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Gnathifera (clade)

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Gnathifera
Temporal range:Fortunian–Recent
Pseudosagitta maxima(Chaetognatha)
Brachionus quadridentatus(Rotifera)
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Clade: Bilateria
Clade: Nephrozoa
(unranked): Protostomia
(unranked): Spiralia
Clade: Gnathifera
Ahlrichs, 1995
Phyla

Gnathifera(from theGreekgnáthos,“jaw”, and theLatin-fera,“bearing” ) is a clade of generally smallspiralianscharacterized by complex jaws made ofchitin.It comprises the phylaGnathostomulida,RotiferaandMicrognathozoa.[1]Chaetognathahas recently been recognised as closely related to the group, with it either being included within Gnathifera[1]or the broader groupChaetognathifera.[2]

Gnathiferans include some of the most abundant phyla. Rotifers are among the most diverse and abundant freshwater animals and chaetognaths are among the most abundant marine plankton.[3][4]

Description

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Comparison of the head region of Gnathifera

The most distinctive characteristic of gnathiferans is the presence of complex sclerotized mouthparts made of chitin.[1]

In most gnathiferans, the anus opens on the dorsal surface of the animal.[5][6][7]In micrognathozoans and gnathostomulids, the anus is transient and only forms during defecation.[6][7]Unlike other gnathiferans, in chaetognaths and the extinctAmiskwiathe anus is located on the ventral surface in a subterminal position.[8][9]

Both Gnathostomulida and Micrognathozoa areacoelomates,rotifers arepseudocoelomates,and chaetognathans have a truecoelom.Gnathostomulidans and chaetognathans arehermaphrodites,and Micrognathozoa appears to beparthenogeneticas no males have ever been observed, but it has been suggested undiscovered dwarf males could be responsible for fertilization. In rotifers both males and females occurs, except from the classBdelloidea.[10][11][12][13][14][15][16]

Development

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All known gnathiferans aredirect developers.[17]Though gnathiferans are included in Spiralia, rotifers and chaetognaths do not exhibit spiralcleavage.[17][1]Little is known of the development of micrognathozoans.[17]The development of gnathostomulids is poorly known, but they appear to exhibit spiral cleavage.[17][1]

Classification

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Spiralia
Summary of relationships of gnathiferans in recent studies, with disputed relationships represented as polytomies[1][5][18][19][20]

Gnathifera is a member of Spiralia. It is the sister taxon of a clade comprising all other spiralians.[1][19]Before the cladistic era, most gnathiferans were regarded asaschelminths,a grouping now recognized aspolyphyletic.

Chaetognaths exhibit numerous morphological similarities to rotifers, suggesting that they may be sister taxa.[5][18]However, based on molecular data, micrognathozoans may be more closely related to rotifers than chaetognaths.[1]

Rotifera comprises four subclades:Seisonida,Acanthocephala,Bdelloidea,andMonogononta.Acanthocephalans were traditionally excluded from Rotifera, but it is now known that rotifers are paraphyletic without including acanthocephalans. Some taxonomists call the clade of rotifers including acanthocephalans Syndermata, but others continue to use Rotifera and regard acanthocephalans as rotifers.[19]Numerous hypotheses of rotifer interrelationships exist.[19][20]

The Enigma tic phylumCycliophoramay belong to Gnathifera, but other studies suggest that it is more closely related to theEntoprocta.[21]

Fossil record

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Amiskwia sagittiformisa basal gnathiferan from Cambrian of Canada, which is much larger than modern gnathiferans

The fossil record of gnathiferans is poor. There are no known fossil gnathostomulids.[22]Fossils of the extant rotifer genusHabrotrochaare known fromDominican amberdating to the lateEocene,but rotifers are otherwise only known from theHolocene.[23][24]By contrast, the chaetognath fossil record, while still patchy, includes numerousPaleozoicspecimens.[25]Protoconodontsare stem-group chaetognaths.[26]The earliest protoconodonts date to theFortunianage of theCambrian,and are among the oldest known bilaterians.[27]The Enigma tic Cambrian taxonAmiskwiais a gnathiferan and may also be a stem-group chaetognath.[5][8]The Cambrian ectoparasiteInquicusappears to be a gnathiferan.[5]

History

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Gnathifera was named in 1995 to unite gnathostomulids and rotifers. Micrognathozoans were soon added to this grouping. Chaetognaths, long considered a distinct lineage with no close relatives, were identified as gnathiferans in 2019.[1]

