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Student discovers new shrimp species by chance

When biology student Mike Groenhof was making a phylogenetic tree of fifty shrimp species for his internship, one specimen turned out to be an undescribed species. The animal was collected by Naturalis scientist 18 years ago, and had been under the radar ever since.

Naturalis marine biologist Bert Hoeksema organized an expedition to Indonesia in 2003, in order to better map the marine biodiversity of Kalimantan. During the expedition, many shrimps were collected and stored, and eighteen years later someone got around to putting them in order.

Mike Groenhof in one of the Naturalis depots.

Biology student Mike Groenhof (Leiden University) studied more than fifty species of shrimp on the basis of their morphology and genetics, for his internship with  Charles Fransen and Werner de Gier of Naturalis. During one of the DNA-analyses, the new species turned up.

Living with an oyster

The new species was found in a tropical oyster (Chama lazarus), making the shrimp a symbiont – an animal that lives with a host. There's several kinds of symbiosis, depending on whether the host benefits or suffers from the symbiont. In this particular case, there are no known effects on the oyster, so the new shrimp's lifestyle is classified as commensalism. There are hundreds of symbiotic shrimp, living in shells, corals, sponges and many other marine animals. 


Groenhof, Fransen and De Gier classified the animal as a member of the genus Odontonia, a group of shrimps that usually live in ascidians. In 2002 and 2018 other Odontonia species were discovered, including the so-called Hobbit shrimp, Odontonia bagginsi, described by De Gier and Fransen.

Odontia katoi, a close relative of the newly described species, living in an ascidian. Photo Charles Fransen

A new name

After a new species has been discovered, it needs to be formally descibed in a scientific publication, with illustrations of parts of the animal. Some species get a name based on their appearance (Odontonia rufopuncata, for instance, has red (rufo) dots (punctata), this new species has a name referring to the host: Odontonia kerangcaris. The name is based on the Indonesian word for shell ‘kerang’, and the Latin word for shrimp: ‘caris’. The publication appeared in Zootaxa last week.

Illustration of Odontonia kerangcaris.There is not yet found a live animal of this species.


Fransen, C. H. ., Groenhof, M., &  de Gier, W.(2021). Odontonia kerangcaris sp. nov., a new bivalve-associated shrimp (Crustacea, Decapoda, Palaemonidae) from East Kalimantan, revealing intrageneric host switching. Zootaxa, 5081(2), 275–285. https://doi.org/10.11646/zootaxa.5081.2.6

Text: Werner de Gier

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