Biodiversity in Southeast Asia: an overview of freshwater sponges (Porifera:Demospongiae:Spongillina)

Despite the fact that South East (SE) Asia is considered as a biodiversity hotspot, knowledge of sessile invertebrates such as
freshwater sponges (Porifera: Haplosclerida: Spongillina) in this region is poor and scarcely reported. For this synopsis, diversity
and distribution of SE Asian inland water sponges is reported on the basis of available literature and a recent biodiversity assessment
of the Lower Mekong basin. A diagnostic key of families/genera from SE Asia is provided together with Light Microscopy and Scanning
Electron Microscopy protocols to prepare the basic spicular complement for taxonomic identification. So far, SE Asian freshwater
sponges consist of widespread and/or endemic species belonging to the families Metaniidae, Potamolepidae, and Spongillidae. The
highest diversity is recorded from Indonesia, Philippines, Thailand, and Myanmar, respectively. Data from the other countries are
necessary for our understanding of their diversity and distribution. Biodiversity in SE Asia is strongly underestimated, as indicated
by recent new records and the discovery of new species of freshwater sponges in Thailand. Further investigations should reveal
higher values of taxonomic richness, highlighting biogeographic patterns at the family/genus/species levels. A cooperative network
involving Thai, Laotian and Italian researchers, was set up to contribute and fulfil knowledge on taxonomy, ecology and biotechnological
potentialities of these neglected filter feeders, playing a key role in water purification and biomass production in both lentic
and lotic ecosystems in the tropics.