Using scalarane sesterterpenes to examine a sponge taxonomic anomaly.

A parallel study was conducted on two Indo-Pacific foliose sponges. The first specimen contains 3-hydroxy-20,22-dimethyl-20-deoxoscalarin (2), while the second contains 3-oxo-20,22-dimethyl-20-dioxoscalarin 8 (3). The physical properties as well as X-ray results confirming the structure and stereochemical features of these compounds are presented first. The difficulty we encountered in the taxonomic identification of these species is also discussed. One of our specimens is identical to material considered by different taxonomists as either Phyllospongia vermicularis or Dysidea vermicularis. The other is identified as Carteriospongia sp. We outline that the parallel chemistry of these two specimens suggests that they are closely related taxonomically.