Sur l'association de Phoronis australis (Phoronida) avec Cerianthus maua (Ceriantharia) dans les zones récifales de Madagascar

The occurrence of Phoronis australis Haswell in the tubewalls of Cerianthus maua Carlgren at Madagascar allows us to describe the taxonomic characteristics of both species and to deal with ecological aspects of the bottoms colonized. The tube wall of C. maua may be divided into 5 distinct layers. P. australis builds his own tube (whose position in the cerianthid-tube is studied): the ampulla always occurs in the fourth layer, and the lophophore projects externally. The Phoronis australis-Cerianthus maua association can be defined as an inquilinism on the basis of three relations: substrate, feeding, protection (C. maua probably obtains no advantage from this association).