''Ammocrypta'' is a genus of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, commonly known as the sand darters, which is classified in the subfamily

Etheostomatinae Etheosomatidae is a species rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The famil ...

, part of the

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 ...

Percidae The Percidae are a family of ray-finned fish, part of the order Perciformes, which are found in fresh and brackish waters of the Northern Hemisphere. The majority are Nearctic, but there are also Palearctic species. The family contains more than ...

which also includes the

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Per ...

es, ruffes and pikeperches. The species in the genus occur in eastern North America in

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and the

continental United States The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...

Characteristics

''Ammocrypta'' species are characterised by having rather elongate and slender bodies. Their bodies are translucent and there is only a single spine in the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

. They also have Spreitzer

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

, that is that the first three vertebrae of the backbone, counting from the head, have an open

haemal arch A haemal arch also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the hae ...

which allows for the fish's

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

to expand. They have the habit of burying into the sand or gravel bed of streams, only their eyes being visible. The translucence of their bodies and their habit of burying themselves gives them some protection against predation. The shared morphological characteristics of ''Ammocrypta'' with its sister taxon ''Crystallaria'' include the possession of complete lateral lines and unbroken canal on the head. They also share high meristic counts which are thought to be indications of basal morphology, referred to as

plesiomorphies In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

Distribution

''Ammocrypta'' is found in eastern North America where thy are found across the central part of the coastal plain of the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

, the whole of the drainage basin of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it ...

and of the Ohio River, the Lake St Clair system as well as the lower drainage basins of

Lake Huron Lake Huron ( ) is one of the five Great Lakes of North America. Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Straits of Ma ...

and

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh w ...

Species

The currently recognized species in this genus are: * '' Ammocrypta beanii'' D. S. Jordan, 1877 (Naked sand darter) * '' Ammocrypta bifascia''

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, 1975 (Florida sand darter) * ''

Ammocrypta clara The western sand darter (''Ammocrypta clara'') is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to th ...

'' D. S. Jordan &

Meek Meekness is an attribute of human nature and behavior that has been defined as an amalgam of righteousness, inner humility, and patience. Meekness has been contrasted with humility alone insomuch as humility simply refers to an attitude towards o ...

, 1885 (Western sand darter) * '' Ammocrypta meridiana''

, 1975 (Southern sand darter) * ''

Ammocrypta pellucida The eastern sand darter (''Ammocrypta pellucida'') is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. The eastern sand ...

Putnam Putnam may refer to: People * Putnam (surname) Places Canada * Putnam, Ontario, community in Thames Centre United States * Putnam, Alabama * Putnam, Connecticut, a New England town ** Putnam (CDP), Connecticut, the main village in the town ...

, 1863 (Eastern sand darter) * '' Ammocrypta vivax'' O. P. Hay, 1882 (Scaly sand darter)

Taxonomy

''Ammocrypta'' is the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of the genus '' Crystallaria'' and together these genera are the sister taxon of the clade consisting of the speciose genus ''

Etheostoma ''Etheostoma'' is a genus of small freshwater fish in the family Percidae native to North America. Most are restricted to the United States, but species are also found in Canada and Mexico. They are commonly known as darters, although the term "d ...

'' and ''

Nothonotus ''Nothonotus'' is a genus or subgenus of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to the southeastern United S ...

''. Some authorities regard ''Crystallaria'' as a

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed betw ...

of ''Ammocrypta''.

References

{{Authority control Etheostomatinae Taxa named by David Starr Jordan