''Compsaraia samueli'' is a species of

apteronotid The ghost knifefishes are a family, Apteronotidae, of ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. They inhabit a wide range of freshwater habitats, but more than half the species in the family ...

electric fish that exhibits pronounced sexual dimorphism in which mature males develop extremely elongated snouts and oral jaws. This phenotype is found in several other apteronotid species and is used in agonistic jaw-locking behaviors between males. A study comparing skull shape and jaw-closing performance in males and females of ''Compsaraia samueli'' suggested that males with elongated faces for use in fights also had lower mechanical advantages, indicating a

trade-off A trade-off (or tradeoff) is a situational decision that involves diminishing or losing one quality, quantity, or property of a set or design in return for gains in other aspects. In simple terms, a tradeoff is where one thing increases, and anot ...

between sexual weaponry and jaw leverage. Named in honor of the senior author’s father,

Samuel Albert Samuel ''Šəmūʾēl'', Tiberian: ''Šămūʾēl''; ar, شموئيل or صموئيل '; el, Σαμουήλ ''Samouḗl''; la, Samūēl is a figure who, in the narratives of the Hebrew Bible, plays a key role in the transition from the bibl ...

, who accompanied his son on an electric-fish collecting trip to

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, and purchased type specimens from a fish market near

Iquitos Iquitos (; ) is the capital city of Peru's Maynas Province and Loreto Region. It is the largest metropolis in the Peruvian Amazon, east of the Andes, as well as the ninth-most populous city of Peru. Iquitos is the largest city in the world tha ...

when he recognized that they differed from all the other electric fishes they had been collecting by the prominent elongate jaws of mature males.

References

Taxa named by James S. Albert Taxa named by William Gareth Richard Crampton Fish described in 2009 Weakly electric fish Apteronotidae {{Gymnotiformes-stub