''Leptochilichthys'' is a genus of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

es containing four species. ''Leptochilichthys'' is the only genus in the former family Leptochilichthyidae but is now included within the broader family

Alepocephalidae Slickheads, also known as nakedheads or smoothheads, are deep water fishes that belong to the family Alepocephalidae. They are most commonly found in the bathypelagic layer, which is approximately 3000m below the surface. They get their name from ...

.R. Betancur-Rodriguez, E. Wiley, N. Bailly, A. Acero, M. Miya, G. Lecointre, G. Ortí
''Phylogenetic Classification of Bony Fishes – Version 4''
(2016) Its name derives from the Greek λεπτός (''leptos'', "small"); χεῖλος (''cheilos'', "

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

"); and ἰχθύς (''ichthys'', "fish").

Species

The currently recognized species in this genus are: * '' Leptochilichthys agassizii'' ( Garman, 1899) (Agassiz' smooth-head) * '' Leptochilichthys microlepis'' ( Machida & Shiogaki, 1988) (smallscale smooth-head) * '' Leptochilichthys pinguis'' ( Vaillant, 1886) (Vaillant's smooth-head)

Description

Species in genus ''Leptochilichthys'' have toothless

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

e. The maxillae are considered especially long There are teeth on the palate and dentary. Many long

gill raker Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of th ...

s are also present. This genus does not exhibit any shoulder sac apparatus. Thirteen branchiostegal rays support the gill membranes behind the lower jaw. There may be 11 to 21 dorsal fin rays, and 11–18 anal fin rays. These species have 47–64

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

scales. Species of this genus have between 47 and 58 vertebrae. They can reach up to in length.

Distribution and habitat

''Leptochilichthys'' species are found in

deep sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low tempe ...

regions in the eastern

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, western Indian, and eastern and western

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

Oceans. They are most commonly found at depths of and below, but are in general not well known. Some species in this genus, particularly ''L. agassizii'', may be

bathypelagic The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above and the abyssopelagic below. The bathypela ...

References

Alepocephalidae Ray-finned fish genera Taxa described in 1899 Taxa named by Samuel Garman {{Alepocephaliformes-stub