Gigantactis

Gigantactis was first proposed as a monospecific genus in 1902 by the German zoologist August Brauer when he described Gigantactis vanhoeffeni.^[3] The type locality of G. vanhoeffeni was given as the Indian Ocean east of Zanzibar from Valdivia station 239 from the surface to a depth of 2,500 m (8,200 ft).^[4] This genus was classified in the monotypic family Gigantactinidae in 1904 by the Belgian-born British ichthyologist George Albert Boulenger,^[5] with a second genus, Rhynchactis, being added by the English ichthyologist Charles Tate Regan in 1925.^[6] The fifth edition of Fishes of the World classifies the whipnose anglers within the suborder Certioidei within the order Lophiiformes, the anglerfishes.^[7]

Giganactis is a combination of gigantos, meaning "giant", with actis, which means "ray", an allusion to the unusually long illicium of genus's type species, G. vanhoeffeni.^[8]

Giganactis contains 22 recognized extant species:^[9]

• Gigantactis balushkini Kharin, 1984
• Gigantactis cheni H. C. Ho & K. T. Shao, 2019
• Gigantactis elsmani Bertelsen, Pietsch & Lavenberg, 1981 (Elsman's Whipnose)
• Gigantactis gargantua Bertelsen, Pietsch & Lavenberg, 1981 (Gigantic Whipnose)
• Gigantactis gibbsi Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis golovani Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis gracilicauda Regan, 1925
• Gigantactis herwigi Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis ios Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis kreffti Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis longicauda Bertelsen & Pietsch, 2002
• Gigantactis longicirra Waterman, 1939
• Gigantactis macronema Regan, 1925
• Gigantactis meadi Bertelsen, Pietsch & Lavenberg 1981
• Gigantactis microdontis Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis microphthalmus Regan & Trewavas, 1932
• Gigantactis paresca Rickle, 2024^[10]
• Gigantactis paxtoni Bertelsen, Pietsch & Lavenberg, 1981 (Paxton's whipnose)
• Gigantactis perlatus Beebe & Crane, 1947
• Gigantactis savagei Bertelsen, Pietsch & Lavenberg, 1981
• Gigantactis vanhoeffeni A. B. Brauer, 1902 (Cosmopolitan whipnose)
• Gigantactis watermani Bertelsen, Pietsch & Lavenberg, 1981

Gigantactis whipnose anglers are distinguished from the other genus in the family, Rhynchactis, by the absence of pelvic bones and by the possession of between 5 and 9 rays, rarely 4 or 10, in the dorsal fin and the anal fin containing between 5 and 7, rarely 4 or 8, soft rays. In the metamorphosed females, the possession of frontal bones, parietal bones with teeth along their full lengths. The maxilla is reduced to a thread-like remnant, and the dentary has several rows of robust, recurved teeth. They have a single hypohyal and spiny skin. The illicium originates on the tip of the snout, the snout being in front of the mouth, with the esca at its tip bearing a bioluminescent organ. The metamorphosed males have larger eyes than those of Rhynchactis, typically having 12 olfactory lamellae, deep nostrils with a depth greater than 9% of the standard length. They normally have 3 upper denticular teeth and 4 lower denticular teeth, all separate from each other. The skin may be either pigmented or unpigmented and may be naked or covered in spinules.^[6] The largest species in the genus is G. vanhoeffeni with a maximum published total length of 62 cm (24 in).^[9]

Gigantactis has a circumglobal distribution in the Atlantic, Indian and Pacific Oceans.^[9] They are found at depths between the surface^[11] and 5,300 m (17,400 ft).^[12]