Beardfish Explained

The beardfishes consist of a single extant genus, Polymixia, of deep-sea marine ray-finned fish named for their pair of long hyoid barbels. They are classified in their own order Polymixiiformes . But as Nelson says, "few groups have been shifted back and forth as frequently as this one, and they were recently added to Paracanthoptergii".^[1] For instance, they have previously been classified as belonging to the Beryciformes, and are presently considered either paracanthopterygians or the sister group to acanthopterygians. They are of little economic importance.^[2]

They are found in tropical and subtropical waters of the Atlantic, Indian and western Pacific Ocean. They are bottom-dwelling fish, found down to about 800m (2,600feet) depth. Most are relatively small fish, although one species, Polymixia berndti, is over 40cm (20inches) in length.^[2]

The earliest body fossils are from the Late Cenomanian of Lebanon, of the genus Pycnosteroides.^[3] However, tentative earlier records are known from distinctive fossil otoliths from the Early Cretaceous (Albian) of Texas, USA.^[4] Many different fossil families and genera are known from the Late Cretaceous and early Cenozoic, in contrast to the relatively few surviving species in a single genus.^[5] Extant beardfish can thus be considered "living fossils".^[6]

Classification

• Order Polymixiiformes Rosen & Patterson, 1969^{[7] [8]}
  • Genus ?†Allocyclostoma Schwarzhans, Stringer & Welton, 2022 [<nowiki/>[[otolith]]]
    • †A. alienus Schwarzhans, Stringer & Welton, 2022
  • Genus †Cumbaaichthys Murray 2016
    • †Cumbaaichthys oxyrhynchus Murray 2016
  • Genus †Severnichthys Stringer & Schwarzhans, 2021 [<nowiki/>otolith]^[9]
    • †S. beauryi (Schwarzhans, 2010)
    • †S. bourdoni Stringer & Schwarzhans, 2021
  • Genus ?†Texoma Schwarzhans, Stringer & Welton, 2022 [otolith]
    • †T. cyclogaster Schwarzhans, Stringer & Welton, 2022
  • Family †Boreiohydriidae Murray & Cumbaa 2013
    • Genus †Boreiohydrias Murray & Cumbaa 2013
      • †Boreiohydrias dayi Murray & Cumbaa 2013
  • Family †Dalmatichthyidae Radovčić 1975
    • Genus †Dalmatichthys Radovčić 1975
      • †Dalmatichthys malezi Radovčić 1975
  • Family †Digoriidae Bannikov 1985
    • Genus †Digoria Daniltshenko, 1980
      • †Digoria ambigua Daniltshenko, 1980
  • Family †Dinopterygidae Jordan, 1923
    • Genus †Dinopteryx Woodward, 1901
      • †Dinopteryx spinosus (Davis, 1887)
  • Family Polymixiidae Gill 1862 [Berycopsidae <small>Regan 1911</small>; Dalmatichthyidae <small>Radovčić 1975</small>; Omosomopsidae <small>Gaudant 1978</small>; Homonotichthyidae <small>Whitley 1933</small>]
    • Genus †Apricenaichthys Taverne 2011
      • †Apricenaichthys italicus
    • Genus †Berycopsia Radovčić 1975
      • †Berycopsia inopinnata Radovčić 1975
    • Genus †Berycopsis Dixon 1850 [''[[Platycormus]] von der Marck 1900]
      • †B. elegans Dixon 1850 [''Platycormus elegans'' <small>(Dixon 1850)</small>]
      • †B. germana (Agassiz 1839) [''Beryx germanus'' <small>Agassiz 1839</small>; ''Platycormus germanus'' <small>(Agassiz 1839)</small>]
      • †B. pulcher Bannikov & Bacchia 2004
    • Genus †Cowetaichthys Schwarzhans, Huddleston & Takeuchi, 2018 [otolith]^[10]
      • †C. alabamae Schwarzhans, Huddleston & Takeuchi, 2018
      • †C. beauryi (Schwarzhans, 2010)
      • †C. carnevalei Schwarzhans & Stringer, 2020
      • †C. groenlandicus (Schwarzhans, 2004)
      • †C. harderi (Schwarzhans, 2003)
      • †C. lamberi Schwarzhans, Huddleston & Takeuchi, 2018
    • Genus †Homonotichthys Whitley 1933
      • †H. dorsalis (Dixon 1850) [''Homonotus dorsalis'' <small>Dixon 1850</small>]
      • †H. elegans (Dixon 1850) [''Homonotus elegans'' <small>Dixon 1850</small>]
      • †H. rotundus (Woodward 1902) [''Homonotus rotundus'' <small>Woodward 1902</small>]
    • Genus †Namicauda Schwarzhans, Ohe & Ando, 2017 [otolith]^[11]
      • †Namicauda pulvinata Schwarzhans, Ohe & Ando, 2017
    • Genus †Omosoma Costa 1857
      • †O. garretti Bardack 1976
      • †O. pulchellum Davis 1887
      • †O. sahelalmae Costa 1857
      • †O. tselfatense Gaudant 1978
    • Genus †Omosomopsis Gaudant 1978
      • †Omosomopsis sima (Arambourg 1954) Gaudant 1978
    • Genus †Parapolymixia David 1946
      • †Parapolymixia californica David 1946
    • Genus †Pycnosterinx Heckel 1849 [''[[Imogaster]] Costa 1857]
      • †P. discoides Heckel 1849
      • †P. dorsalis Pictet 1850
      • †P. heckelii Pictet 1850
      • †P. latus Davis 1887
      • †P. russeggeri Heckel 1849 [''Homonotus pulcher'' <small>Davis 1886</small>]
    • Genus Polymixia Lowe 1836 [''[[Dinemus]] Poey 1860; Nemobrama Valenciennes 1860 non Jordan, Evermann & Clark 1930]
      • P. berndti Gilbert 1905 (Pacific beardfish)
      • P. busakhini Kotlyar 1993 (Busakhin's beardfish)
      • P. carmenae Caixeta, Oliveira & de Melo, 2024 (Brazilian beardfish)^[6]
      • P. fusca Kotthaus 1970
      • †?P. harderi (Schwarzhans 2003) [otolith]^[12]
      • P. hollisterae Grande & Wilson, 2021 (Bermuda beardfish)
      • P. japonica Günther 1877 (Silver eye)
      • P. longispina Deng, Xiong & Zhan 1983 [''Polymixia kawadae'' <small>Okamura & Ema 1985</small>]
      • P. lowei Günther 1859 (Beardfish)
      • P. nobilis Lowe 1838 [''Nemobrama webbii'' <small>Valenciennes 1837</small>; ''Dinemus venustus'' <small>Poey 1860</small>; ''Polymixia nobilis virginica'' <small>Nichols & Firth 1936</small>] (Stout beardfish)
      • †P. polita Schwarzhans 2012 [otolith]
      • P. salagomeziensis Kotlyar 1991
      • P. sazonovi Kotlyar 1992
      • P. yuri Kotlyar 1982
    • Genus †Polyspinatus Schrøder, Rasmussen, Møller & Carnevale, 2022
      • †Polyspinatus fluere Schrøder, Rasmussen, Møller & Carnevale, 2022
  • Family †Pycnosteroididae Patterson, 1964
    • Genus †Magrebichthys Murray & Wilson 2014
      • †Magrebichthys nelsoni Murray & Wilson 2014
    • Genus †Pycnosteroides Woodward, 1942
      • †Pycnosteroides levispinosus (Hay, 1903)

