A numerical taxonomy of Orthopteroid insects

Abstract

Two numerical taxonomic methods, including one that incorporates phylogenetic ideas and one which has a strictly phenetic approach, were applied to the evaluation of the affinities of the orthopteroid orders of insects. These methods were adapted to the special problems which arise when higher taxa are being compared. A total of 92 characters covering most of the internal and external anatomy served as the basis for the calculations, which indicated that similar diagrams of affinities were obtained, whether or not phylogenetic ideas were incorporated into the analysis. The stability of the pattern of affinities was such that repeating the analysis with a random sample of 30 characters instead of the full set of 92 entrained only trivial differences. Although the characters used in this study were qualitative, the extent to which existing multi- variate theory can be used in evaluating the results is stressed. Australian orthopteroids were mainly used for this experiment. A close relationship between the Australian Morabinae and the South American Proscopiidae was found. This group seems to have split off at an early stage from the stem of the Caelifera, which is distinct from the stem bearing the Ensifera. Another fairly close relationship revealed was that between the Phasmatodea and the Dermaptera. Attempts to reveal inconsistencies in the currently accepted taxonomic groupings suggested that the distinction between blattids and mantids within the Dictyoptera is of less than subordinal rank. The essential homogeneity of the orthopteroid orders is shown by the fact that even the most disparate groups share almost half the 92 characters.