Xenoturbella

Xenoturbella is a genus of bilaterian animals; it contains a small number of marine worm-like species. The first known species (Xenoturbella bocki) was discovered in 1915 by Sixten Bock but the first published description was only in 1949 by Einar Westblad.

Taxonomy

The genus Xenoturbella contains the species

In 2016, four new species were described:

The smaller (up to 4 centimetres (1.6 in) long), shallower water (less than 650 metres (2,130 ft) deep) species, X. bocki and X. hollandorum (with X. westbladi considered a junior synonym of X. bocki), are in a separate clade from the other three larger (10 centimetres (3.9 in) or greater long), deeper dwelling (1,700–3,700 metres (5,600–12,100 ft)) species, with X. churro and X. profunda being sister species within the latter. Rouse and colleagues also argue that X. bocki and X. westbladi are the same species.