A similar grouping, Acanthognatha, was suggested in 1998 to unitegastrotrichswith gnathostomulids and rotifers.[28]However, gastrotrichs are more closely related to lophotrochozoans than gnathiferans.[19][1]

References

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  1. ^abcdefghijMarlétaz, Ferdinand; Peijnenburg, Katja T. C. A.; Goto, Taichiro; Satoh, Noriyuki; Rokhsar, Daniel S. (2019)."A new spiralian phylogeny places the Enigma tic arrow worms among gnathiferans".Current Biology.29(2): 312–318.e3.Bibcode:2019CBio...29E.312M.doi:10.1016/j.cub.2018.11.042.PMID30639106.
  2. ^Park, Tae-Yoon S.; Nielsen, Morten Lunde; Parry, Luke A.; Sørensen, Martin Vinther; Lee, Mirinae; Kihm, Ji-Hoon; Ahn, Inhye; Park, Changkun; de Vivo, Giacinto; Smith, M. Paul; Harper, David A. T.; Nielsen, Arne T.; Vinther, Jakob (2024-01-05)."A giant stem-group chaetognath".Science Advances.10(1): eadi6678.Bibcode:2024SciA...10I6678P.doi:10.1126/sciadv.adi6678.ISSN2375-2548.PMC10796117.PMID38170772.
  3. ^Suga K, Mark Welch D, Tanaka Y, Sakakura Y, Hagiwara A (2007)."Analysis of expressed sequence tags of the cyclically parthenogenetic rotifer Brachionus plicatilis".PLOS ONE.2(7): e671.Bibcode:2007PLoSO...2..671S.doi:10.1371/journal.pone.0000671.PMC1925144.PMID17668053.
  4. ^Longhurst, Alan R. (1985). "The structure and evolution of plankton communities".Progress in Oceanography.15(1): 1–35.Bibcode:1985PrOce..15....1L.doi:10.1016/0079-6611(85)90036-9.
  5. ^abcdeVinther, Jakob; Parry, Luke A. (2019)."Bilateral jaw elements in Amiskwia sagittiformis bridge the morphological gap between gnathiferans and chaetognaths".Current Biology.29(5): 881–888.e1.Bibcode:2019CBio...29E.881V.doi:10.1016/j.cub.2019.01.052.hdl:1983/51b1b6c1-0220-4469-977f-480e847a9101.PMID30799238.
  6. ^abKnauss, Elizabeth B. (1979). "Indication of an anal pore in Gnathostomulida".Zoologica Scripta.8(1–4): 181–186.doi:10.1111/j.1463-6409.1979.tb00630.x.S2CID84391082.
  7. ^abKristensen, Reinhardt Møbjerg; Funch, Peter (2000). "Micrognathozoa: a new class with complicated jaws like those of Rotifera and Gnathostomulida".Journal of Morphology.246(1): 1–49.doi:10.1002/1097-4687(200010)246:1<1::AID-JMOR1>3.0.CO;2-D.PMID11015715.S2CID13294045.
  8. ^abCaron, Jean-Bernard; Cheung, Brittany (2019)."Amiskwia is a large Cambrian gnathiferan with complex gnathostomulid-like jaws".Communications Biology.2:164.doi:10.1038/s42003-019-0388-4.PMC6499802.PMID31069273.
  9. ^Arnaud, Jean; Brunet, Michel; Casanova, Jean-Paul; Mazza, Jacques; Pasqualini, Vanina (1996). "Morphology and ultrastructure of the gut in Spadella cephaloptera (Chaetognatha)".Journal of Morphology.228(1): 27–44.doi:10.1002/(SICI)1097-4687(199604)228:1<27::AID-JMOR3>3.0.CO;2-M.PMID29852579.S2CID46918465.
  10. ^The Gnathifera
  11. ^Rotifers as live feed
  12. ^Struck, Torsten H.; Wey-Fabrizius, Alexandra R.; Golombek, Anja; Hering, Lars; Weigert, Anne; Bleidorn, Christoph; Klebow, Sabrina; Iakovenko, Nataliia; Hausdorf, Bernhard; Petersen, Malte; Kück, Patrick; Herlyn, Holger; Hankeln, Thomas (July 2014)."Platyzoan Paraphyly Based on Phylogenomic Data Supports a Noncoelomate Ancestry of Spiralia".Molecular Biology and Evolution.31(7): 1833–1849.doi:10.1093/molbev/msu143.PMID24748651.
  13. ^Phylum Chaetognatha - Australian Faunal Directory
