Acartia lefevreae is a species of copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

 belonging to the family Acartiidae

Acartiidae

Acartiidae is a family of calanoid copepods distinguishable by the rostral margin not being extended. They are epipelagic, planktonic animals, not being found below a depth of . There are over 100 described species distributed throughout the world's oceans, mainly in temperate areas....

. This species was discovered when specimens previously identified as Acartia clausi

Acartia clausi

Acartia clausi is a species of marine copepod belonging to the family Acartiidae. This species was previously thought to have a worldwide distribution but recent research has restricted its range to coastal regions of the north-east Atlantic Ocean as far north as Iceland, the Mediterranean Sea and...

were examined and found to belong to a separate species . Its range overlaps with that of A. clausi, being found in the western Mediterranean and the north east Atlantic as far north as the English Channel

English Channel

The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

, but it tends to be found in more brackish habitats such as estuaries.

This species is generally similar to A. clausi but is usually noticeably smaller (total length 0.8 - 0.9 mm) and differs in the arrangement and size of the spines on the back of the posterior body segment (metasome).