Polymastiidae (Demospongiae: Hadromerida) with ornamented exotyles: a review of morphological affinities and description of a new genus and three new species
All polymastiid sponges displaying ornamented exotyles are reviewed and their morphological affinities are reconsidered. The study embraces all known species ofProteleia,Sphaerotylus,TrachyteleiaandTylexocladusas well as several species ofPolymastia. A new genus,Koltunia, is established for the Antarctic speciesProteleia burtonibased on the unique shape of distal ornamentations of its giant exotyles and on the absence of a spicule palisade in its cortex, a rare feature among the polymastiids. Three new species ofSphaerotylusare described –S. renoufifrom the British Isles,S. strobilisfrom South Africa andS. tjalfeifrom West Greenland. Transfer of one New Zealand species fromPolymastiatoProteleiaand of one Chilean species fromPolymastiatoSphaerotylusis proposed. The present study provides a background for future integrative phylogenetic analyses based on comprehensive molecular and morphological datasets which should reveal the natural relationships between the polymastiid taxa.