New data from an enigmatic phylum: evidence from molecular sequence data supports a sister-group relationship between Loricifera and Nematomorpha

• Published in: Journal of zoological systematics and evolutionary research Vol. 46; no. 3; pp. 231 - 239
• Main Authors: Sørensen, M.V, Hebsgaard, M.B, Heiner, I, Glenner, H, Willerslev, E, Kristensen, R.M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.08.2008; Blackwell Publishing Ltd; Hindawi Limited
• Subjects: Centroderes; Cycloneuralia; Ecdysozoa; Echinoderes; evolution; Kinorhyncha; Loricifera; Marine; Nanaloricus; Nematomorpha; phylogeny; Priapulida; Priapulopsis; progenesis; Pycnophyes; Scalidophora; Tubiluchus
• ISSN: 0947-5745; 1439-0469
• DOI: 10.1111/j.1439-0469.2008.00478.x

Loricifera is one of the most recently discovered animal phyla. So far, the group has been considered closely related to Kinorhyncha and Priapulida, and assigned to the ecdysozoan clade Cycloneuralia. Using Bayesian inference, we present the first phylogeny that includes 18S rRNA and Histone 3 sequences from two species of Loricifera. Intriguingly, we find support for a sister-group relationship between Loricifera and Nematomorpha. Such relationship has not been suggested previously and the results imply that a revision of our conception of early ecdysozoan evolution is required. Additionally, the data suggest that evolution through progenesis (sexual maturation of larvae) may have played an important role among the ancestral cycloneuralians.