Molecular Phylogeny of Some European Heteronemertean (Nemertea) Species and the Monophyletic Status ofRiseriellus, Lineus,andMicrura

Redescription ofLineus acutifronsSouthern, 1913 (Nemertea: Pilidiophora) and comments on its phylogenetic position

“…Pilidiophoran systematics is still obscure: Lineus longissimus, the type species for the genus Lineus, is more closely related to Riseriellus occultus and Ramphogordius sanguineus (Sundberg and Saur 1998;Strand et al 2005;Schwartz 2009) or Lineus viridis (this paper), than with other Lineus species. Our data suggest that L. acutifrons is not a member of the genus Lineus.…”

“…Inadequate description of species is the unresolved problem within nemertean systematics and further confounds the problem of generic placement. Molecular (Sundberg and Saur 1998;Thollesson and Norenburg 2003;Strand et al 2005) and combined molecular and morphological studies (Schwartz 2009) have basically supported the monophyly of the nemertean orders, and the genus Baseodiscus, but have also demonstrated that poorly defined genera, Lineus, Cerebratulus and Micrura, are not monophyletic.…”

“…Gibson 1990;Rogers et al 1993;Wern 1998;Gibson and Sundberg 2002) or justify taxonomic changes on this basis (e.g Gibson 1989;Envall and Norenburg 2001). Differences in character combinations established up to 70 monotypic genera (Table 3), but without any phylogenetic significance (Sundberg 1993;Sundberg and Saur 1998). These character combinations are used widely among pilidiophorans to delineate genera, yet their value as a taxonomic tool is questionable.…”

Genetics do not reflect habitat differences inRiseriellus occultus(Heteronemertea, Nemertea) from Spain and Wales

“…The taxon illustrates a problem with nemertean systematics where there are few phylogenetic generic definitions. It is clearly a paraphyletic group (Sundberg & Saur 1998;Thollesson & Norenburg 2003), and the species delimitations can furthermore be questioned in many cases. As an example of this, both studies showed that there is no clear genetic distinction between Lineus viridis and Lineus ruber as separated by external morphology.…”

The complete mitochondrial genome of Cephalothrix simula (Iwata) (Nemertea: Palaeonemertea)

“…The argument of a coelomate position for nemerteans was supported by ultrastructural similarity between the blood vessels of nemerteans and the coelom of spiralian coelomates (Turbeville and Ruppert, 1985;Turbeville, 1986;Jespersen and Liitzen, 1988). There is an increasing number of studies using molecular information to provide increasingly refined estimates of within-phylum phylogenetic relationships of nemerteans (e.g., Envall and Sundberg, 1998;Sundberg and Saur, 1998;Thollesson and Norenburg, 2003;Sundberg et al, 2003;Strand and Sundberg, 2005;Sundberg and Strand, 2007). Few studies have addressed the position of phylum Nemertea among metazoans.…”