| Earthworms are very important soil inhabitants which have beneficial influences on soil structure, composition, and properties 1-3. Diplocardia is the native North American earthworm genus with the greatest number of species, widely distributed through the southern states of the USA4,5. Despite this fact, this genus has received little to no attention in phylogenetics, nor has a genetic library been developed for it. Currently, the most reliable method for identification of Diplocardia species is through tedious microscopic dissections. This method requires adequate training and experience, and it is not able to delimit juvenile Diplocardia and specimens with immature sexual features. Also, the procedure requires tedious exploration of the internal morphology under light microscope. Because the number of distinctive features is small, and they are highly variable, the morphological method of delimiting of Diplocardia is not always consistent or reliable. Since molecular markers potentially can provide more reliable characters for distinguishing taxa, they may provide an easier and more reliable Diplocardia species determination.;This research is focused on resolving the phylogenetic relationships among the species of the genus Diplocardia, using sequences of 16S ribosomal DNA (∼500 bp) and cytochrome c oxidase subunit I (C41) (∼706 bp). Sequence data from 16S rDNA was analyzed separately and in combination with morphological characters (33 total for each specimen). Distance based (neighbor joining) and character based (Bayesian) approaches were used to resolve the phylogenetic relationships among Diplocardia species. |
