Sexual dichromatism and male colour morph in ultraviolet-B reflectance in two populations of the jumping spider Phintella vittata (Araneae: Salticidae) from tropical China

In the literature on animal use of ultraviolet (UV) vision and UV reflectance, it has usually been UV-A (315–400 nm) that is considered. Animals are generally assumed to be unable to discriminate UV-B (280–315 nm) from other wavelengths in natural sunlight. Recently, some animals are known to be able to detect and respond directly to UV-B in order to avoiding exposure to it. However, there is no evidence that the hue corresponding to UV-B is salient to an animal during intraspecies communication. Using Phintella vittata , an ornate jumping spider from two geographically different populations in China, we investigated geographical, intersexual, intrasexual, and interpopulation variation in UV reflectance. We found that both the males and the females of P. vittata reflect UV light, and that the reflection bands are located in UV-B, a part of reflectance spectrum never previously investigated. We also found a great deal of population variation in the UV-B spectral reflectance. Furthermore, two colour morphs, the 'green' and 'yellow' morphs, are identified for adult males for both populations, and both morphs differ greatly in both UV-B and human-visible wavelengths. This is the first demonstration of a UV-B reflecting salticid and UV-B sexual dichromatism.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 7–20.