The Aeglidae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of freshwater

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s currently restricted to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

. They are the only

anomura Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word ''crab'', all true crabs are in the sister group to the Anomura, the Brachyura (the two grou ...

ns to be found in fresh water except for a single

hermit crab Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an as ...

species, '' Clibanarius fonticola'', on

Espiritu Santo Espiritu Santo (, ; ) is the largest island in the nation of Vanuatu, with an area of and a population of around 40,000 according to the 2009 census. Geography The island belongs to the archipelago of the New Hebrides in the Pacific region o ...

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of no ...

. They live between 20° S and 50° S, at altitudes between .

Description

Aeglids resemble

squat lobster Squat lobsters are dorsoventrally flattened crustaceans with long tails held curled beneath the cephalothorax. They are found in the two superfamilies Galatheoidea and Chirostyloidea, which form part of the decapod infraorder Anomura, alongsi ...

s in that the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

is partly tucked under the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

. The notable

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

in the abdomen is related to the behaviour of carrying fertilised eggs on the pleopods. The carapace length of the largest species may approach , but most are considerably smaller. Aeglids are

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

, preferring plant matter, but also eating adult

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estim ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

and fly

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e. The internal anatomy has been described for ''Aegla cholchol'' and generally resembles that of other anomurans, particularly galatheoid squat lobsters. The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

of the antennal gland bladder differs from that in other anomurans in having a twisted tubular structure which was interpreted as an adaption to the freshwater lifestyle.

Life cycle

Mating is preceded by a period of

courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...

, and does not coincide with moulting, as it does in many other

decapods The Decapoda or decapods (literally "ten-footed") are an order (biology), order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, Caridea, shrimp and Dendrobranchiata, prawns. Most ...

. The

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

of aeglids hatch as juveniles which closely resemble the adults. They are cared for by their parents and live at the bottom of the body of water.

Extant taxa

''Aegla'', the only extant genus in the family, contains around 74 described extant species. Of the 63 species and subspecies described by 2008, two are found in lakes, four in

caves A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

, and the remaining 57 are found mainly in rivers. 42 species are found in

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, all restricted to the country's southern and

southeastern The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each se ...

regions ( Rio Grande do Sul alone is home to 24). Other countries with species are

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, Bolivia,

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

. More than a third of the species are considered

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

, and in Brazil alone 26 species are officially recognized as threatened, including 8 critically endangered.

