Annulonemertes (phylum Nemertea): when segments do not count.
We estimated the phylogenetic position of the pseudosegmented ribbon worm Annulonemertes minusculus to test proposed evolutionary hypotheses to explain these body constrictions. The analysis is based on 18S rDNA sequences and shows that the species belongs to an apomorphic clade of hoplonemertean species. The segmentation has no phylogenetic bearing as previously discussed, but is a derived character probably coupled to the species' interstitial habitat.
Department of Zoology, Göteborg University, PO Box 463, 405 30 Göteborg, Sweden. p.sundberg@zool.gu.se
Per
P
Sundberg
Malin
M
Strand
D000818:Animals; D001499:Bayes Theorem; D007448:Invertebrates / Q000145:classification*; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics
D012337:RNA, Ribosomal, 18S