CAMPBELL, T.G.*; GAREY, J.R.; University of South Florida: Phylogenetic Analysis of the Micrognathozoan, Limnognathia maerski, Based on the 18S rRNA Gene

Micrognathozoans were first discovered in 1994 by Reinhardt Kristensen and Peter Funch after an analysis of the meiofauna of a cold freshwater spring on Disko Island, Greenland. The only described micrognathozoan species, Limnognathia maerski, is a small, soft-bodied animal with scleroterized jaws similar to those found in members of Gnathifera (= Rotifera and Gnathostomulida). Some studies have suggested that Micrognathozoa is the sister group to Rotifera, whereas others have implied stronger affinities with Gnathostomulida. Most analyses have agreed, however, that the morphological characteristics of L. maerski are distinct enough to allow the description of a new phylum, Micrognathozoa. Until now, no DNA sequences have been available for phylogenetic analysis of this species. We have sequenced an approximately 1100 base-pair region of the 18S rRNA gene for L. maerski and have performed phylogenetic analyses to determine its position within Gnathifera. These analyses have placed L. maerski as a sister group to Gnathostomulida. Analyses of 18S rRNA gene sequences of the gut contents of L. maerski have allowed the determination of some of the feeding behavior of this organism. From the sample we obtained, an approximately 1800 base-pair region of the 18S rRNA gene was amplified by PCR for the gut contents of the animals. The sequencing of this region and the comparison to other 18S rRNA gene sequences have revealed a single plant species from the family Ranunculacea.