Oneirodes

Oneirodes is a genus of predatory, deep-sea anglerfish found in oceans worldwide. It belongs to the family Oneirodidae, commonly known as dreamers, and serves as both the type genus and the most species-rich genus within that family. The fish exhibit sexual dimorphism, but unlike some other anglerfish groups, the small males are free-living and do not attach themselves as parasites to the larger females. Because no species-specific physical traits have been identified in males, only females are used to distinguish between species.

The genus was first established in 1871 by Danish zoologist Christian Frederik Lütken, who described a single species, Oneirodes eschrichtii, from waters off western Greenland. In 1878, Theodore Gill created the family Oneirodidae with O. eschrichtii as its only member, making Oneirodes the family’s type genus. The genus is classified within the suborder Ceratioidei of the anglerfish order Lophiiformes.

The name Oneirodes means “dream-like.” Lütken never explained why he chose it. In 1898, David Starr Jordan and Barton Warren Evermann suggested it referred to the fish’s small, skin-covered eyes. In 2009, Theodore Wells Pietsch III proposed that the name reflected the fish’s strange and marvelous appearance, something that could only be imagined in the dark of night during unconsciousness.

Oneirodes contains more species than any other genus in its family.

Lore & Background

Oneirodes was first proposed as a monospecific genus in 1871 by the Danish zoologist Christian Frederik Lütken when he described Oneirodes eschrichtii, with the type locality off the western coast of Greenland. Theodore Gill named the family Oneirodidae in 1878 with O. eschrichtii as its only species, making Oneirodes the type genus of its family. The 5th edition of Fishes of the World classifies this genus in the family Oneirodidae in the suborder Ceratioidei of the anglerfish order Lophiiformes.

The etymology of Oneirodes means "dream-like." Lütken did not explain this choice of name. David Starr Jordan and Barton Warren Evermann suggested in 1898 that the name referred to the small, skin-covered eyes. Alternatively, in 2009, Theodore Wells Pietsch III proposed that the name was given because the fish is "so strange and marvelous that it could only be imagined in the dark of the night during a state of unconsciousness."

Oneirodes dreamers are characterised by having spines on the sphenotic bone, a deep incision on the rear edge of the operculum, and rod-shaped pelvic bones that are not expanded or expanded only slightly at the tips. The illicium emerges from between the frontal bones, and a unique character of the metamorphosed females is that the posterior end of the pterygiophore of the illicium emerges from the skin on the back, behind the head. The males have unpigmented skin between the nostrils, and the inner surface of the subopercle is also unpigmented. The males are free-living and non-parasitic.

Scientific classification

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Lore & Background

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