''Aenigmachanna'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Ananbantiformes. It is the only genus in the family Aenigmachannidae, or dragon snakeheads. It contains two species, both of which are largely restricted to subterranean habitats in southwestern

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, namely in the Western Ghats foothills in the state of

Kerala Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South ...

. Both of the species in this genus display a unique array of traits that distinguish them from their closest living relatives, the true snakeheads in the family

Channidae The snakeheads are members of the freshwater perciform fish family Channidae, native to parts of Africa and Asia. These elongated, predatory fish are distinguished by their long dorsal fins, large mouths, and shiny teeth. They breathe air with ...

. These include a much longer and more slender body, numerous scales, a very long

anal 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 se ...

, and a lack of ability to maintain

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

. Molecular analyses indicate that they split off from Channidae around 34 or 109 MYA. This may indicate that Aenigmachannidae is a uniquely

Gondwanan Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

lineage, and if the higher end of estimations is correct, it may have survived the breakup of the Gondwanan supercontinent around 120 MYA. They are unique among

cavefish Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish and hypog ...

for being one of the few cave-dwelling members of the large clade

Percomorpha Percomorpha () is a large clade of ray-finned fish that includes the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish. Evolution Percomorpha are the most diverse group of teleost fish today. Teleosts, an ...

. Despite their habitat, they physically display little

troglomorphism Troglomorphism is the morphological adaptation of an animal to living in the constant darkness of caves, characterised by features such as loss of pigment, reduced eyesight or blindness, and frequently with attenuated bodies and/or appendages. The ...

aside from a slightly reduced pigmentation, indicating that they either colonized the caves relatively recently or that they are subtroglophiles that mostly live underground, but depend on aboveground habitats for some functions. Due to their restricted habitat and unique nature, both are considered

relict species In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a ...

Taxonomy

Species

* '' Aenigmachanna gollum''

Britz Britz () is a German locality (''Ortsteil'') within the Berlin borough (''Bezirk'') of Neukölln. History The village of ''Britzig'' was first mentioned in 1273. It was incorporated by the 1920 Greater Berlin Act. It is known for being the sit ...

, Anoop, Dahanukar and Raghavan, 2019 (Gollum snakehead) * '' Aenigmachanna mahabali''

Kumar A coin, around 200 BCE, of the Yaudheyas with depiction of Kumāra Karttikeya">Yaudheyas.html" ;"title="BCE, of the Yaudheyas">BCE, of the Yaudheyas with depiction of Kumāra Karttikeya Kumar (; Sanskrit language, Sanskrit: wikt:कुमा ...

Basheer Bashir or Basheer or the francicized Bachir or Bechir ( ar, بشير) is a male given name. Derived from Arabic, it means "the one who brings good news". It is also a surname. Bashir may refer to: Mononym * Bashir I, Lebanese emir of the Shih ...

, and

Ravi Ravi may refer to: People * Ravi (name), including a list of people and characters with the name * Ravi (composer) (1926–2012), Indian music director * Ravi (Ivar Johansen) (born 1976), Norwegian musical artist * Ravi (music director) (1926–201 ...

, 2019 (Mahabali snakehead) The genus was initially described in early 2019 to serve as a monotypic genus for ''A. gollum'', the first species to be described in the genus. Later in the year, ''A. mahabali'' was described as a distinct species, indicating that there were indeed multiple species in the genus.

References

{{Taxonbar, from=Q64481860 Cave fish Fauna of Kerala Freshwater fish of India Endemic fauna of India Endemic fauna of the Western Ghats Taxa named by Ralf Britz, Taxa named by V.K. Anoop, Taxa named by Neelesh Dahanukar and Taxa named by Rajeev Raghavan