Erythrosquilla is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of mantis shrimp

Mantis shrimp

Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...

, placed in its own 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...

 (Erythrosquillidae) and superfamily

Taxonomic rank

In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...

 (Erythrosquilloidea) comprising two species:

• Erythrosquilla hamano Ahyong, 2001
• Erythrosquilla megalops Manning & Bruce, 1984

The family is distinguished from other stomatopod families by the presence of a ridge on the mid-line of the 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...

.

Erythrosquilla megalops

E. megalops is only known from the waters off Somalia

Somalia

Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...

, in the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, which gives rise to the generic name ( being an old name for the Indian Ocean). The raptorial

Raptorial

The term raptorial implies much the same as "predatory", but most often refers to modifications of an arthropod's foreleg that make it function for the grasping of prey while it is consumed, where the gripping surfaces are formed from the opposing faces of two successive leg segments...

 claws each have five teeth, rather than the 8–9 seen in E. hamano.

Erythrosquilla hamano

E. hamano is known from Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese water in the East China Sea

East China Sea

The East China Sea is a marginal sea east of China. It is a part of the Pacific Ocean and covers an area of 1,249,000 km² or 750,000 square miles.-Geography:...

 and around Rottnest Island

Rottnest Island

Rottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. This apparently disjunct distribution

Disjunct distribution

In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...

 is also known in the parasquillid

Parasquillidae

Parasquillidae is a family of mantis shrimp containing the three genera Faughnia, Parasquilla and Pseudosquillopsis. It was previously included in the superfamily Gonodactyloidea, but that group was found to be paraphyletic, and a new superfmaily, Parasquilloidea was erected....

 mantis shrimp Pseudosquillopsis dofleini. Among the differences between it and E. megalops, the most obvious is that it has more teeth on the raptorial claw

Claw

A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...

than E. megalops.