  14. ^Morphology of the nervous system of monogonont rotifer Epiphanes senta with a focus on sexual dimorphism between feeding females and dwarf males
  15. ^Yin, Xu-Wang; Tan, Bing-Bing; Zhou, Yan-Chun; Li, Xiao-Chun; Liu, Wei (2016)."Development time of male and female rotifers with sexual size dimorphism".Hydrobiologia.767(1): 27–35.doi:10.1007/s10750-015-2472-1.
  16. ^Birky, C. William (2004)."Bdelloid rotifers revisited".Proceedings of the National Academy of Sciences of the United States of America.101(9): 2651–2652.Bibcode:2004PNAS..101.2651B.doi:10.1073/pnas.0308453101.ISSN0027-8424.PMC365675.PMID14981265.
  17. ^abcdHejnol, Andreas (2015). "Gnathifera". In Wanninger, A. (ed.).Evolutionary Developmental Biology of Invertebrates 2: Lophotrochozoa (Spiralia).Springer. pp. 1–12.doi:10.1007/978-3-7091-1871-9_1.ISBN978-3-7091-1870-2.
  18. ^abFröbius, Andreas C.; Funch, Peter (2017)."Rotiferan Hox genes give new insights into the evolution of metazoan bodyplans".Nature Communications.8(1): 9.Bibcode:2017NatCo...8....9F.doi:10.1038/s41467-017-00020-w.PMC5431905.PMID28377584.
  19. ^abcdeLaumer, Christopher E.; Bekkouche, Nicolas; Kerbl, Alexandra; Goetz, Freya; Neves, Ricardo C.; Sørensen, Martin V.; Kristensen, Reinhardt M.; Hejnol, Andreas; Dunn, Casey W.; Giribet, Gonzalo; Worsaae, Katrine (2015)."Spiralian phylogeny informs the evolution of microscopic lineages".Current Biology.25(15): 2000–2006.Bibcode:2015CBio...25.2000L.doi:10.1016/j.cub.2015.06.068.PMID26212884.
  20. ^abSielaff, Malte; Schmidt, Hanno; Struck, Torsten H.; Rosenkranz, David; Mark Welch, David B.; Hankeln, Thomas; Herlyn, Holger (2016). "Phylogeny of Syndermata (syn. Rotifera): Mitochondrial gene order verifies epizoic Seisonidea as sister to endoparasitic Acanthocephala within monophyletic Hemirotifera".Molecular Phylogenetics and Evolution.96:79–92.Bibcode:2016MolPE..96...79S.doi:10.1016/j.ympev.2015.11.017.PMID26702959.
  21. ^Kristensen, Reinhardt Møbjerg (2002)."An Introduction to Loricifera, Cycliophora, and Micrognathozoa".Integrative and Comparative Biology.42(3): 641–651.doi:10.1093/icb/42.3.641.PMID21708760.
  22. ^Piper, Ross (2013).Animal Earth: The Amazing Diversity of Living Creatures.Thames & Hudson.
  23. ^Poinar, G. O.; Ricci, C. (1992). "Bdelloid rotifers in Dominican amber: evidence for parthenogenetic continuity".Experientia.48(4): 408–410.doi:10.1007/bf01923444.S2CID13098228.
  24. ^Waggoner, B. M.; Poinar, G. O. (1993). "Fossil habrotrochid rotifers in Dominican amber".Experientia.49(4): 354–357.doi:10.1007/bf01923421.S2CID28087284.
  25. ^Vannier, J.; Steiner, M.; Renvoisé, E.; Hu, S.-X.; Casanova, J.-P. (2007)."Early Cambrian origin of modern food webs: evidence from predator arrow worms".Proceedings of the Royal Society B.274(1610): 627–633.doi:10.1098/rspb.2006.3761.PMC2197202.PMID17254986.
  26. ^Szaniawski, Hubert (2002)."New evidence for the protoconodont origin of chaetognaths".Acta Palaeontologica Polonica.47(3): 405–419.
  27. ^Kouchinsky, Artem; Bengtson, Stefan; Runnegar, Bruce; Skovsted, Christian; Steiner, Michael; Vendrasco, Michael (2011)."Chronology of early Cambrian biomineralization".Geological Magazine.149(2): 221–251.doi:10.1017/S0016756811000720.
  28. ^Cavalier-Smith, T. (1998). "A revised six-kingdom system of life".Biological Reviews.73(3): 203–266.doi:10.1111/j.1469-185X.1998.tb00030.x.PMID9809012.S2CID6557779.
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