Chelicerae as male grasping organs in scorpions: sexual dimorphism and associated behaviour.

Specialised structures that enable males to grasp females during sexual interactions are highly susceptible to selection and thus diverge relatively rapidly over evolutionary time. These structures are often used to test hypotheses regarding sexual selection such as sexually antagonistic co-evolution and sexual selection by female choice. In the present study, we determine whether there is a relationship between a novel record of scorpion sexual dimorphism, the sexual dimorphism of chelicerae (CSD), and the presence of the mating behaviour termed "cheliceral grip" (CG).

Chemical defense in harvestmen (arachnida, opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators?

Two alkylated 1,4-benzoquinones were identified from the defensive secretion produced by the neotropical harvestman Goniosoma longipes (Gonyleptidae). They were characterized as 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. We tested the effectiveness of these benzoquinone secretions against several predator types, including invertebrates and vertebrates.