title: Statistical parsimony networks and species assemblages in Cephalotrichid nemerteans (nemertea).
abstract: BACKGROUND
  It has been suggested that statistical parsimony network analysis could be used to get an indication of species represented in a set of nucleotide data, and the approach has been used to discuss species boundaries in some taxa.
  
  
  RESULTS
  Based on 635 base pairs of the mitochondrial protein-coding gene cytochrome c oxidase I (COI), we analyzed 152 nemertean specimens using statistical parsimony network analysis with the connection probability set to 95%. The analysis revealed 15 distinct networks together with seven singletons. Statistical parsimony yielded three networks supporting the species status of Cephalothrix rufifrons, C. major and C. spiralis as they currently have been delineated by morphological characters and geographical location. Many other networks contained haplotypes from nearby geographical locations. Cladistic structure by maximum likelihood analysis overall supported the network analysis, but indicated a false positive result where subnetworks should have been connected into one network/species. This probably is caused by undersampling of the intraspecific haplotype diversity.
  
  
  CONCLUSIONS
  Statistical parsimony network analysis provides a rapid and useful tool for detecting possible undescribed/cryptic species among cephalotrichid nemerteans based on COI gene. It should be combined with phylogenetic analysis to get indications of false positive results, i.e., subnetworks that would have been connected with more extensive haplotype sampling.
authors.affiliation: Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Chen
authors.forename: Malin
authors.initials: M
authors.lastname: Strand
authors.forename: Jon L
authors.initials: JL
authors.lastname: Norenburg
authors.forename: Shichun
authors.initials: S
authors.lastname: Sun
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kajihara
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Chernyshev
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Maslakova
authors.forename: Per
authors.initials: P
authors.lastname: Sundberg
mesh_terms: D000818:Animals; D056808:Biostatistics / Q000379:methods*; D003576:Electron Transport Complex IV / Q000235:genetics; D056890:Eukaryota / Q000737:chemistry / Q000145:classification* / Q000201:enzymology / Q000235:genetics*; D006239:Haplotypes; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D003576:Electron Transport Complex IV