Xenoturbella hollandorum

Xenoturbella hollandorum is a marine, benthic worm-like species that belongs to the genus Xenoturbella. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists.^[2][3][4] The species was described in 2016.^[1]

Xenoturbella hollandorum
A congeneric species of X. hollandorum (X. japonica)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Xenacoelomorpha
Family:	Xenoturbellidae
Genus:	Xenoturbella
Species:	X. hollandorum
Binomial name
Xenoturbella hollandorum Rouse, Wilson, Carvajal & Vrijenhoek, 2016[1]

Longitudinal section of a congeneric species, Xenoturbella bocki

X. hollandorum shares morphological similarities with other species of the genus Xenoturbella, and is known for lacking respiratory, circulatory and an excretory system.^[5]

Description

The etymology of the species name corresponds to a scientific patronym in honor of Linda and Nicholas Holland.^[6]

Xenoturbella hollandorum is 2.5 cm (0.98 in) in length, with a uniform bright pink colouration. The body wall displays several furrows: on the circumference, on the side, and two deep, longitudinal, dorsal ones. The mouth is orientated ventrally, anterior to the ring furrow. The live specimen exhibits an inconspicuous epidermal ventral glandular network.^[1]

Phylogeny

Comparison of mitochondrial DNA and protein sequences showed that the species X. hollandorum is the sister group to X. bocki. In turn, these two species share evolutionary affinities with X. japonica into a clade of 'shallow-water' taxa.^[1][7]

Species-level cladogram of the genus Xenoturbella.

Xenacoelomorpha     Acoelomorpha     Xenoturbella     'Shallow' clade               X. japonica             X. bocki   X. hollandorum   'Deep' clade               X. monstrosa             X. churro   X. profunda

The cladogram has been reconstructed from mitochondrial DNA and protein sequences.[1][7]