The phylogenetic position of the Arthropoda

Abstract

The arthropods have been treated as one group of animals for a long time. Linnaeus called them Insecta both in the 1st and the 10th editions of Systema Naturae (1735, 1758), and although a number of authors from the first half of the 19th century treated crustaceans, arachnids and insects as separate groups under a common heading, the name Arthropoda was not introduced until Siebold (1848). The first phylogenetic classification of the Animal Kingdom was presented by Haeckel (1866), who in his famous book Generelle Morphologie der Organismen drew the first phylogenetic tree and introduced the word ‘monophyletic’ to describe the nature of the 19 phyla he recognized. However, his classification of lower categories was not based on the same principle. This early attempt at creating a phylogenetic classification of the animals was not followed up during the next century, and textbook and handbook classifications have continued to resemble Linnaeus’ ‘pre-evolutionary’ system. Only Ax (1995) and Nielsen (1995) have attempted to create cladistic arrangements of the phyla.