Phylogenetic Relationships and Taxonomic Position of the Ribbon Worms of the Genus (Nemertea, Palaeonemertea) with Descriptions of Two New Species.

The genus Gibson and Sundberg, 1999 was first described within the family Hubrechtiidae (class Pilidiophora) and subsequently transferred to the family Callineridae (class Palaeonemertea). Here we describe two new species, sp. nov. from the Sea of Japan (Russia) and sp. nov. from the South China Sea (China). A phylogenetic analysis based on partial sequences of five nuclear and mitochondrial gene regions, rRNA, rRNA, histone H3, rRNA, and , has confirmed the monophyly of the genus , and indicated a close relationship to Bergendal, 1900, whose monophyly is not confirmed. Both genera belong to the family Tubulanidae, with its junior synonym being Callineridae. Three major subclades are distinguished within the Tubulanidae: subclade s. str., subclade , and subclade + . The further status of depends on whether the paraphyly of is confirmed or not and how the problem of paraphyly of the genus Renier, 1804 is resolved.