Student discovers new shrimp species by chance

December 13th, 2021
Schematische pentekening van de garnaal Odontia kerancaris.

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 new species was discovered by chance during one of the DNA analyses: the genetic code of the specimen didn't match that of other species. The shrimp was collected by Naturalis scientists in 2003, and had been under the radar since then. 

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Naturalis marine biologist Bert Hoeksema organized an expedition to Indonesia that year, 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. 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 analyses, the new species turned up.

Mike Groenhof in de collectie van Naturalis
Biology student Mike Groenhof in one of the Naturalis depots. 

The new species was found in a tropical oyster (Chama lazarus), making the shrimp a "symbiont" – symbiotic animals live with a host. There's several kinds of symbiosis, depending on wether 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 als a member of the genus Odontonia, a group of shrimps that usually live in ascidians. In 2002 and 2018 other Odontonia species were discoverd, including the so-called Hobbit shrimp, Odontonia bagginsi, described by De Gier and Fransen

Odontia katoi, een verwante garnaal.
Odontia katoi, a close relative of the newly described species, living in an ascidian. Foto Charles Fransen.

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.