Diplomystidae, the velvet catfishes, are a family of primitive catfishes

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to freshwater habitats in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

and

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

in southern South America. It currently contains six species in two genera.

Taxonomy

In traditional schemes, the family Diplomystidae is the basal, primitive sister group to all other catfishes (Siluroidei). This is well supported by morphological evidence. Almost all molecular estimates of catfish phylogeny, by contrast, find Diplomystidae sister to Siluroidei, with Loricarioidei (the armoured catfish and relatives) the most basal group; though this may be an artifact of rapid evolution in loricarioids. Diplomystids retain more plesiomorphic characteristics than any other siluriforms, recent or fossil, including aspects of the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

ry bones,

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 some s ...

nare A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called tur ...

s, otic capsule, anterior

pterygoid Pterygoid, from the Greek for 'winglike', may refer to: * Pterygoid bone, a bone of the palate of many vertebrates * Pterygoid processes of the sphenoid bone ** Lateral pterygoid plate ** Medial pterygoid plate * Lateral pterygoid muscle * Medi ...

bones, Weberian complex centra, caudal skeleton, and fin rays, and

pectoral girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of ...

Monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

for Diplomystidae is well supported by synapomorphies of the

vomer The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right max ...

ine and

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

shapes, cranial articulation of the

hyomandibula The hyomandibula, commonly referred to as hyomandibular one( la, os hyomandibulare, from el, hyoeides, "upsilon-shaped" (υ), and Latin: mandibula, "jawbone") is a set of bones that is found in the hyoid region in most fishes. It usually plays ...

, and heavily

papillose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

skin. ''Olivaichthys'' is a genus erected by Gloria Arratia in 1987. However, many recent authors synonymize this genus with ''Diplomystes''. A molecular analysis has proposed that the trans-

Andean The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S l ...

''Diplomystes'' and the cis-Andean ''Olivaichthys'' are so closely related (in addition to the close morphological similarity), that ''Olivaichthys'' should not be recognized. However, this is strange, as recent divergence is unlikely with the species on either side of the Andes.

Description

Diplomystids are the only extant catfish family with teeth on a well-developed

(although this is also true of the extinct genus '' Hypsidoris''). Diplomystids possess maxillary barbels. The dorsal and pectoral fins have spines. The largest species reaches .

Ecology

Relatively little is known of the habits and life history of diplomystids. In Chile, diplomystids are mostly found to be benthic in fast-moving streams, and ''D. camposensis'' also occurs in lakes. ''O. viedmensis'' has been taken from rivers near sea level to about 1,900 m. Diplomystids are generalized carnivores that consume annelids,

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s, and

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s. Specimens of ''D. nahuelbutaensis'' from fast-flowing, moderate-elevation (370–520 m) tributaries of the Bío Bío River had eaten aquatic insect

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e, especially

chironomid The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...

s, and the relatively large decapod

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

Aegla The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu ...

''. Reproduction occurs at least during the austral summer based on captures of females with maturing eggs, and the juveniles reported here were collected in December.

Conservation

All diplomystids are considered to be potentially or actually threatened or endangered due to habitat deterioration and predation or competition by introduced trout, ''

Oncorhynchus mykiss The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coastal ...

'' and ''

Salmo trutta The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

''. ''D. chilensis'' may be extinct.

References

* {{Taxonbar, from=Q1572186 Catfish families Taxa named by Carl H. Eigenmann