''Onchnesoma'' is one of the two genera that constitute the family

Phascolionidae ''Phascolionidae'' is a family of peanut worms The Sipuncula or Sipunculida (common names sipunculid worms or peanut worms) is a class containing about 162 species of unsegmented marine annelid worms. The name ''Sipuncula'' is from the gen ...

of Phylum Sipuncula, described by Koren and Danielssen established in 1873 as the type species to ''Onchnesoma steenstrupii''.Cutler, Edward B. & Cutler, Norma J (1985): A revision of the genera ''Phascolion'' Théel and ''Onchnesoma'' Koren and Danielssen (Sipuncula). Proceedings of Biological Society of Washington 94(4):809-850Cutler, Edward B. (1994): The Sipuncula: their systematic, biology and evolution. Comstock Publishing Associates of Cornell University. Ithaca, New York. 406p
Google Books
/ref>

Description

The species of this genus are usually small in size (with a trunk of less than 1 cm in length). The introverted is much longer than the trunk. The body wall muscle layers presents continuous. The disc may present oral tentacles (usually less than 10 and about 8 mm. in length) arranged around the mouth, but those tentacles can be reduced in size or completely absent. The retractor muscle system is a highly modified introverted form fused to form a muscle retractor. The anus is located in the distal half of introverted. Gallbladder contractile is rarely observed and if present is without villi. They have a single nephridium.

Species

* ''Onchnesoma intermedium'' Murina, 1976 * ''Onchnesoma magnibathum'' Cutler, 1969Smithsonian National Museum of Natural History. Antarctic Invertebrates: Onchnesoma magnibathum Cutler, 1969 http://invertebrates.si.edu/antiz/taxon_view.cfm?ScreenWidth=1003&ScreenHeight=567&taxon=8585&MODE=taxon * ''Onchnesoma squamatum'' (Koren y Danielssen, 1875)Koren, J. and Danielssen, D.C. (1875): Bidrag de norskr Gephyreens Naturhistorie. Nytt. Magasin for Naturvidenskapene, 21:201-138. * ''Onchnesoma steenstrupii'' Koren y Danielssen, 1875

References

External links

World Register of Marine Species (WoRMS) ''Onchnesoma'' Koren & Danielssen, 1876 AphiaID: 136024

Integrated Taxonomic Information System (ITIS): Onchnesoma Koren and Danielssen, 1875 Taxonomic Serial No.: 154722
{{Taxonbar, from=Q2262515 Sipunculans