This is a Forum paper in Ecography that intends to demonstrate (and hopefully foster the discussion on) the importance of including the cryptic diversity in ecological, biodiversity and biogeographic studies to avoid biased results.

Cryptic species are frequently ignored in large-scale studies and monitoring programs. However, it is unknown if this could represent a bias extending beyond the number of missed species. 

By analyzing the butterfly fauna of the west Mediterranean (335 species), researchers defined cryptic species based on the current consensus of the scientific community, studied their properties. Our results show that co-occurrence among cryptic species is significantly lower than among congeneric non-cryptic species. Accordingly, albeit the frequency of cryptic species is homogeneously distributed over the study area, their distribution pattern accounts for most beta-diversity turnover over sea (from 50 to 100%). Beta-diversity turnover, a direct measure of the frequency of species replacement from site to site, is recognized as a fundamental parameter in ecology and is widely used to detect biogeographic patterns. 

These findings represent a change of paradigm in showing that cryptic diversity comprises original qualitative aspects in addition to merely quantitative ones. This highlights the importance of differentiating cryptic species for various research fields and opens the door to the study of further potential particularities of cryptic diversity.

Reference article:Vodă, R., Dapporto, L., Dincă, V. and Vila, R. 2014. Cryptic matters: overlooked species generate most butterfly beta-diversity. - Ecography doi: 10.1111/ecog.00762