ECOLOGICAL-STUDIES ON AECHMEA-BRACTEATA (SWARTZ) (BROMELIACEAE)

In the Yucatan peninsula, Mexico, Aechmea bracteata is more frequent i n the low inundated forest than in hummocks or the semi-evergreen fore st. Due to its flat smooth, ovoid seeds disseminated by birds, this ep iphyte generally develops on rough-barked trees at the point where a l arge branch forks out. The presence of a rhizome permits the formation of groups of ramets comprising different levels of development from y oung shoots to blossoms and the differential rotting of dead dry ramet s. In green mature ramets, an amphora-shaped leaf develops around the inflorescence, delimiting a central watertight cavity. Around this cen tral cavity, inter-leaf spaces correspond to peripheral cavities where rainwater may accumulate. This structure permits the plant to be both a phytotelm and a myrmecophytic epiphyte, with green ramets shelterin g a large diversity of both aquatic (mostly Diptera larvae) and terres trial animals (mostly ants, cockroaches, mites, and springtails). Conc erning ants, peripheral cavities sheltered small Myrmicinae (31.3% of the ramets), central cavities Pachycondyla villosa (Ponerinae) or Doli choderus bispinosus (Dolichoderinae) (91.9%; N=248). Rotting dry ramet s sheltered only terrestrial animals, mostly detritivores which are cl assically present in the leaf litter and ants such as Cyphomyrmex minu tus, a primitive Attini and numerous Ponerinae, predators of the detri tivores. Both green and dry ramets constituted good shelters for incip ient colonies.