Submitted to: Society of Nematology Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 5, 2006
Publication Date: June 1, 2006
Citation: Carta, L.K., Skantar, A.M., Erbe, E.F. 2006. Low temperature SEM and molecular phylogenetics of three Diploscapter populations [abstract]. Journal of Nematology. 38 (2):266
Two genetically distinguishable soil populations of Diploscapter cf. lycostoma that lack males are described and compared with a population of Diploscapter coronatus. Low temperature SEM observations showed for the first time lateral lip flaps classically known as laciniae with filopodia-like extensions. These appeared to be independently deformable and either contacted the cuticle of other nematodes, stretched inwardly into the stoma opening, or interdigitated with one another. The face views of lateral stoma walls of D. cf. lycostoma populations are centrally incurved relative to D. coronatus, and internal hamuli margins above the stoma have distinct profiles in the two morphospecies. All populations had enlarged tail annules, and sperm within offset spermathecae. Procorpus length, body width/basal bulb width, gonad lengths, and phasmid position on the tail showed slight differences between the two nominal species. Small subunit (SSU) rDNA parsimony and Bayesian phylogenetic trees failed to demonstrate separation of these two Diploscapter species, and their position relative to Caenorhabditis or Oscheius myriophila (Rhabditidae) was not resolved. However Hsp90 trees resolved Diploscapter independently of a highly supported clade of Caenorhabditis and Oscheius. Intron number in this Hsp90 segment varied from one to five, with the first and fourth intron showing some positional homology across taxa. Diploscapter and parasitic Tylenchida had very similar intron positions. The phylogenetic significance of Hsp90 and its chaperone function for cytoskeletal proteins are briefly discussed.