The Sarcoglanidinae are a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

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, ...

es (order Siluriformes) of the family

Trichomycteridae Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish (''Vandellia cirrhosa''), feared by some people for its alleged habit of entering into the urethra of hum ...

. It includes six

genera 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 nomenclat ...

: '' Ammoglanis'', '' Malacoglanis'', '' Microcambeva'', '' Sarcoglanis'', '' Stauroglanis'', and '' Stenolicmus''.

Taxonomy

The subfamily Sarcoglanidinae was first established in 1966 for ''Sarcoglanis simplex'' and ''Malacoglanis gelatinosus''. A third species of the subfamily, ''Stauroglanis gouldingi'', was described about 25 years later. Descriptions of additional species have followed, though most genera remain

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

. The relationships of the genus ''Ammoglanis'' with other sarcoglanidines are not well-established; however, this genus is currently included within Sarcoglanidinae. This subfamily has been proposed to have a

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

relationship to

Glanapteryginae The Glanapteryginae are a subfamily of catfishes (order Siluriformes) of the family Trichomycteridae. It includes four genera, ''Glanapteryx'', '' Listrura'', '' Pygidianops'', and '' Typhlobelus''. Phylogeny Monophyly of the subfamily is suppor ...

. Like the members of this subfamily, many glanapterygines are sand-dwelling fish.

Distribution and habitat

All genera except ''Microcambeva'' are

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 elsew ...

to the

Amazon River The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile. The headwaters of t ...

; ''Microcambeva'' species are known from southeastern

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 ...

. Despite their scarcity in museum collections, sarcoglanidines possibly occur throughout the entire Amazon and the

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

basins. Sarcoglanidines usually live in sandy banks of rivers and streams, feeding on minute

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

Description

Sarcoglanidines are all very small (to the extent of some species being considered 'miniaturized'), usually not exceeding 25 mm (1.0 in) in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

(SL); ''Microcambeva ribeirae'' is the largest species, reaching 48 mm (1.9 in) SL. All except one species are poorly pigmented, with a translucent body in life. The 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 some ...

present in other trichomycterids are also present in these fish, though nasal barbels tend to be reduced. In addition, some taxa have barbel-like structures on the ventral surface of their heads. ''Sarcoglanis simplex'' and ''Malacoglanis gelatinosus'' possess an uncommonly deep body, a hypertrophied sac-like adipose organ above the

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 ...

, and the absence of

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

ry teeth. These two species, along with ''Stauroglanis gouldingi'', have few or no opercular and interopercular

odontode Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They consist of a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to th ...

s. The subfamily has been characterized, among other things, by a toothless upper jaw, the presence of an adipose-like fin, and the pectoral-fin rays projecting beyond the fin membrane.

References

{{Taxonbar, from=Q7423582 Trichomycteridae Fish of South America Ray-finned fish subfamilies Taxa named by George S. Myers