Geometric approaches to the taxonomic analysis of centipede gonopods (Chilopoda: Scutigeromorpha)

Abstract

The female gonopods of the Scutigeromorpha have traditionally played an important taxonomic role but to date have only been compared using simple indices and general shape descriptions. Extended eigenshape analysis and relative warps analysis were used to evaluate the taxonomic information content of these structures. Gonopod shapes of five species including members of Scutigera, Sphendononema, Thereuonema, Thereuopoda, and Thereuopodina, and three eastern Australian species of Allothereua were characterized using a combination of landmark and semi-landmark-based sampling protocols. Cross-tabulation of canonical variates ordination in the extended eigenshape and relative warps shape spaces, using a centroid-proximity distance metric, resulted in a high proportion of specimens being correctly assigned to genus, species, and subspecies groups. These results indicate that substantial and consistent gonopod shape differences between taxa occur at each of these levels. Comparison of the eigenshape and relative warps results also suggests that a combined landmark-semi-landmark sampling approach best captures the taxonomically relevant aspects of gonopod shape variation. © 2009 Natural History Museum, London.