Relative environmental simplicity in the McMurdo Dry Valleys provides an ideal environment for furthering studies of the relationship between biodiversity and ecosystem functioning. Establishing species richness in the Dry Valleys is key to drawing conclusions about this relationship. Antarctic nematode diversity is generally considered to include five main species, only one of which belongs to the genus Eudorylaimus. However, preliminary data suggests the existence of multiple Eudorylaimus species. Phylogenetic analysis of Antarctic Eudorylaimus was carried out using 28s rDNA, yielding evidence for the existence of at least three distinct species. Further molecular analysis will be carried out, including analysis of the 18s and ITS regions. Also, concordance between molecular and morphological data will be examined to provide further evidence for the presence of more than one species of Eudorylaimus in the Antarctic Dry Valleys. Factors that influence speciation of Eudorylaimus in the Dry Valleys will be discussed.