Based on very simillar or identical morphological characteristiscs, species that appear to be the same are actually separate species that do not breed. They may be distinguished by mating patterns, songs, courships displays, and other characteristics (Freeman & Herron, 2007). Genetic studies can determine these species to be distinct.
Freeman, S. & Herron, J. (2007). Evolutionary Analysis 4th Ed. Speciation, pp 605 - 633.
Video Reference: American Museum of Natural History. (2012, June 28). Science bulletins: New frog species hiding in plain sight. Retrieved from http://www.youtube.com/watch?v=5uhKnNBNZNw
Cryptic Speciation in Catepillars
Scheffers, B. R., Joppa, L. N., Pimm, S. L., & Laurance, W. F. (2012, September). Review: What we know and don’t know about Earth's missing biodiversity. Trends in Ecology & Evolution, 27(9), 501–510.
Paul D. N. Hebert, P. D. N., Erin H. Penton, E. H., Burns, J. M., Janzen, D. H., & Hallwachs, W. (2004). Ten species in one: DNA barcoding reveals cryptic species in the Neotropical skipper butterflyAstraptes fulgerator. Proceedings of the National Academy of Science of the United States of America, 101(41), 14812–14817.
Learn more about Amazonian cryptic frog species....
Amazonian species Engystomops and Hypsiboas, were discovered to consist of 5-7, and 6-9 cryptic species; species richness has been underestimated in the Amazon, and recent studies are finding even more cryptic species (Funk, Caminer, & Ron, 2012).
Funk, W. C., Caminer, M., & Ron, S. R. (2012, May). High levels of cryptic species diversity uncovered in Amazonian frogs. Proceedings of the Royal Society B, 279(1734), 1806-1814. doi: 10.1098/rspb.2011.1653. Retrieved from http://rspb.royalsocietypublishing.org.proxy.lib.muohio.edu/content/279/1734/1806.full