devoid of rocks, which may be related to spiders. Of course, there are many other explanations but the proximity to the spiders makes these interesting. In imagery of the landing site [148], spider branches are 1-3 pixels wide where a pixel's width [149] is 9.46 meters [150]. Since spiders typically have a paler albedo and a comparable branch width to these pale patches, it is possible that they might be spider remnants."

http://history.nasa.gov/SP-425/ch28.htm