Comparative study of courtship and copulation in five Oedothorax species

Oedothorax gibbosus (Blackwall, 1841) is a dwarf spider restricted to oligo- and mesotrophic alder carrs. This dwarf spider is distinguished from other Oedothorax species by its male dimorphism; gibbosus males are characterised by a hunch and a hairy groove on their carapace, tuberosus males do not have these features. The hairy groove is important during gustatorial courtship behaviour; this is the uptake of secretions by the female from a male body part during courtship. Another remarkable difference between O. gibbosus and its sister species is that courtship and copulation duration is much longer in this species. The rare O. gibbosus spiders also seem to be less active than common spiders of O. fuscus (Blackwall, 1834), O. retusus (Westring, 1851) and O. apicatus (Blackwall, 1850). In that way common spiders raise their chances of survival in the open field. A more active lifestyle seems to be related to a shorter, heavier courtship and copulation. It is also possible that the longer courtship and copulation time, useful for male competition and sperm competition, results from the male dimorphism in this species. The web has an important function in the reproduction of Oedothorax spiders : it is necessary during gustatorial courtship, other courtship activities and copulation, and it is also probably important for the distribution of contact pheromones. The copulation of Oedothorax species differs from that of Erigone : instead of two continuous insertions, we observed, in this case, a series of very short insertions, which can be linked to one other to make up longer periods.