References

• Sepkoski . Jack . A compendium of fossil marine animal genera . Bulletins of American Paleontology . 364 . 560 . 2002 . 2011-05-17 . https://web.archive.org/web/20110723131237/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class . 2011-07-23 .

Notes and References

1. Book: Joseph S. Nelson . . 29 April 1994 . John Wiley & Sons . 0-471-54713-1.
2. Book: Paxton, J.R. . Eschmeyer, W.N. . Paxton, John R.. 1998. Encyclopedia of Fishes. Academic Press. San Diego. 161. 0-12-547665-5.
3. Schrøder . Ane Elise . Rasmussen . Jan Audun . Møller . Peter Rask . Carnevale . Giorgio . 2022-08-31 . A new beardfish (Teleostei, Polymixiiformes) from the Eocene Fur Formation, Denmark . Journal of Vertebrate Paleontology . en . 42 . 2 . 10.1080/02724634.2022.2142914 . 0272-4634. 10037/28645 . free .
4. Schwarzhans . Werner . Stringer . Gary L. . Welton . Bruce . 2022-12-01 . Oldest Teleostean Otolith Assemblage from North America (Pawpaw Formation, Lower Cretaceous, upper Albian, northeast Texas, USA) . Cretaceous Research . 140 . 105307 . 10.1016/j.cretres.2022.105307 . 0195-6671. free .
5. Murray . Alison M. . 2014 . Mid-Cretaceous acanthomorph fishes with the description of a new species from the Turonian of Lac des Bois, Northwest Territories, Canada . Vertebrate Anatomy Morphology Palaeontology . en . 1 . 101–115 . 10.18435/B5CC78 . 2292-1389. free .
6. De Cia Caixeta . Heloísa . Oliveira . Claudio . Melo . Marcelo Roberto Souto de . 2024-03-01 . Another piece of the living fossil puzzle: A new species of Polymixia Lowe, 1836 (Polymixiiformes: Polymixiidae) from the western South Atlantic . Deep Sea Research Part I: Oceanographic Research Papers . 205 . 104249 . 10.1016/j.dsr.2024.104249 . 0967-0637.
7. Web site: Mikko's Phylogeny Archive. Haaramo. Mikko. 2007. Polymixiomorpha – beardfishes and relatives . 30 December 2016.
8. Collection of genus-group names in a systematic arrangement. Part 7- Vertebrates. etal. 30 June 2016. https://web.archive.org/web/20161005114629/http://mave.tweakdsl.nl/tn/genera7.html. 2016-10-05.
9. Stringer . Gary . Schwarzhans . Werner . 2021 . Upper Cretaceous teleostean otoliths from the Severn Formation (Maastrichtian) of Maryland, USA, with an unusual occurrence of Siluriformes and Beryciformes and the oldest Atlantic coast Gadiformes . Cretaceous Research . 125 . 104867 . 10.1016/j.cretres.2021.104867 . 0195-6671. free .
10. SCHWARZHANS . WERNER W. . HUDDLESTON . RICHARD W. . TAKEUCHI . GARY T. . 2018-01-22 . A LATE SANTONIAN FISH-FAUNA FROM THE EUTAW FORMATION OF ALABAMA RECONSTRUCTED FROM OTOLITHS . Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy) . en . V. 124 . N. 1 (2018) . 10.13130/2039-4942/9624.
11. Schwarzhans . Werner . Ohe . Fumio . Ando . Yusuke . 2017 . An Early Oligocene fish-fauna from Japan reconstructed from otoliths . Zitteliana . 3–26 . 10.5282/ubm/epub.40475 . 0373-9627.
12. Web site: 2017-02-15 . Bulletin Volume 65 – 2017 . 2024-07-28 . Dansk Geologisk Forening . da-DK . 10.37570/bgsd-2017-65-05.