''Eudistoma'' is a genus of

sea squirts Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class (biology), class in the subphylum Tunicate, Tunicata of sac-like marine (ocean), marine invertebrate filter feeders. Ascidians ar ...

belonging to the class

Ascidiacea Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" ...

. It was first described in 1909 by Maurice Caullery. Originally it was thought to be a subgenus of '' Distoma''. ''Eudistoma'' is the most species-rich genus in the family Polycitordae, with 124 valid species as of 2014. They are found in tropical and temperate waters; some species are also found in the Antarctic and subtropical area.

Description

In 1909 Caullery described ''Eudistoma'' as a subgenus of ''Distoma'' due to the rows of stigmata in the

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...

. In 1917 Ritter and Forsyth described it as a separate genus without explanation. Three subsequent papers published in 1919, 1921 and 1942 all considered it to be a subgenus of ''

Polycitor ''Polycitor'' is a genus of tunicates belonging to the family Polycitoridae. The genus has almost cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of ...

''. ''Eudistoma'' was finally considered a valid genus in 1945 due to "the three rows of

pharyngeal slits Pharyngeal slits are filter-feeding organs found among deuterostomes. Pharyngeal slits are repeated openings that appear along the pharynx caudal to the mouth. With this position, they allow for the movement of water in the mouth and out the phary ...

, long esophagus, flat stomach in the posterior region of the abdomen, very conspicuous longitudinal muscles extending from the pharynx to the end of the abdomen and larvae that are incubated in the atrial cavity." Identification of species within the genus has been difficult at times due to the wide variety in shape and colour.

Medical research

Biologically active

alkaloids Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar st ...

have been isolated from a number of species of ''Eudistoma'', some of which have been studied for their

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

properties. A number of these substances have been grouped under the name

eudistomin Eudistomins Eudistomins are β-carboline derivatives, isolated from ascidians (marine tunicates of the family ''Ascidiacea''), like ''Ritterella sigillinoides'', ''Lissoclinum fragile'', or ''Pseudodistoma aureum''. Types of Eudistomin Eudis ...

, though they are not only found in ''Eudistoma'' species. They are being investigated for their possible use as antibiotics and anti-cancer agents. Pibocin B is an

alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

isolated from an ascidian in the genus ''Eudistoma''.

References

{{Taxonbar, from=Q4912362 Enterogona Tunicate genera