Well with cryptic species there is usually a hint. A tickle at the back of your brain. Maybe it is a species with wide morphological variation or a complex distribution that makes you wonder whether there are additional species hiding within.
Many cryptic species are uncovered when molecular data is used to examine the relationships between species. Members of a cryptic species may seemingly look the same, but not be each other's closest relatives. And thus the real adventure begins.
Medina, R; Lara, F; Goffinet, B; Garilleti, R; Mazimpaka, V. 2012. Integrative taxonomy successfully resolves the pseudo-cryptic complex of the disjunct epiphytic moss Orthotrichum consimile s.l. (Orthotrichaceae) Taxon 61:1180-1198.
|The star of the show Orthotrichum consimile. Figure 2B from Medina et al. 2012|
I think that this study is a great example of morphological and molecular research complementing each other to address a question of species relationships. With morphologically austere lineages (Bickford et al. 2007), such as bryophytes, the challenge of teasing apart cryptic species may seem daunting. However, this study of Orthotrichum shows that when a systematic and detailed approach is used, uncovering cryptic species is possible even in the morphologically austere mosses.
If you are interested in reading more about Dr. Medina's research or downloading a pdf of this paper check out his page on Academia.edu.
Medina, R, Lara, F, Goffinet, B, Garilleti, R, & Mazimpaka, V (2012). Integrative taxonomy successfully resolves the pseudo-cryptic complex of the disjunct epiphytic moss Orthotrichum consimile s.l. (Orthotrichaceae) Taxon, 61 (6), 1180-1198