''Typhleotris mararybe'' is a critically endangered species of

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the family

Milyeringidae Milyeringidae, the blind cave gobies, is a small family of gobies, in the order Gobiiformes. There are two genera and six species within the family, which is considered to be a subfamily of the Eleotridae by some authorities. Milyeringidae incl ...

, the blind cave gobies. It is a

troglobitic A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...

species

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 cave habitat in southwestern

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

. It is unique among known cave-dwelling fish in that is both blind and darkly pigmented.Sparks, J. S. and P. Chakrabarty. (2012)
Revision of the endemic Malagasy cavefish genus ''Typhleotris'' (Teleostei: Gobiiformes: Milyeringidae), with discussion of its phylogenetic placement and description of a new species.
''American Museum Novitates'' 3764, 1-28. It has well-developed nonvisual sensory systems and dives to avoid approaching objects. The fish was first collected in 2008 and was described to science as a new species in 2012.

Description

''Typhleotris mararybe'' is about long. The body is uniformly dark brown in color, and the fins are mostly white with brown bases. Its sensory systems include a series of pores on its head, but it lacks eyes. The fish is relatively slow-moving, but more responsive to approaching objects than the closely related '' T. madagascariensis'', diving to avoid them. It can be distinguished from other members of genus ''

Typhleotris ''Typhleotris'' is a genus of cavefish that are endemic to caves in southwestern Madagascar. Although traditionally considered to belong to the family Eleotridae, studies show that they represent a distinct and far-separated lineage together wit ...

'' by its dark pigmentation and aspects of its bone structure. ''T. mararybe'' is possibly the

sister species 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 ...

of ''T. madagascariensis'', as the two share characteristics in common that '' T. pauliani'', the only other member of the genus, does not. ''T. mararybe'' may have

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

from an ancestral species that lacked pigmentation and was blind, but that pigmentation was regained for

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

in parts of the cave that receive sunlight.

Habitat

''Typhleotris mararybe'' is one of four cave-dwelling fishes in Madagascar. It was initially known from only a single cave, a

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

called the Grotte de Vitane near

Itampolo Itampolo is a town and commune ( mg, kaominina) in southwestern Madagascar. It belongs to the district of Ampanihy, which is a part of Atsimo-Andrefana Region. The population of the commune was estimated to be approximately 32,000 in 2001 commune ...

, where two specimens were collected, but has later been discovered to occur in four additional sinkholes/caves in the region. It is overall less widespread and common than ''T. madagascariensis'', which also occurs in the five caves/sinkholes inhabited by ''T. mararybe''. Despite this, direct

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

between the two species is not known.

Taxonomic evaluation

''Typhleotris mararybe'' was described from the two specimens, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

and the

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

, in 2012. It was published in ''

American Museum Novitates ''American Museum Novitates'' is a peer-reviewed academic journal published by the American Museum of Natural History. It was established in 1921. According to the ''Journal Citation Reports'', the journal has a 2013 impact factor The impact f ...

'', a

journal A journal, from the Old French ''journal'' (meaning "daily"), may refer to: *Bullet journal, a method of personal organization *Diary, a record of what happened over the course of a day or other period *Daybook, also known as a general journal, a ...

of the

American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...

. Locals sometimes enter the Grotte de Vitane cave where it was first discovered, but were unaware of the species. The specific name was derived from the Malagasy words ''marary'' (ill or sick), and ''be'' (big), combined to mean "very sick" or "big sickness". It commemorates an unknown severe illness suffered by members of the field team after their

snorkeling Snorkeling ( British and Commonwealth English spelling: snorkelling) is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped breathing tube called a snorkel, and usually swimfins. In cooler waters, a ...

expedition to survey the sinkhole.

References

{{Taxonbar, from=Q15709242 Typhleotris Cave fish Endemic fauna of Madagascar Fish described in 2012 Taxa named by Prosanta Chakrabarty