Geometric morphometrics, the metendosternite and its use in phylogenetics of the Scarabaeinae (Coleoptera)

Results from a geometric morphometric and cladistic analysis of 20 species (including 4 flightless species) of the Scarabaeinae (Scarabaeidae: Coleoptera) were compared. The metendosternite has largely been neglected in past morphological studies but proved to be very useful because of its easily identifiable landmarks. These landmarks were analyzed in a geometric morphometric analysis, where a Procrustes distance matrix and a dendrogram were produced. A relative warp analysis was also performed on the data and the results of the first two relative warps plotted against one another. The dendrogram clearly distinguished the flightless species from the flighted and it is hypothesized that three lineages of flightless taxa convergently underwent similar alterations in the reduction in metendosternite size. The cladistics study utilized 200 internal and external morphological characters, including 20 based on the metendosternite. Comparison of the cladogram with the dendrogram indicates that geometric morphometrics is a useful technique to hypothesize relationships, especially with structures that may be difficult to interpret in a cladistic analysis.