Courtship and male-male agonistic behaviour of Cosmophasis umbratica Simon, an ornate jumping spider (Araneae: Salticidae) from Singapore

Abstract

The courtship and male-male agonistic behaviour of Cosmophasis umbratica Simon, an iridescent jumping spider from Singapore, was studied for the first time. Exhibiting sexual colour and size dimorphism, C. umbratica is frequently found on leaves and flowers of tropical plants in open areas. Males are generally larger than females and dominantly green and black with silvery white markings; females are generally a mixture of green, brown, white and black. Sixteen major displays are described for C. umbratica. Skittering, vibrating of palps, arching of legs and flexed up abdomens are dominant male behaviours during courtship. Females almost always decamp on first sight of males, although males are very persistent in their courtship. A large repertoire of male-male agonistic displays is observed, with males either decamping after a clash, being lifted up and thrown down, or while embracing are chased away after being pushed back. Drumming is also displayed in both male-female and male-male interactions. This vibratory communication channel during inter- (male-female) and intra-sexual (male-male) interactions away from nests is discussed in regards to the evolution of salticids. © National University of Singapore.