Lek behavior in hypercephalic Zygothrica dispar Wiedemann (Diptera, Drosophilidae)

In the Neotropical drosophilid secies Zygothrica dispar the males, many of which are hypercehalic, engage in territorial fights on mushrooms. In an attempt to see whether head width effects mating success, lek behavior was videorecorded. Most owners of a territory on the cap of a mushroom are broad-headed, and usually defeat intruders, which in general have a narrower head. Escalation in confrontation to bodily contact is rare and mostly involves opponents of equal head width. Most contests between unequals end after a close head-to-head confrontation, and are thus purely ritual. Females appeared to be courted only on the lek. Although no female was observed to copulate, it can be supposed that male head width influences fitness through its effect on owning a territory on the lek.