Biogeography and phylogeny of Chondrilla species (Demospongiae) in Australia

Abstract

The biogeography and phylogeny of Chondrilla (Porifera, Demospongiae) species in Australia is poorly understood. Until the present study was carried out, 4 Chondrilla species were thought to occur in the waters of Australia and its territories: C. australiensis, C. secunda, C. mixta and C. nucula. However, the type specimen of the latter comes from the Adriatic Sea, and it has always been uncertain whether this species is present in Australia. The difficulty in determining the number of species of Chondrilla and their biogeography is largely due to the paucity of phenotypic characters that are normally used for identification. To clarify the diversity and distribution of sponges in this genus in Australia, DNA sequence analysis was applied to samples of Chondrilla from around Australia and compared to C. nucula from the Mediterranean. Classical taxonomic techniques were used to confirm the molecular results. Evidence was found for 3 species of Chondrilla in the temperate southern oceans of Australia with one, C. australiensis, also extending into tropical waters. All 3 species were distinct from C. nucula, which was not found in Australian waters in this study. The distribution of C. australiensis suggests that larvae and/or fragments of this sponge are able to disperse across very large distances around the coastline of Australia. Species identification based on direct sequencing of the D2 region in the 28S rDNA and ITS1-5.8S-ITS2 region was in agreement with results using classical taxonomic techniques.