Combining DNA sequences and morphology in systematics: testing the validity of the dragonfly species Cordulegaster bilineata

Abstract

Morphological and molecular techniques are rarely combined when answering questions of taxonomic validity. In this study, we combine morphological techniques with DNA sequences to determine the validity of the dragonfly species Cordulegaster bilineata. The two dragonfly species C. bilineata and C. diastatops are very similar in size, body color, and morphological characters, and due to these similarities, the status of C. bilineata as a valid species is in question. In this study we compare morphological measurements of males and internal transcribed spacer 1 (ITS-1) sequences of rDNA between the two taxa. The hamule measurements (where copulation occurs) of males show little difference between the taxa in question, but the anal appendage measurements (where the male first contacts the female) show marked divergence between the two taxa. Cluster analysis with these anal appendage measurements correctly assigns almost all individuals measured into their respective

DNA Taxonomy and the identification of immature insect stages: the true larva ofTauriphila argo(Hagen 1869) (Odonata: Anisoptera: Libellulidae)

“…Different to breading larvae, species assignment by means of sequence variability becomes an estimation process, similar to morphological analyses. Pilgrim et al (2002) used sequence variability of the nuclear ITS I sequence to demonstrate that Cordulegaster bilineata and Cordulegaster diastatops (Odonata: Cordulegastridae) are indeed two separate species. They found that ITS I sequences of these two species differ by a 51 bp long insertion.…”

“…We showed the potential of mt SSU genes in this field but the incorporation of nuclear gene fragments within this tool kit should be a central task. We are currently exploring the suitability of ITS genes for these purposes (compare Pilgrim et al 2002, Wheekers et al 2001. Ribosomal genes as well as ITS genes are among the most promising canditates since generally applicable primers to amplify regions of interest are readily available.…”

“…With molecular characters it becomes possible to increase resolution of taxonomic work by including genotypic information on species differentiation. The application of DNA taxonomy was recently advocated by several authors (Godfray 2002, Hebert et al 2002, Pilgrim et al 2002, Tautz et al 2002, 2003. It is quite obvious that DNA taxonomy will display its major strength in groups of negligible morphological differentiation and economic importance.…”

Evaluation of economically important traits from sixteen parental strains of the silkworm Bombyx mori L (Lepidoptera: Bombycidae)

“…Several studies related to the use of productivity markers (Fragoso et al 2003, Marco Jr et al 2005 and morphological dissimilarity (Aagaard et al 2002, Pilgrim et al 2002, Dujardin & Le Pont 2004, Arruda et al 2007 as indicators of the best strains for breeding.…”

Molecular phylogeny of the Western PalaearcticCordulegastertaxa (Odonata: Anisoptera: Cordulegastridae)

“…Regardless of the controversial placement and/or validity of several species, to date, only the validity of Cordulegaster bilineata has been tested with molecular markers (Pilgrim, Roush & Krane, 2002). With a Holarctic distribution, this genus comprises approximately 30 species.…”