''Tarumania'' is a genus of

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

described in 2017. It contains a single species, ''Tarumania walkerae'', and constitutes the only genus in the family Tarumaniidae. ''T. walkerae'' is a predatory species that hunts among the

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

on the bottom of

flooded forest Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are foun ...

s in the Rio Negro drainage basin.

Discovery and taxonomy

The species first came to the attention of scientists in 2002 in the form of a poorly preserved juvenile specimen collected as part of a survey. The specimen possessed many unusual traits and could not be identified even to family level. Due to the poor preservation, no formal description was attempted until many years later, after the discovery of a living population and collection of better specimens. The genus name ''Tarumania'' was chosen after the site of first collection (the

Tarumã Mirim River The Tarumã Mirim River () is a river in the state of Amazonas, Brazil. It is a left tributary of the Rio Negro, which it enters west of the city of Manaus. Course The Tarumã Mirim drains the west part of the Tarumã Açu – Tarumã Mirim se ...

). ''Tarumania'' is a

characiform Characiformes is an order of Actinopterygii, ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A ...

, the order which includes

piranha A piranha (, or ; ) is any of a number of freshwater fish species in the subfamily Serrasalminae, of the family Serrasalmidae, in the order Characiformes. These fish inhabit South American rivers, floodplains, lakes and reservoirs. Although ...

s and

tetras Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological families Characidae, Alestidae (the "African tetras"), Lepidarchidae, Lebiasi ...

. Due to its distinctness from all other characiformes, the describers placed it in its own family, Tarumaniidae. Based on their morphological analysis they estimated Tarumaniidae to be most likely the sister group of

Erythrinidae The Erythrinidae are a family of fishes found in rivers and other freshwater habitats from Costa Rica south as far as Argentina. They are common and are caught with hooks by fishermen, partially because of their voracious behaviour. They are som ...

, the trahira family, but no DNA evidence was available to confirm or deny this.

Description and biology

''Tarumania'' possesses a very unusual

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

, divided into eleven separate compartments (as opposed to one or two in most fish) which extends along almost the entire length of the body. Its body is extremely elongated and oval-shaped, giving the fish an eel-like appearance. Like the unrelated Lepidogalaxias, they have a flexible "neck" that allows them to bend their head at a right angle relative to the trunk. All specimens of ''Tarumania'' were recovered from isolated pools among the leaf-litter of the forest, where they appear to hunt invertebrates such as

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

on the flooded forest floor. They are well adapted to swim amongst tangled

undergrowth In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but above ...

, with very mobile pelvic fins that move independently of each other and the ability to twist separately from the rest of the body. They are able to breathe air in shallow-water conditions, but the swim bladder is not involved. Instead they absorb oxygen through their

oral cavity A mouth also referred to as the oral is the body orifice through which many animals ingest food and vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also the first part of the alime ...

.Paleogene emergence and evolutionary history of the Amazonian fossorial fish genus Tarumania (Teleostei: Tarumaniidae)
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References

{{Taxonbar, from1=Q42882292, from2=Q36458114, from3=Q42882305 Characiformes Characoidei Monotypic fish genera