Suggested nemertean interrelationships. (A) Traditional nemertean phylogeny based on adult morphology, modified after . The phylum is divided into two sub-taxa: Anopla and Enopla. Anopla comprises Palaeonemertea and Heteronemertea. Enopla comprises Hoplonemertea and Bdellonemertea. (B) Nemertean interrelationships based on EST data, modified after . “Palaeonemertea” is a paraphyletic assemblage where only some of its representatives constitute a basal offshoot within Nemertea. The Pilidiophora contain the Heteronemertea and the Hubrechtidae and form a monophyletic clade whose members develop via a pilidium larva. The sistergroup to the Pilidiophora is the monophyletic Hoplonemertea. The Hoplonemertea, which in this phylogeny are a synonym for Enopla, include Bdellonemertea. Similar to the “Palaeonemertea”, its representatives develop via a planuliform larva.