Pushing the boundaries: A new genus and species of Dictyoceratida

Descriptive parameters used to segregate sponges into genera, families and orders must always be subject to re-evaluation. A rare foliose sponge usually found between 20-24m depth on reefs in the central Great Barrier Reef, Australia, has occasioned such reappraisal. The distinct thick, organised sand cortex and surface characters of the oscular and poral faces, the regular, simple primary and secondary fibres and the absence of a tertiary skeleton provide the basis for the diagnosis of a new genus. The lamellate form, brilliant white colouration and regular skeletal arrangement are diagnostic of a new species. A new subfamily, Phyllospongiinae, is established within the Thorectidae, to encompass the new genus and the other foliose dictyoceratid genera Phyllospongia, Carteriospongia, Strepsichordaia and Lendenfeldia. In addition to fibre structure, chemotaxonomic characters and choanocyte chamber morphology support the establishment of the new subfamily. Members of the Phyllospongiinae contain homoscalaranes and a unique series of bishomoscalaranes. While the structure of the new sponge has precipitated a subfamilial rearrangement within the Thorectidae, the task of assigning species and genera to other thorectid subfamilies is not complete at this time.