Island gigantism or dwarfism?

The giant pill-millipedes reaching the size of a baseball belong to Madagascar's most conspicuous invertebrates. Especially members of the genus Sphaeromimus (Latin for 'small ball') possess highly developed stridulation organs in both the male (the 'harp') and the female (the 'washboard') sex. Recent molecular and morphological phylogenies show that the members of this genus are closer related to pill millipedes from India than to other species from Madagascar. Nevertheless, they are poorly known. Recent inventory programs already lead to the discovery and description of one new genus and 36 new species. Now, around six new species of the genus Sphaeromimus were discovered, including one spectacular species which seems to display island gigantism (reaching a size larger than a golf ball). The aim of this study is to find out, if this gigantism is a recent development or an old trait inside the endemic genus Sphaeromimus.

Research methods and techniques:
REU participants in this project will receive training in general millipede morphology, and will handle and sort specimens from our and other museums' collections, image important morphological characters using light and scanning electron microscopy, collect data on the morphological differences of various species, as well as prepare descriptions of these species.

Curator/Advisors: Dr. Petra Sierwald, Zoology/Arachnida & Myriapoda, in collaboration with postdoctoral fellow Dr. Thomas Wesener