''Leptodoras'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
thorny catfish
The Doradidae are a family of catfishes also known as thorny catfishes, raphael catfishes or talking catfishes. These fish are native to South America, primarily the Amazon basin and the Guianas.
Doradids are omnivorous.
Taxonomy
As of 2007, 3 ...
es native to
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
.
Taxonomy
''Leptodoras'' is a
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
genus based on the single unique characteristic: presence of an infranuchal scute. This scute is the first in a series of well-developed midlateral scutes characteristic of most doradids.
It is one of the most
derived genera within the
clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
of fimbriate-barbel doradids.
The most closely related genus to ''Leptodoras'' is ''
Anduzedoras
''Anduzedoras oxyrhynchus'' is the only species in the genus ''Anduzedoras'' of the catfish (order Siluriformes) family Doradidae. This species originates from the Rio Negro and upper Orinoco River basins of Brazil and Venezuela
Venezuel ...
''.
This genus includes eleven species, making it the largest doradid genus.
There has been taxonomic confusion due to similarities of some species with each other and members of other genera. Misunderstood distributions and identities of some species added to this confusion. Most species were described from small geographic areas without information on their potential distributions. Also, specimens have been rare in museums until recently.
An assessment in 2005 diagnosed ''Leptodoras'' and its seven species while describing three new species.
[
]
Species
There are currently 12 recognized species in this genus:Steindachner
Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner descri ...
, 1915)
* '' Leptodoras juruensis'' Boulenger, 1898
* '' Leptodoras linnelli'' C. H. Eigenmann, 1912
* '' Leptodoras marki'' Birindelli & Sousa, 2010
Distribution
''Leptodoras'' species are distributed in large, predominantly lowland rivers east of the Andes
The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
throughout the northern half of South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
.[ Species are distributed throughout lowlands in the ]Orinoco
The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...
, Amazon
Amazon most often refers to:
* Amazon River, in South America
* Amazon rainforest, a rainforest covering most of the Amazon basin
* Amazon (company), an American multinational technology company
* Amazons, a tribe of female warriors in Greek myth ...
, and Tocantins
Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 2014 ...
basins and several coastal river systems that enter the Atlantic
The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...
between the mouths of the Orinoco and Amazon. ''Leptodoras'' is not known from west-Andean drainages or Atlantic-slope drainages south of the Tocantins.[
]
Description
''Leptodoras'' is easily recognized by its long conical snout and well-developed ''oral hood'' formed by the membranous union of maxillary barbels, paired jaw barbels on the chin, and lip
The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...
structures.[ It has fimbriate barbels.
]
Ecology
Most species of ''Leptodoras'' are truly benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...
and typically inhabit the deep swift-flowing waters of large rivers. Many species of ''Leptodoras'' migrate at dusk into shallow waters near shore to forage over beaches and shoals of sand or silt. Other species, such as ''L. juruensis'' and ''L. myersi'', appear more restricted to deep channel habitats. ''Leptodoras'' species are not known from elevation
The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...
s exceeding 500 metres (1600 ft) above sea level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
and most records are from below 200 m (660 ft).[
The oral hood found in ''Leptodoras'' species presumably facilitates the detection and ]suction
Suction is the day-to-day term for the movement of gases or liquids along a pressure gradient with the implication that the movement occurs because the lower pressure pulls the gas or liquid. However, the forces acting in this case do not orig ...
-feeding of shallowly buried invertebrate
Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s. Stomach contents typically include chironomid
Chironomidae , commonly known as non-biting midges or chironomids , are a family of Nematoceran flies with a global distribution. They are closely related to the families Ceratopogonidae, Simuliidae, and Thaumaleidae. Although many chironomid s ...
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e, sand, and detritus.[
]
References
{{Taxonbar, from=Q6528103
Doradidae
Fish of South America
Catfish genera
Taxa named by George Albert Boulenger
Freshwater fish genera