''Eudistoma'' is a genus of

sea squirt Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer test or "tunic" made of the polysaccharid ...

s belonging to the family

Polycitoridae Polycitoridae is a family of tunicates belonging to the order Aplousobranchia. Genera: * '' Archidistoma'' Garstang, 1891 * '' Brevicollus'' Kott, 1990 * '' Cystodytes'' Drasche, 1884 * '' Eucoelium'' Savigny, 1816 * '' Eudistoma'' Caullery, 190 ...

. It was first described in 1909 by

Maurice Caullery Maurice Jules Gaston Corneille Caullery (5 September 1868, Bergues – 13 July 1958, Paris) was a French biologist. Biography He was born in Bergues in north France on 5 September 1868. His early education was in Douai. He began as a lectu ...

. Originally it was thought to be a subgenus of ''Distoma''. ''Eudistoma'' is the most species-rich genus in the family

, 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 (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

. In 1917

Ritter Ritter (German for "knight") is a designation used as a title of nobility in German-speaking areas. Traditionally it denotes the second-lowest rank within the nobility, standing above " Edler" and below "" (Baron). As with most titles and desig ...

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''. ''Eudistoma'' was finally considered a valid genus in 1945 due to "the three rows of pharyngeal slits, 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 broad class of naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large variety of organisms i ...

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 toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...

properties. A number of these substances have been grouped under the name eudistomin, 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, also known as 1-methoxy-2-bromo-6,8β-dimethylergoline, is an

ergoline Ergoline is a core structure in many alkaloids and their synthetic derivatives. Ergoline alkaloids were first characterized in ergot. Some of these are implicated in the condition of ergotism, which can take a convulsive form or a gangrenous for ...

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

isolated from an

ascidian Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer test or "tunic" made of the polysaccharid ...

(sea squirt) in the genus ''Eudistoma''.

References

{{Taxonbar, from=Q4912362 Aplousobranchia Tunicate genera