Lepisosteus
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Lepisosteus (from Greek lepis (Template:Lang), 'scale' and osteon (Template:Lang), 'bone')<ref>Template:Cite book</ref> is a genus of gars in the family Lepisosteidae. It contains four extant species, found throughout eastern and central North America. It is one of two extant gar genera alongside Atractosteus.<ref name=":0" />
Distribution
Lepisosteus is known to be a freshwater fish. However, they do have the ability to survive in high salinity, and low oxygen water after gulping air.<ref name=":3">Template:Cite journal</ref><ref name=":1" /> Lepisosteus prefers to reside in brackish and shallow slow-moving waters, living usually in schools.<ref name=":0" /> The habitat range of this genus ranges on the Eastern coast from the Gulf of Mexico in Florida north to Quebec. Habitats can be found in the Missouri River Basin and Mississippi River drainage area, westward in the Rio Grande River basin of Southern Texas and Northern Mexico. There are also populations in the Great Lakes except for Lake Superior. Their range can occasionally reach out towards the Mobile Bay, Perdido Bay, and Mississippi Sound.<ref name=":0" /><ref name=":1" />
Lepisosteus appears to have a wider distribution in the past, as the extinct species L. bemisi inhabited intermountain lakes in the Green River Formation of what is now Wyoming, significantly west of the genus's modern range. The oldest record of the genus, a well-preserved skull from the Campanian, is known from the Oldman Formation of Canada.<ref name=":2" /> Even more removed from the genus's present distribution was L. indicus from the Maastrichtian-aged Lameta Formation and Intertrappean Beds of India. This species' inclusion in Lepisosteus is uncertain, as it was classified based on characteristics of the skull that were later found to be shared among many different gar taxa. However, phylogenies include it as more closely related to Lepisosteus than to Atractosteus or fossil gars.<ref name=":4">Template:Cite book</ref><ref>Template:Cite journal</ref><ref name=":5">Template:Cite journal</ref> Indeterminate gar remains, most likely of Lepisosteus, from the Palana Formation of India suggest that the genus may have persisted in India up to the Late Paleocene.<ref>Template:Cite journal</ref>
Description
These fish have ganoid scales on their elongated bodies with a single dorsal fin on the posterior side approximately one inch from their caudal fin.<ref name=":1">Template:Cite web</ref> Depending on the clarity of the water, Lepisosteus colors will change. In clear water they can have bright colors of green and silvery-white; alternatively if the water is brackish and cloudy, their colors will be more of a brown hue.<ref name=":0">Template:Cite web</ref> Hatchlings are approximately 8–10 mm in size. The average full-grown length of Lepisosteus varies from 34 to 78 inches depending on the species.<ref name=":1" /> In comparison to their long snouts, Lepisosteus have relatively small heads; however, their mouths full of sharp teeth.
Life history
Lepisosteus is a slow-growing genus generally living a long time. Female gars take 6 years to reach sexual maturity, grow larger, and live up to 22 years. Male gars reach maturity around 3 or 4 years after hatching. The males do not often live longer than 11 years.<ref name=":1" /><ref name=":42">Template:Cite web</ref> The longnose gar will migrate upstream to smaller streams with faster-moving water to spawn and lay eggs.<ref name=":1" /> Fish of this genus that are newly hatched will attach themselves vertically to submerged objects by an adhesive disc on their snout. The youth stay attached to the objects until the yolk sac is absorbed which usually takes about 9 days. After the yolk sac of an egg is absorbed, the roe hatches. Hatchlings stabilize to a horizontal position, take their first aerial breath, and begin feeding.
Diet
Because Lepisosteus has evolved to be a top predator, they are voracious eaters that eat a variety of other freshwater fish and crustaceans such as Ictiobus and blue crabs. Adults will float toward the surface of streams to scout prey that are below them while younger fish in this genus will hide in submersed vegetation to ambush hunt.<ref name=":12">Template:Cite web</ref> Studies have found this native North American species is a predator of invasive Asian carp, whose habitat they share.<ref>Template:Cite journal</ref> This genus is not generally used for recreational hunting because their roe is toxic to humans. There are no significant threats to these top predators other than habitat loss.<ref name=":12" /><ref name=":22">Template:Cite journal</ref> On the IUCN Red List of Threatened Species, this genus is listed as Least Concern.<ref>Template:Cite web</ref>
Taxonomy
Evolution
Phylogenetic evidence suggests that Lepisosteus is ancient genus that diverged from its only extant relative, Atractosteus, during the Early Cretaceous. As with Atractosteus, fossil evidence suggests that the ancestral range of the genus was likely centered around western North America during the Cretaceous and early Paleogene, until major climatic changes led to a shift in range to eastern North America by the late Paleogene.<ref name=":5" />
Species
The currently recognized species are: Lepisosteus oculatus, Lepisosteus osseus, Lepisosteus platostomus, and Lepisosteus platyrhincus.<ref name=":22" /> Three species formerly classified in Lepisosteus (tropical gar, Cuban gar, and alligator gar) are now assigned to the genus Atractosteus.<ref name=":42" />
| Image | Scientific name | Common name | Distribution |
|---|---|---|---|
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Lepisosteus oculatus Winchell, 1864 | Spotted gar | North America |
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Lepisosteus osseus Linnaeus, 1758 | Longnose gar | east coast of North and Central America in freshwater lakes and as far west as Kansas and Texas and southern New Mexico |
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Lepisosteus platostomus Rafinesque, 1820 | Shortnose gar | Montana to the west and the Ohio River to the east, southwards to the Gulf Coast. |
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Lepisosteus platyrhincus DeKay, 1842 | Florida gar | USA from the Savannah River and Ochlockonee River watersheds of Georgia and throughout peninsular Florida |
Fossil species
According to Grande, 2010. In addition, an indeterminate record (known as "Lepisosteus sp. A") is known from Campanian-aged Oldman Formation of Canada, and represents the oldest record of the genus.<ref name=":2">Template:Cite journal</ref>
- †Lepisosteus bemisi Grande, 2010<ref name=":2" />
- †"Lepisosteus" indicus (Woodward, 1890) (classification in Lepisosteus uncertain, but most closely related to it)<ref name=":4" /><ref name=":5" />
Dubious fossil species
- †Lepisosteus aganus (Cope, 1877) Nomen dubium
- †Lepisosteus bohemicus (Laube, 1901) Nomen dubium
- †Lepisosteus cominatoi Santos, 1984 Nomen dubium
- †Lepisosteus cycliferus (Cope, 1873) Nomen dubium
- †Lepisosteus fimbriatus Wood, 1846 Nomen dubium
- †Lepisosteus glaber Marsh, 1871 Nomen nudum
- †Lepisosteus integer (Cope, 1877) Nomen dubium
- †Lepisosteus knieskerni Fowler, 1911 Nomen dubium
- †Lepisosteus longus Lambe, 1908 Nomen dubium
- †Lepisosteus nahunticus (Cope, 1869) Nomen dubium
- †Lepisosteus notabilis Leidy, 1873 Nomen dubium
- †Lepisosteus occidentalis Leidy, 1856 Nomen dubium
- †Lepisosteus opertus Estes, 1964 Nomen dubium
- †Lepisosteus strausi Kinkelin, 1884 Nomen dubium
- †Lepisosteus suessoniensis Gervais, 1888 Nomen nudum
- †Lepisosteus whitneyi Marsh, 1871 Nomen nudum
Phylogeny
<ref name=":22" />