''Ammoglanis'' is a

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 ...

pencil catfish 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 ...

es native to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Taxonomy

The

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

position of ''A. pulex'' is problematic. It seems to be closely related to ''A. diaphanus'' due to some derived characters of the internal anatomy, but a conclusive assessment of its relationships has not been prevented by its

paedomorphic Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny in modern humans is more signi ...

features and scarcity of study material. This generic placement seems to be well supported. The relationships of the genus ''Ammoglanis'' are unknown; it is thought that this genus along with undescribed forms are the

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 ...

to a large intrafamilial

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

composed of several genera and subfamilies. In the interim, this genus is included within

Sarcoglanidinae The Sarcoglanidinae are a subfamily of catfishes (order Siluriformes) of the family Trichomycteridae. It includes six genera: '' Ammoglanis'', '' Malacoglanis'', '' Microcambeva'', '' Sarcoglanis'', '' Stauroglanis'', and '' Stenolicmus''. Taxono ...

Species

There are currently five recognized species in this genus: * '' Ammoglanis amapaensis'' Mattos,

Costa Costa may refer to: Biology * Rib (Latin: ''costa''), in vertebrate anatomy * Costa (botany), the central strand of a plant leaf or thallus * Costa (coral), a stony rib, part of the skeleton of a coral * Costa (entomology), the leading edge of th ...

& Gama, 2008 * '' Ammoglanis diaphanus''

, 1994 *'' Ammoglanis natgeorum'' *'' Ammoglanis obliquus'' * '' Ammoglanis pulex''

de Pinna De Pinna was a high-end clothier for men and women founded in New York City in 1885, by Alfred De Pinna (1831–1915), a Sephardic Jew born in England. They also sold menswear-inspired clothing for women that was finely tailored. The flagship sto ...

& Winemiller, 2000

Distribution

''A. amapaensis'' originates from three different drainages of the Amazon River, the

Jari Jari may refer to: Finnish male given name The name ''Jari'' derives from the Finnish name ''Jalmari'', which in turn derives from the Old Norse male name ''Hjalmar'' or ''Hjálmarr'' (''hjalmr'' 'helmet' + ''arr'' 'warrior/army'). With the influe ...

, Amapari, and Araguari River. ''A. diaphanus'' originates from a stream tributary to the

Javaés River The Javaés River ( or ''Braço Menor do Rio Araguaia'', Javaé: ♂ ''Bero Biòwa'' eˈɾo bɪɔˈwa ♀ ''Bèraku Bikòwa'' ɛɾaˈku bɪkɔˈwa is a river of Tocantins state in central Brazil and part of the Tocantins basin. It is a tributary ...

of the

Araguaia River The Araguaia River ( , Karajá language, Karajá: ♂ ''Berohokỹ'' eɾohoˈkə̃ ♀ ''Bèrakuhukỹ'' ɛɾakuhuˈkə̃ is one of the major rivers of Brazil, and a tributary of the Tocantins River. Geography The Araguaia River comes from ...

basin in

Tocantins Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 2014 ...

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 ...

. ''A. pulex'' originates from the Paria Grande River, the Pamoni River, and Caño Garrapata of

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

. ''A. obliquus'' is only known from the Rio Preta da Eva drainage basin.

Description

''Ammoglanis'' species grow to about SL. ''A. pulex'' is among the smallest known vertebrates. ''A. pulex'' can be distinguished from ''A. diaphanus'' by a number of characteristics, including the presence of a faint pattern of eight bands formed by internal

chromatophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopod A cephalopod is any member o ...

s and the lack of teeth.

Ecology

''A. diaphanus'' inhabits shallow, narrow, clear water, moderately swift-flowing stream and is found buried in the sand. It feeds on

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and a

cladocera The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 sp ...

ns. ''A. pulex'' is a translucent light-pink fish that camouflages well in sand. ''A. pulex'' is found in sand banks near the shorelines of clear water and slightly tea-stained streams. Apparently

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

by daylight, it is found buried in coarse clear sand at the stream edge, in areas shaded by dense tropical rainforest. The waters are with slow current, pH varying between 5.5–6.2, and temperature between . ''A. pulex'' is thought to feed on microscopic fauna like

protozoa Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

s, and

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s since it inhabits interstitial spaces among sand grains in nutrient-poor, clear-water and backwater streams.

References

{{Taxonbar, from=Q4747258 Trichomycteridae Catfish of South America Fish of the Amazon basin Freshwater fish genera Catfish genera