Diversity and distribution within the sea spider genus Pallenopsis (Chelicerata: Pycnogonida) in the Western Antarctic as revealed by mitochondrial DNA

Abstract

Pycnogonids are marine arthropods with cosmopolitan and eurybathic distribution. Of the approximately 1300 pycnogonid species described worldwide, over 260 species occur in the Southern Ocean, and over half of those are endemic to the Antarctic. Morphological data suggest circumpolar distributions for multiple Antarctic species; however, recent molecular inquiries into the genetic structure of Antarctic benthic invertebrate populations have revealed varying patterns of genetic connectivity and, in many cases, radiation of morphologically cryptic species incompatible with the previously hypothesized genetic homogeneity for Southern Ocean invertebrates. To date, little is known about genetic connectivity within Antarctic Pallenopsis species populations, and Pallenopsis phylogeny remains poorly resolved. This study describes genetic structure of Pallenopsis populations of western Antarctic coastal regions, the Scotia Arc, Falkland Islands, and Chilean coast. We present the results of analyses derived from the mitochondrial COI gene that demonstrate patterns of connectivity for these populations. Examination of genetic characters has allowed for the identification of divergent mitochondrial lineages within Pallenopsis and will lead to a description of at least one new species. Future sampling and analyses from other areas of the Antarctic coastline will provide a broader context for the phylogeny of Pallenopsis.