On the presence of anatriaenes in Pachastrellidae (Porifera: Demospongiae): Evidence for a new phylogenetic family concept

Species bearing long-shafted triaenes do not fit the traditional diagnosis of the family Pachastrellidae. However, the present study confirmed the occurrence of anatriaenes in Characella tripodaria (= Sphinctrella linaresi and Poecillastra rudiastra, n. syn.) and Poecillastra armata. Although anatriaenes were also formerly described in some specimens of Characella pachastrelloides, the results of our re-examination suggest that these spicules are not proper of this species, but foreign material incorporated from the sediment. Because of the presence of anatriaenes in C. tripodaria and P. rudiastra, the generic diagnoses of Poecillastra and Characella have been amended. Apart from the taxonomic interest, the present finding requires us to reconsider the possibility that the presence of anatriaenes is ancestral in the Pachastrellidae. Under such an assumption, Pachastrellidae can no longer be considered as a primitive astrophorid family and its calthrops-pseudocalthrops should be regarded as a type of reduced triaenes.