''Merodoras nheco'' is species 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 ...

, it is the only

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

''Merodoras'' of the

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

(

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Siluriformes)

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 ...

Doradidae 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 ...

Taxonomy

''Merodoras'' and its

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

''M. nheco'' were described in 2007. It belongs to the subfamily Astrodoradinae. This genus is most closely related to ''

Amblydoras ''Amblydoras'' is a genus of thorny catfishes native to rivers in tropical South America. ''Amblydoras'' is one of several genera classified within the subfamily Astrodoradinae. ''Amblydoras'' species range from about 7.5–10.2 centi ...

''.

Distribution and habitat

''Merodoras nheco'' inhabits a flooded portion of the upper

Paraguay River The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters in ...

basin in western

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 ...

called the ''Pantanal Matogrossense''. Here it lives in the

lentic A lake ecosystem or lacustrine ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example of lentic ecosystems (''lentic'' ref ...

lakes in flooded areas.

Appearance and anatomy

''M. nheco'' is like other doradids. It has three pairs of

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and s ...

(one pair maxillary, two pairs mental), strong

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

and

pectoral 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 ...

spines. ''M. nheco'' is differentiated from all other doradids by having its scutes with thorns directed ventrally in adults, and from all doradids except ''

Physopyxis cristata ''Physopyxis cristata'' is a species of thorny catfish endemic to 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 ov ...

'' by having an incomplete lateral line. It has a smooth dorsal fin spine, as opposed to a serrated one; the only other genus with smooth dorsal fin spines is ''

Anadoras ''Anadoras'' is a genus of thorny catfishes native to tropical South America. This genus has been assigned to the subfamily Astrodoradinae. Species There are currently four recognized species in this genus: * '' Anadoras grypus'' (Cope, 1872 ...

''. Also, it has a truncated

caudal 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 ...

. This species grows to a length of SL.

Ecology

''M. nheco'' is fed upon by southern caimans (''Caiman crocodilus yacare'') when its habitat dries over the winter, which makes these fish easier to catch. These fish are often

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People * Jim Host (born 1937), American businessman * Michel Host ...

s to

tongue worms The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus ''Linguatula'' to a vertebrate tongue; molecular studies point to them being degenerate crustacea ...

, which inhabit their swim bladders.

References

{{Taxonbar, from=Q3754485 Doradidae Freshwater fish of Brazil Endemic fauna of Brazil Taxa named by Horacio Higuchi Taxa named by José Luis Olivan Birindelli Taxa named by Leandro Melo de Sousa Taxa named by Heraldo Antonio Britski Fish described in 2007