Species

This list contains all the described species : *'' Aegla abtao'' Schmitt, 1942 *'' Aegla affinis'' Schmitt, 1942 *'' Aegla alacalufi'' Jara & López, 1981 *'' Aegla araucaniensis'' Jara, 1980 *'' Aegla bahamondei'' Jara, 1982 *'' Aegla brevipalma'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2012 *'' Aegla camargoi'' Buckup & Rossi, 1977 *'' Aegla castro'' Schmitt, 1942 *'' Aegla cavernicola'' Türkay, 1972 *'' Aegla cholchol'' Jara & Palacios, 1999 *'' Aegla concepcionensis'' Schmitt, 1942 *'' Aegla denticulata'' Nicolet, 1849 *'' Aegla expansa'' Jara, 1992 *'' Aegla franca'' Schmitt, 1942 *'' Aegla franciscana'' Buckup & Rossi, 1977 *'' Aegla georginae'' Santos & Jara ''in'' Santos ''et al.'', 2013 *'' Aegla grisella'' Bond-Buckup & Buckup, 1994 *'' Aegla hueicollensis'' Jara & Palacios, 1999 *'' Aegla humahuaca'' Schmitt, 1942 *'' Aegla inconspicua'' Bond-Buckup & Buckup, 1994 *'' Aegla inermis'' Bond-Buckup & Buckup, 1994 *'' Aegla intercalata'' Bond-Buckup & Buckup, 1994 *'' Aegla intermedia'' Girard, 1855 *'' Aegla itacolomiensis'' Bond-Buckup & Buckup, 1994 *'' Aegla jarai'' Bond-Buckup & Buckup, 1994 *'' Aegla jujuyana'' Schmitt, 1942 *'' Aegla laevis'' (Latreille, 1818) *'' Aegla lata'' Bond-Buckup & Buckup, 1994 *'' Aegla leachi'' Bond-Buckup & Buckup ''in'' Santos ''et al.'', 2012 *'' Aegla leptochela'' Bond-Buckup & Buckup, 1994 *'' Aegla leptodactyla'' Buckup & Rossi, 1977 *'' Aegla ligulata'' Bond-Buckup & Buckup, 1994 *'' Aegla longirostri'' Bond-Buckup & Buckup, 1994 *'' Aegla ludwigi'' Santos & Jara ''in'' Santos ''et al.'', 2013 *'' Aegla manni'' Jara, 1980 *'' Aegla marginata'' Bond-Buckup & Buckup, 1994 *'' Aegla manuniflata'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2009 *'' Aegla microphthalma'' Bond-Buckup & Buckup, 1994 *'' Aegla muelleri'' Bond-Buckup & Buckup ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla neuquensis'' Schmitt, 1942 *'' Aegla oblata'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2012 *'' Aegla obstipa'' Bond-Buckup & Buckup, 1994 *'' Aegla occidentalis'' Jara, Pérez-Losada & Crandall, 2003 *'' Aegla odebrechtii'' Müller, 1876 *'' Aegla papudo'' Schmitt, 1942 *'' Aegla parana'' Schmitt, 1942 *'' Aegla parva'' Bond-Buckup & Buckup, 1994 *'' Aegla paulensis'' Schmitt, 1942 *'' Aegla perobae'' Hebling & Rodrigues, 1977 *'' Aegla pewenchae'' Jara, 1994 *'' Aegla plana'' Buckup & Rossi, 1977 *'' Aegla platensis'' Schmitt, 1942 *'' Aegla pomerana'' Bond-Buckup & Buckup ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla prado'' Schmitt, 1942 *'' Aegla renana'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2010 *'' Aegla ringueleti'' Bond-Buckup & Buckup, 1994 *'' Aegla riolimayana'' Schmitt, 1942 *'' Aegla rossiana'' Bond-Buckup & Buckup, 1994 *'' Aegla rostrata'' Jara, 1977 *'' Aegla saltensis'' Bond-Buckup & Jara ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla sanlorenzo'' Schmitt, 1942 *'' Aegla scamosa'' Ringuelet, 1948 *'' Aegla schmitti'' Hobbs III, 1979 *'' Aegla septentrionalis'' Bond-Buckup & Buckup, 1994 *'' Aegla serrana'' Buckup & Rossi, 1977 *'' Aegla singularis'' Ringuelet, 1948 *'' Aegla spectabilis'' Jara, 1986 *'' Aegla spinipalma'' Bond-Buckup & Buckup, 1994 *'' Aegla spinosa'' Bond-Buckup & Buckup, 1994 *'' Aegla strinatii'' Türkay, 1972 *'' Aegla talcahuano'' Schmitt, 1942 *'' Aegla uruguayana'' Schmitt, 1942 *'' Aegla violacea'' Bond-Buckup & Buckup, 1994

Fossil taxa

''Haumuriaegla''

''Haumuriaegla glaessneri'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

known only from fossils of

Haumurian While also using the international geologic time scale, many nations–especially those with isolated and therefore non-standard prehistories–use their own systems of dividing geologic time into epochs and faunal stages. In New Zealand, these epo ...

age (

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

) found near Cheviot, New Zealand. At the time of its discovery, ''Haumuriaegla'' was the only known fossil from the family and the only marine member.

''Protaegla''

''Protaegla miniscula'' was discovered in rocks of

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

age from the Tlayúa Formation, near Tepexi de Rodríguez,

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Evolution

The family as a whole is thought to have originated around 75 million years ago in a marine environment, and then entered South America from the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

side during the Oligocene.

References

External links

* {{Taxonbar, from=Q4687643 Anomura Freshwater crustaceans of South America Extant Albian first appearances Decapod families Taxa named by James Dwight Dana