WILSON, N.G.*; HALANYCH, K.M.; Auburn University, AL: Underestimates of Antarctica�s biodiversity: phylogeography of the Antarctic crinoid Promachocrinus kerguelensis

Antarctica�s geographical and thermal isolation has led to high levels of endemic species. Although groups such as the pycnogonids and serolid crustaceans are well-known to have undergone major radiations in the Antarctic, the majority of other invertebrate groups are thought to have low numbers of representative species, although these are often endemic to the region. The Antarctic featherstar, or crinoid, Promachocrinus kerguelensis is such an example, with comprehensive morphological work recognising only one valid species, circum-Antarctic in distribution. The use of molecular data has refined our ability to detect cryptic species (although the definition of species will always remain somewhat arbitrary); we can now easily detect clades with different evolutionary trajectories. If Promachocrinus kerguelensis is indeed a single, widespread species, we might also expect to see the influence of the Antarctic circum-polar current on the directionality of gene flow. Here we investigate the genetic diversity in populations of a widespread, monotypic species of crinoid. Promachocrinus kerguelensis shows distinct genetic structure and subdivision, consistent with a radiation of multiple species. We suggest that this unrecognised pattern may be also present in other circum-Antarctic species, thus obscuring the real diversity occurring in Antarctica.