Sarcoglanidinae
Encyclopedia
Sarcoglanidinae is a subfamily of catfish
es (order
Siluriformes) of the family
Trichomycteridae
. It includes six genera
, Ammoglanis
, Malacoglanis, Microcambeva
, Sarcoglanis, Stauroglanis, and Stenolicmus.
. 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
relationship to Glanapteryginae
. Like the members of this subfamily, many glanapterygines are sand-dwelling fish.
; Microcambeva species are known from southeastern Brazil
. Despite their scarcity in museum collections, it has been suggested that it is possible that sarcoglanidines occur throughout the entire Amazon basin as well as the Orinoco
basins.
Sarcoglanidines usually live in sandy banks of rivers and streams. They are sand-dwellers that feed on minute arthropod
s.
s (1.0 in
) 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
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 the head. Sarcoglanis simplex and Malacoglanis gelatinosus possess an uncommonly deep body, a hypertrophied sac-like adipose organ
above the pectoral fin, and the absence of premaxilla
ry teeth. These two species along with Stauroglanis gouldingi have few or no opercular and interopercular odontode
s.
The subfamily has been characterized, among other things, by a toothless upper jaw, the presence of an adiposelike fin, and the pectoral-fin rays projecting beyond the fin membrane.
Catfish
Catfishes 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 heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
es (order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Siluriformes) of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Trichomycteridae
Trichomycteridae
Trichomycteridae is a family of catfishes commonly known as the pencil or parasitic catfishes. This family includes the infamous candiru fish, feared by some people for its alleged habit of entering into the urethra of humans....
. It includes six genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, Ammoglanis
Ammoglanis
Ammoglanis is a genus of catfishes of the family Trichomycteridae. It includes three species, A. amapaensis, A. diaphanus and A. pulex.-Taxonomy:...
, Malacoglanis, Microcambeva
Microcambeva
Microcambeva is a genus of catfishes of the family Trichomycteridae. It includes three species, M. draco, M. barbata and M. ribeirae....
, Sarcoglanis, Stauroglanis, and Stenolicmus.
Taxonomy
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 monotypicMonotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
. 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
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
relationship to Glanapteryginae
Glanapteryginae
Glanapteryginae is a subfamily of catfishes of the family Trichomycteridae. It includes four genera, Glanapteryx, Listrura, Pygidianops, and Typhlobelus.-Phylogeny:...
. Like the members of this subfamily, many glanapterygines are sand-dwelling fish.
Distribution and habitat
All genera except Microcambeva are endemic to the Amazon RiverAmazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
; Microcambeva species are known from southeastern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. Despite their scarcity in museum collections, it has been suggested that it is possible that sarcoglanidines occur throughout the entire Amazon basin as well as the Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...
basins.
Sarcoglanidines usually live in sandy banks of rivers and streams. They are sand-dwellers that feed on minute arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s.
Description
Sarcoglanidines are all very small (to the extent of some species being considered miniaturized), usually not exceeding 25 millimetreMillimetre
The millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length....
s (1.0 in
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
) SL
Fish measurement
Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...
; 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
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
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 the head. Sarcoglanis simplex and Malacoglanis gelatinosus possess an uncommonly deep body, a hypertrophied sac-like adipose organ
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
above the pectoral fin, and the absence of premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry teeth. These two species along with Stauroglanis gouldingi have few or no opercular and interopercular odontode
Odontode
Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They comprise a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to that of teeth. They generally do not have the same...
s.
The subfamily has been characterized, among other things, by a toothless upper jaw, the presence of an adiposelike fin, and the pectoral-fin rays projecting beyond the fin membrane.