| This family is
made up of about 17 species of freshwater and occasionally brackish water
fishes. Found in tropical and subtropical waters in Asia, Indo-Australian
Archipelago, West Africa (Liberia), Mexico, Central and South America.
They are eel-like fishes with no pectoral or pelvic fins; rudimentary
dorsal and anal fins; and a caudal fin that is small or rudimentary, or
lacking altogether. Scales are absent or confined to the caudal region.
They have small eyes and lack swim bladders or ribs. Mostly air breathers.
Many are burrowers (Nelson
1994). All these characters can be considered preadaptive to
the hypogean environment. There are two genera
with two species each that are hypogean. Ophisternon is a genus of
six species of circumtropical distribution with a disjunct distribution of
species; they all lack scales. Monopterus is an Old World genus
represented by seven species that also lack scales; two of those species
are hypogean. The contention by
Galán (1982, 1995) that M.
boueti was found in caves is erroneous. Given the geographic proximity
of the two hypogean species of Monopterus, it would be interesting
to investigate the genetic relationships between both as well with their
putative ancestor M. albus. A depigmented individual of
Synbranchus marmoratus was collected in a cave in northeastern
Venezuela in 1979 (Galán
1982), but this fish recovered its pigmentation when exposed to
light. Further studies in this locality are needed in order to confirm the
troglomorphic nature of this potential hypogean population.
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Monopterus (Monopterus) eapeni
Talwar in Talwar & Jhingran, 1991
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Monopterus roseni
Bailey & Gans, 1998
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Ophisternon candidum
(Mees, 1962)
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Ophisternon infernale
(Hubbs, 1938)
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