Leuconidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of marine hooded shrimp (order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Cumacea

Cumacea

Cumacea is an order of small marine crustaceans, occasionally called hooded shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans.-Anatomy:...

). These malacostraca

Malacostraca

Malacostraca is the largest of the six classes of crustaceans, containing over 25,000 extant species, divided among 16 orders. Its members display a greater diversity of body forms than any other class of animals, and include crabs, lobsters, shrimp, krill, woodlice, scuds , mantis shrimp and many...

n crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s belong to the superorder Peracarida

Peracarida

The superorder Peracarida is a large group of malacostracan crustaceans, having members in marine, freshwater, and terrestrial habitats. They are chiefly defined by the presence of a brood pouch, or marsupium, formed from thin flattened plates borne on the basalmost segments of the legs Other...

, unlike true shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

, which are Eucarida

Eucarida

Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill and Amphionides. They are characterised by having the carapace fused to all thoracic segments, and by the possession of stalked eyes....

. The family was established by Georg Ossian Sars in his 1878 study of Mediterranean cumaceans.

Description

Leuconidae retain the original number of free thoracic

Thorax

The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

 somite

Somite

A somite is a division of the body of an animal. In vertebrates this is mainly discernible in the embryo stage; in arthropods it is a characteristic of a hypothetical ancestor.- In vertebrates :...

s, but do not possess a free telson

Telson

The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...

. Their mandibles

Mandible (arthropod)

thumb|250px|The mandibles of a [[Bull ant]]The mandible of an arthropod is either of a pair of mouthparts used for biting, cutting and holding food. Mandibles are often simply referred to as jaws. Mandibles are present in the extant subphyla Myriapoda , Crustacea and Hexapoda...

 are truncated dorsally

Dorsum (biology)

In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 to the molar. In males, the flagellum of the second antenna

Antenna (biology)

Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

 reaches beyond the hindmost edge of the carapace

Carapace

A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...

. Their gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s do not have gill plates or other supports.

The endopods (interior branches) of the uropods are present on two (or more rarely one) segments. The males of almost all Leuconidae also have pleopods, typically two pairs that lack an external process on the inner ramus. In females the second antenna is greatly reduced. They have exopods (outer branches) on the maxillipeds and on the first two pereopods, in females of some species often also on the third, and in the males of most species also on the third and fourth.

Genera

• Alloeoleucon Watling & McCann, 1997
• Americuma Watling, 1991
• Austroleucon Watling, 1991
• Bytholeucon Jones, 1991
• Coricuma Watling & Breedy, 1989
• Eudorella Norman, 1867
• Eudorellopsis Sars, 1882
• Hemileucon Calman, 1907
• Heteroleucon Calman, 1907
• Leucon Krøyer, 1846
• Nippoleucon Watling, 1991
• Ommatoleucon Watling, 1991
• Paraleucon Calman, 1907
• Phalloleucon Mühlenhardt-Siegel, 2008
• Pseudeudorella Mühlenhardt-Siegel, 2008 (formerly in Eudorella)
• Pseudoleucon Zimmer, 1903