Linophryne

Linophryne, the bearded seadevils, is a genus of marine ray-finned fishes belonging to the family Linophrynidae, the leftvents. These deep sea anglerfishes are found in the Atlantic, Indian and Pacific Oceans.

Linophryne Temporal range: Late Miocene to Recent PreꞒ Ꞓ O S D C P T J K Pg N [1][2]
L. arborifera
L. lucifer
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Lophiiformes
Family:	Linophrynidae
Genus:	Linophryne Collett, 1886
Type species
Linophryne lucifer Collett, 1886[3]
Synonyms[3]
Aceratias Brauer, 1902 Allector Heller & Snodgrass, 1903 Anomalophryne Regan & Trewavas 1932 Diabolidium Beebe, 1926 Nannoceratias Regan & Trewavas, 1932 Rhizophryne Bertelsen, 1982 Stephanophryne Bertelsen, 1982

Linophryne in the Museum of Scheveningen

Taxonomy

Linophryne was first proposed as a monospecific genus in 1886 by the Norwegian zoologist Robert Collett when he described L. lucifer as a new species.^[3] Collett gave the type locality of L. lucifer as off Madeira at around 36°N, 20°W.^[4] The 5th edition of Fishes of the World classifies this genus within the family Linophrynidae, which it places within the suborder Ceratioidei, the deep sea anglerfishes, within the order Lophiiformes, the anglerfishes.^[5]

Etymology

Linophryne prefixes linos, which means "net", an allusion Collett did not explain when he proposed the genus, with phryne, meaning "toad". The prefix may be a reference to the sac like mouth hanging off the trunk, which in the holotype contained a lanternfish, like a fisherman's keep net. The second part phryne is commonly used in the names of anglerfish genera. Its use may date as far back as Aristotle and Cicero, who referred to anglerfishes as "fishing-frogs" and "sea-frogs," respectively, possibly because of their resemblance to frogs and toads.^[6]

Characteristics

Linophryne leftvents are sexually dimorphic and the metamorphosed females can be distinguished from the other leftvent genera by a number of characters. These include the possession of a hyoid barbel, well-developed spines on the sphenotic bone and the preoperculum and a single nearly oval bulb on the esca with a short projection in its middle and has no appendages as well as a low number of fin rays in the dorsal and anal fins.^[7] The barbel filaments contain globular, bioluminescent organs.^[8][9] The barbels do not contain bacteria like the esca but complex paracrystalline photogenic granules.^{[clarification needed]} The esca is ectodermal in origin whereas the barbel organs may be derived from the mesoderm.^[10]

The different species are distinguished by characters of the esca and barbel;^{[clarification needed][11]} males of the genus cannot be differentiated in morphology.^[12][13] Both sexes are pigmented after metamorphosis, being black in color. They have no scales and gelatinous skin.^[9] The largest species in the genus is L. lucifer which has a maximum published standard length of 27.5 cm (10.8 in).^[14]

Species

Linophryne contains 22 recognised species, these are divided into 3 subgenera:^[14]

• Subgenus Linophryne Collett, 1886
  • Linophryne algibarbata Waterman, 1939
  • Linophryne arcturi Beebe, 1926
  • Linophryne argyresca Regan & Trewavas, 1932
  • Linophryne bicornis Parr, 1927
  • Linophryne bipennata Bertelsen, 1982
  • Linophryne coronata Parr, 1927
  • Linophryne escaramosa Bertelsen, 1982
  • Linophryne lucifer Collett, 1886
  • Linophryne macrodon Regan, 1925
  • Linophryne maderensis Maul, 1961
  • Linophryne polypogon Regan, 1925
  • Linophryne racemifera Regan & Trewavas, 1932
  • Linophryne sexfilis Bertelsen, 1973
  • Linophryne trewavasae Bertelsen, 1978
• Subgenus Rhizophryne Bertelsen, 1982
  • Linophryne andersoni Gon, 1992
  • Linophryne arborifera Regan, 1925
  • Linophryne brevibarbata Beebe, 1932
  • Linophryne densiramus S. Imai, 1941 (Thickbranch angler)
  • Linophryne parini Bertelsen, 1980
  • Linophryne pennibarbata Bertelsen, 1980
• Subgenus Stephanophryne Bertelsen, 1982
  • Linophryne indica Brauer, 1902 (Headlight angler)
  • Linophryne quinqueramosus Beebe & Crane, 1947

Fossil record

Linophryne is represented in the fossil record by what may be L. indica was found in Late Miocene-aged Puente Formation of Los Angeles, California, along with a fossil of the related Borophryne apogon, during the construction of a metrorail.^[1]

Distribution and habitat

Linophryne is found circumglobally in all three equatorial Oceans,^[14] up to as far north as Iceland and Greenland in the Atlantic Ocean.^[15] They are found at depths between 0 and 2,200 m (0 and 7,218 ft).^[16][17]

Gallery

L. arborifera

L. coronata

L. maderensis

L. pennibarbata

L. sexfilis

L. polypogon