First case of color dimorphism in pholcid spiders
(published in J. Arachnol, 2004. see Abstract, PDF)
 

We present here the first case of a color polymorphism in the spider family Pholcidae, based on large series (1139 specimens) of the east African Buitinga safura. About 6% of specimens have large black spots on the abdomen, all others are spotless.

Photo: B. A. Huber