''Calkinsia'' is a

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

of excavates comprising the single species ''Calkinsia aureus''. It lives in low-oxygen seafloor environments. It is not classified in any of the three well-known groups of the Euglenozoa (

Kinetoplastida Kinetoplastida (or Kinetoplastea, as a class) is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of an organelle with a large massed DNA called kinetoplast (hence the name). The organisms are ...

, Euglenida or

Diplonemida Diplonemidae is a family of biflagellated unicellular protists that may be among the more diverse and common groups of planktonic organisms in the ocean. Although this family is currently made up of three named genera; '' Diplonema'', '' Rhynchopu ...

), but is placed in its own group, the Symbiontida (along with some DNA sequences which were found in marine environments but not identified with known organisms). Some authors have classified ''Calkinsia'' alongside ''

Postgaardi ''Postgaardi mariagerensis'' is a species of single-celled eukaryote in the Euglenozoa. Some have classified it in a class called Postgaardea along with '' Calkinsia'', but as of 2009, ''Postgaardi'' is not well enough known to confidently deter ...

'', but ''Postgaardi'' has not been studied well enough to test this hypothesis. The genus name of ''Calkinsia'' is in honour of Gary Nathan Calkins (1869 – 1943), who was an American

protozoologist Protozoology is the study of protozoa, the "animal-like" (i.e., motile and heterotrophic) protists. The Protozoa are considered to be a subkingdom of Protista. They are free-living organisms that are found in almost every habitat. All humans have pr ...

and a professor at

Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...

. He wrote several landmark textbooks on the biology of the protozoa.

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