Xenoturbella hollandorum

Xenoturbella hollandorum
A congeneric species of X. hollandorum ( X. japonica )
Scientific classification
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

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]

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]

References

1. Rouse, Greg W.; Wilson, Nerida G.; Carvajal, Jose I.; Vrijenhoek, Robert C. (2016-02-04). "New deep-sea species of Xenoturbella and the position of Xenacoelomorpha" . Nature. 530 (7588): 94–97. Bibcode:2016Natur.530...94R. doi:10.1038/nature16545. ISSN   0028-0836. PMID   26842060. S2CID   3870574.
2. Khan, Amina (2016-02-05). "Newly discovered deep-sea worms, including one named 'churro,' could shed light on animal evolution". Los Angeles Times. Retrieved 2020-03-10.
3. Morelle, Rebecca (2016-02-03). "Mystery of 'sock of the deep' solved". BBC News. Retrieved 2020-03-10.
4. "We finally know what to make of these 'purple sock' creatures that litter the sea floor". ZME Science. 2016-02-05. Retrieved 2020-03-11.
5. Nakano, Hiroaki (2015). "What is Xenoturbella?". Zoological Letters. 1 (22): 22. doi: 10.1186/s40851-015-0018-z . PMC   4657256 . PMID   26605067.
6. "Around the Pier: Churro-Like Marine Worm Discovered by Scripps Scientists Is One of the 'Top 10 Species of 2017'". Scripps Institution of Oceanography. 2017-05-30. Retrieved 2020-03-10.^{[ permanent dead link ]}
7. Nakano, Hiroaki; Miyazawa, Hideyuki; Maeno, Akiteru; Shiroishi, Toshihiko; Kakui, Keiichi; Koyanagi, Ryo; Kanda, Miyuki; Satoh, Noriyuki; Omori, Akihito; Kohtsuka, Hisanori (2017-12-18). "A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella". BMC Evolutionary Biology. 17 (1): 245. doi: 10.1186/s12862-017-1080-2 . ISSN   1471-2148. PMC   5733810 . PMID   29249199.