Cryptic Species Among Sound-Producing Ensiferan Orthoptera (Gryllidae and Tettigoniidae)

Abstract

Studies of calling songs and seasonal life histories of crickets and long-horned grasshoppers have revealed many species that were unrecognized on the basis of morphological studies. Once recognized, such cryptic species usually prove to have identifying morphological characters. Nearly one-fourth of the ensiferan species of eastern United States are cryptic, and high proportions of cryptic species have been found in other groups that have conspicuous, non-morphological, species recognition signals or that have been intensively studied. Similarly high proportions of cryptic species must exist in many groups which have not been intensively studied and in which cryptic species are difficult to detect. The existence of cryptic species demonstrates the lack of correlation between reproductive isolation and degree of morphological differentiation. Therefore the taxonomic treatment of morphologically similar, allopatric or allochronic populations must remain subjective and arbitrary until we have reliable criteria for predicting the evolutionary consequences of such populations becoming sympatric and synchronic.