Carotenoid patterns in twenty-nine species of sponges in the order Poecilosclerida (Porifera: Demospongiae): a possible tool for chemosystematics

We assessed the utility of separated carotenoid mixtures for sponge systematics. Carotenoids were extracted from 29 species of 22 genera of 6 families for the demosponge order Poecilosclerida. Mixtures were separated (by thinlayer chromatography on silica gel) without chemical modification and after alteration by saponification, reduction or acetylation or a combination thereof. This approach allowed analysis of individual colonies of less than 1 g wet weight. Relationships among taxa were determined through use of Lawson's similarity index and discriminative analysis. Analysis of multiple runs of fractions from one individual of Ophlitaspongia pennata showed the method to be consistent and reliable. Comparison of specimens of species collected at different localities and times showed high correspondence of carotenoid patterns except in those species suspected of representing species complexes. Analysis of members of the family Clathriidae and of relationships within the order Poecilosclerida suggest that fatty acids esterified to carotenoids may be family-specific and of more taxonomic value than carotenoids. The importance of testing for seasonal, geographic and habitat variability in biochemical patterns is stressed. We discuss the significance of these methods to sponge systematics and their use in comparative studies.