Reproductive biology of the neotropical harvestman (Goniosoma longipes) (Arachnida, Opiliones : Gonyleptidae): mating and oviposition behaviour, brood mortality, and parental care

Goniosoma longipes is a neotropical cavernicolous harvestman that exhibits parental care. Reproductive activity in G. longipes is more intense during the wet season. Mating lasts up to 3 min, and the whole oviposition process may take over 5 h. During oviposition the female may be reinseminated once or twice by the mating male. Females oviposit 60-210 eggs on the cave wall and guard egg batches for nearly 2 months, until the 1st-instar nymphs dis perse. Four main factors can affect egg survival in G. longipes: dehydratio n, fungal attack, cannibalism, and interspecific predation. Frequency of fu ngal attack on egg batches was greater in the wet season and more intense n ear the river inside the study cave. Although egg-guarding by females faile d to prevent fungal attack on eggs in G. longipes, the choice of a suitable oviposition site by the gravid female can reduce fungal attack within the cave habitat of this species. Guarding females successfully repel conspecif ic egg predators, but unguarded eggs are frequently consumed by adult and j uvenile G, longipes, as well as cave crickets Strinatia sp. Field experimen ts in which females were removed from egg batches demonstrated that egg-gua rding by the mother has an anti-predator role in G. longipes, with a signif icant positive effect on egg survival. Male G. longipes actively patrol the ir egg-guarding mates, and take over brood care for up to 2 weeks if the la tter are experimentally removed. The degree to which male assistance can pl ay a relevant role in parental care is still unclear for this species. Dama ge to the brood is regarded as a major force favouring the evolution of par ental care in harvestman species. This field study provides the first exper imental demonstration that egg-guarding by females affords protection again st egg predation in a harvestman species.