A new species ofTriptolemma(Porifera: Pachastrellidae) from the Pacific Ocean with a revision of the genus

Abstract

A new species,T. strongylatasp. nov. is described on the basis of material collected from the Pacific Ocean. The new species is characterized by the presence of sinuous strongyles. Moreover the incomplete description ofT. simplex(Sarà, 1959) is implemented on the basis of new abundant material allowing, for the first time, the complete description of the skeleton of aTriptolemmaspecies and the detecting of the presence of monaxonic spicules in the spicular complement of the genus. The skeleton is composed of a thick crust of disorderly arranged mesotriaenes and scattered microscleres, supported by diverging spicule tracts formed by oxeas towards the surface. Both species were recorded associated to boring sponges(SpiroxyaandCliona)in excavations of the calcareous scleraxis of precious corals or in organogenic concretions. In the cavities where the tissue ofTriptolemmawas recorded the wall of the excavation partially lost its typical pattern characterized by ovoid scars and became irregularly eroded. Our hypothesis is thatTriptolemmainsinuates inside the erosions produced by other sponges and it is able to enlarge them by an etching mechanism based on chemical dissolution only.