''Merodoras nheco'' is a species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, it is the only

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the

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 ...

''Merodoras'' of the

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

(

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Siluriformes)

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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 International_Code_of_Zoological_Nomenclature, 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 spe ...

''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 cent ...

''.

Distribution and habitat

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

Paraguay River The Paraguay River (''Ysyry Paraguái'' in Guarani language, Guarani, ''Rio Paraguai'' in Portuguese language, Portuguese, ''Río Paraguay'' in Spanish language, Spanish) is a major river in south-central South America, running through Brazil, Bol ...

basin in western

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

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, whisker like sensory organ near the mouth (sometimes called whiskers or tendrils). Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the z ...

(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 The fus ...

and

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

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'' by having an incomplete

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

. 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, 187 ...

''. Also, it has a truncated

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

. This species grows to a length of SL.

Ecology

''M. nheco'' is fed upon by

spectacled caiman The spectacled caiman (''Caiman crocodilus''), also known as the white caiman, common caiman, and speckled caiman, is a crocodilian in the family Alligatoridae. It is brownish-, greenish-, or yellowish-gray colored and has a spectacle-like ridge ...

s (''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 * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

s to tongue worms, which inhabit their swim bladders.

References

{{Taxonbar, from=Q3754485 Doradidae Thorny catfish of Brazil Endemic fish 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