Ontogenetic trajectories in Symphypleona (Collembola)

A novel approach is proposed toward quantifying changes in chaetotaxy during the development of Collembola Symphypleona. The ontogenetic trajectories method applied to the tibiotarsal chaetotaxy of Symphypleona provides a representation of their development. Every seta, through the probability of its presence, can be regarded as a character. The statistical technique of correspondence analysis is used, and new techniques for analyzing these kinds of data are discussed. Although this survey is mainly focused on methodology, biological results are also presented. The different rates and extent of chaetotaxic changes during development of the species studied are discussed. An important point demonstrated is the support this method gives to the close relationship of Mackenziella and Sminthurididae. The assumption of monophyly of the group Sminthuridae-Bourletiellidae is also reinforced, and a hypothesis of neochaetotic evolution for the genus Sminthurus is put forward. © 1996 Wiley-Liss, Inc.