Bioeroding sponges common to the Central Australian Great Barrier Reef: Descriptions of three new species, two new records, and additions to two previously described species

A large collection of bioeroding sponges was obtained from the following reefs of the Central Great Barrier Reef (GBR), Australia: Myrmidon, John Brewer, Rib and Pandora Reefs, and Pelorus, Orpheus, Fantome, Great Palm, Acheron and Magnetic Islands. As many descriptive characters as possible were used including skeleton and tissue characters, but also field observations in situ and bioerosion traces. Bioerosion traces are very similar between species; nevertheless, they yield extra information on genus level. The following sponges are described in detail: Cliona tinctoria sp. nov., Cliona orientalis, new record for the GBR, Pione caesia sp. nov., incertae sedis, Cliothosa hancocki, new record for the GBR, Zyzzya criceta sp. nov. Descriptions of selected characters of two previously described GBR bioeroding sponges, Cliona celata and Aka mucosa, are amended. C. orientalis belongs into a species group previously named as 'Cliona viridis complex', species of which are difficult to discern from each other. C. orientalis can be recognized by its spiraster morphology, i.e. by their multisplit actines along the convex side of a spiraling spiraster shaft. Summarizing tables with descriptive characters for all described species and for species of the 'Cliona viridis complex' are given.