Two species of dictyostelid cellular slime molds from Alaska

In sampling soils to survey dictyostelid cellular slime molds in Alaska we encountered two groups of isolates that have morphologies that differ from any previously described species within their group. We sequenced the nuclear small subunit ribosomal RNA gene (SSU rDNA) of selected isolates from the two groups and found sequences from both groups to be distinct from all previously described dictyostelid sequences. Phylogenetic analyses place one novel species in dictyostelid Group 2 and the other in Group 4 (Schaap et al. 2006 Schaap P, Winckler T, Nelson M, Álvarez-Curto E, Elgie B, Hagiwara H, Cavender JC, Milano-Curto A, Rozen DE, Dingermann T, Mutzel R, Baldauf SL. 2006. Molecular phylogeny and evolution of morphology in the social amoebas. Science 314:661–663. [Google Scholar]). In this paper we formally describe as new these two species of cellular slime molds, Dictyostelium ammophilum sp. nov. and Dictyostelium boreale sp. nov., based on the combination of morphological and molecular characters.