The Scalidophora is a clade that includes the traditional phyla Priapula, Kinorhyncha, and Loricifera. This grouping has been recovered as monophyletic in a diversity of studies (Halanych 2004). Nielsen (2001) used the name Cephalorhyncha for this clade, but (as Nielsen himself noted) this name has been used previously for a clade that also included the Nematomorpha. Based on new molecular data and analyses, Sørensen et al. (2008) concluded that the Loricifera and Nematomorpha appear to be sister taxa, which would make the Scalidophora (or Cephalorhyncha sensu Nielsen 2001) clade paraphyletic. As of 2010, relationships among phyla within the Ecdysozoa remain poorly resolved, so it is difficult to know which groups will eventually win wide acceptance by specialists as convincingly monophyletic and deserving of a name.
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