Discovery rate of Caenorhabditis species. The number of Caenorhabditis species is plotted cumulatively by year of description or discovery (if known). As of 2010, there were 38 Caenorhabditis species; this is a maximum number, since 6 of the 20 described species are not very well known and are potentially synonymous with other species . The 16 species reported in this study were discovered between 2005 and 2010. The rate of discovery has increased since sampling efforts have focused on rotting fruit and other decaying plant material. The shape of this curve suggests that only a fraction of Caenorhabditis species is presently known.
Kiontke et al. BMC Evolutionary Biology 2011 11:339 doi:10.1186/1471-2148-11-339