Abstract. 1. The macrofauna living inside the phytotelmata or on the foliage of bromeliads could be directly affected by habitat and seasonality. Habitat may also have indirect effects by affecting plant morphology.
2. In Chaco forests, a facultative epiphytic bromeliad (Aechmea distichantha) shows different morphology when growing in sun and shade conditions. Therefore, the abundance and assemblage composition of the macrofauna living on this bromeliad were analysed in different habitats and seasons.
3. Sun plants were shorter, had higher tank water content, but lower litter mass than shade ones. Phytotelmata water temperature and pH were similar between habitats.
4. In the phytotelmata, the macrofauna abundance and richness per plant, as well as total richness, were similar between habitats and among seasons. Detritivores were more abundant than predators in all habitats and seasons. Shade plants had a higher proportion of detritivores than sun plants in spring and summer, but not in winter.
5. On the bromeliad foliage, the macrofauna abundance and richness per plant were lower in winter. There were no differences in abundance between habitats, but shade plants had higher species richness than sun plants. In spring and summer, total richness was higher in shade plants than in sun plants. In spring and summer, detritivores were more abundant for shade, whereas ants were more abundant in sun plants. The proportion of hunting spiders was higher in the shade in spring and summer.
6. Our study showed that habitat mainly affects bromeliad-foliage macrofauna, but not the phytotelmata macrofauna.