Predicting species richness for Australasian freshwater macroinvertebrates: do we want to know?

Predicting species richness for Australasian fresh- water macroin vertebrates: do we want to know?Memoirs of the Museum ol Victoria 56(2): 483-490.The identification of freshwater macroinvertebrates to family level is becoming increas- ingly popular for surveys, predictive models and pollution indices in Australia because it is quicker and cheaper than genus or species level identification, and it requires less specialised knowledge.Family richness has been used as a predictor of species richness for other taxo- nomic groups such as vertebrates, ants and plants and we were interested in seeing whether this might be a useful method for freshwater macroinvertebrates.Taxon lists from one Papua New Guinean and 34 Australian datasets from lentic and lotic waters were used to regress the number of families against the total number of taxa (species where possible).Also, the ability of the number of species and morphospecies within some orders (Coleop- tera, Diptera, Ephemeroptera and Trichoptera) to predict overall species richness was investigated.The number of all families explained 91% of the variation in species richness.The number of species within each of the orders explained between 60 and 85% of the variation in overall species richness.We conclude that it would be possible to predict species richness in this way, particularly if sampling techniques and sampling effort were standard- ised.The terms 'species richness' and 'biodiversity' are often used synonymously although the former is only a subset of the latter.Some of the limitations and dangers of assessing species richness instead of biodiversity are discussed.