Teleostei (teleosts) >
Saccopharyngiformes (Swallowers and gulpers) >
Monognathidae (Onejaws)
Etymology: Monognathus: Greek, monos = one + Greek, gnathos = jaw (Ref. 45335); nigeli: Named after Nigel Merrett who has provided the suthors with several specimens of Monognathus and was very helpful during their revisionary work.
Eponymy: Nigel Robert Merrett (d: 1940) is a British zoologist and ichthyologist. [...] (Ref. 128868), visit book page.
More on authors: Bertelsen & Nielsen.
Environment: milieu / climate zone / depth range / distribution range
Ecology
Marine; bathypelagic; depth range 1500 - 3910 m (Ref. 34506). Deep-water
Eastern Central Atlantic. High Seas only.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 5.7 cm TL male/unsexed; (Ref. 34506)
Short description
Identification keys | Morphology | Morphometrics
Dorsal soft rays (total): 82 - 95; Anal soft rays: 56 - 60. M. nigeli differs from the other species of the genus by the following combination of characters: head long with elongate, pointed snout and almost straight jaw, skull length 6.0-7.0% TL, rostral fang strongly hooked with distal part in a neatly right angle to dorsal profile of skull, predorsal length 14.5-18.5% TL, anterior anal fin ray below dorsal fin ray nos. 15-21, and 5 lateral, subdermal spots of pigmentation (Ref. 34506).
Body shape (shape guide): eel-like.
Four "Discovery" specimens were taken in closing nets between 1510 and 3910 m depth, three of these 1500-2000 m, and one 23 m above the bottom. The "Vityaz" specimen was taken between 3000 m and the surface (Ref. 34506).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Bertelsen, E. and J.G. Nielsen, 1987. The deep sea eel family Monognathidae (Pisces, Anguilliformes). Steenstrupia 13(4):141-198. (Ref. 34506)
IUCN Red List Status (Ref. 130435: Version 2025-2)
Threat to humans
Harmless
Human uses
Fisheries: of no interest
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