Atyopsis is a genus of freshwater

Fresh Water

Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

 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...

 from Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

. It was erected in 1983 by Fenner A. Chace, Jr.

Fenner A. Chace, Jr.

Fenner Albert Chace, Jr. was an American carcinologist. He was born in Fall River, Massachusetts, and studied at Harvard University, before becoming a curator at that university's Museum of Comparative Zoology...

 for two species formerly treated in the genus Atya

Atya

Atya is a genus of freshwater shrimp of the family Atyidae, ranging through the Antilles and along the Atlantic and Pacific slopes of Central and South America and in western Africa.-Species:* Atya africana Bouvier, 1904...

. It differs from Atya by various characters, including the form 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...

 (which is longest at the corners in Atyopsis, but not in Atya) and the presence of a "massive spur" on the male third pereiopod.

The genus comprises two species, Atya spinipes and Atyopsis moluccensis. No fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 representatives are known. They are found on high island

High island

In geology , a high island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, whose origin is due to sedimentation or uplifting of coral reefs.-Definition and origin:...

s from Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

 to the Samoan Islands

Samoan Islands

The Samoan Islands or Samoa Islands is an archipelago covering in the central South Pacific, forming part of Polynesia and the wider region of Oceania...

, and as far north as Okinawa, as well as on the Asian mainland from the Malay Peninsula

Malay Peninsula

The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...

 to India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. The two species differ in the number of teeth on the underside of the rostrum

Rostrum (anatomy)

The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

, A. spinipes having 2–6, while A. moluccensis has 7–16.