PATERNAL CARE IN A NEOTROPICAL HARVESTMAN, ZYGOPACHYLUS-ALBOMARGINIS (ARACHNIDA, OPILIONES, GONYLEPTIDAE)

Males of the tropical harvestman Zygopachylus albomarginis guard eggs inside open mud nests that they build, usurp or occupy if abandoned. They maintain the nests for extended periods by removing fungus, repairing them when damaged, and guarding them from conspecifics and ants. Females wander on tree trunks and visit nests; they actively court males, mate and oviposit inside the nests and then leave. A male guards a nest with eggs of different ages and from different females. This behaviour may be unique among arachnids. There was considerable variation in numbers of eggs that males guard throughout the breeding season. This variability could not be explained in terms of obvious characteristics of nests or males. An experiment in which males were removed from nests showed that nest guarding by males is essential for egg survival. This system has not been described in detail before and remains the only known case of paternal care in arachnids. © 1990 The Association for the Study of Animal Behaviour.