Analysis of Taxonomic Congruence Among Morphological, Ecological, and Biogeographic Data Sets for the Leptopodomorpha (Hemiptera)

Abstract

A data set of 47 morphological characters derived from the literature and original observation is prepared for the Leptopodomorpha. An argument is presented for considering the Leptopodomorpha as a monophyletic group and the Nepomorpha as its sister group. The data set is analyzed by cladistic (Wagner) and phenetic (UPGMA) methods in an effort to arrive at a most natural classification. Predictivity and stability are measured by comparing classifications based on a complete and partial taxon set as well as a random bipartition of the character set. Cladistic analysis produces more stable and predictive classifications with greater consensus and component information. The minimum length Wagner tree has greater information content than the UPGMA phenogram by virtue of its higher cophenetic correlation coefficient and its more parsimonious description of the character data. The Wagner tree is compared with 4 existing classifications for the Leptopodomorpha in the form of networks and trees. One of the published schemes is represented by the same network as the most parsimonious tree, but contains additional homoplasies as a rooted tree. The remaining published schemes are represented by different networks and describe the data less accurately (in more steps) than the most parsimonious tree. Wagner, UPGMA, and published results are examined for congruence with available ecological and distributional data. The minimum length Wagner tree and a published scheme of Polhemus show maximum congruence. A classification isomorphic with the Wagner tree is proposed as the one which should be used for future studies in the Leptopodomorpha. Objective criteria for evaluating classifications and properties of cladistic and phenetic methods are discussed.